Elevating Berry Excellence: GABA-Induced Stimulation of Anthocyanin Biosynthesis and Antioxidant Defense in Flame Seedless Grapes

Elevating Berry Excellence: GABA-Induced Stimulation of Anthocyanin Biosynthesis and Antioxidant Defense in Flame Seedless Grapes | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Elevating Berry Excellence: GABA-Induced Stimulation of Anthocyanin Biosynthesis and Antioxidant Defense in Flame Seedless Grapes Khushi Kumari, Rachna Arora, Naresh Kumar Arora, Shalini Jhanji, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9036075/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 9 You are reading this latest preprint version Abstract The grapevine ( Vitis vinifera L.) stands as one of the most important fruit crops due to its high nutritional value, palatability and economic significance. In order to mitigate the harmful effects of climate change on fruit quality, primarily the berry colouration and antioxidant potential, the present study was conducted to investigate the potential of foliar application of γ-aminobutyric acid (GABA) during two consecutive cropping seasons on grape cv. Flame Seedless. At the onset of veraison, 17-year-old vines were sprayed with GABA @ 25, 50 and 100 mM. The results revealed that GABA @100 mM significantly improved total phenolic content and antioxidants, remaining statistically comparable with GABA @50 mM. Fruit colour was also favourably influenced, as it produced higher a* and lower b* values, improving berry appearance. Moreover, it also improved the cluster and berry physical traits by recording the highest cluster length, width and weight, along with increased berry size, berry weight and yield. Antioxidant enzymes, including catalase (CAT), phenylalanine ammonia-lyase (PAL) and superoxide dismutase (SOD), were significantly elevated under all treatments, with 50 and 100 mM concentrations exhibiting the strongest responses. GABA @50 mM recorded the highest TSS, lowest L* values and maximum total anthocyanin content, followed closely by 100 mM. Overall, pre-harvest foliar GABA @ 50–100 mM offers great potential to enhance grape productivity, quality, adaptability, precision nutrient use, deficit irrigation efficiency, eco-friendly cultivation and premium export. anthocyanins antioxidants phenolics fruit colour Flame Seedless Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction The grapevine ( Vitis vinifera L.) belongs to the family Vitaceae which consists of 12 genera and 600 species. Due to its extensive global cultivation, it is regarded as one of the most economically significant fruit crops. Besides carbohydrates (17 g/100 g), grapes also have a high caloric content (65 kcal/100 g) and a relatively low glycemic index. Apart from being a superb provider of K and Mn, they also contain a considerable amount of vitamin B1, B6 and C (Unusan N 2020 ). It has a variety of bioactive substances, the amounts of which can vary greatly in grape skin, pulp and seed. These include proanthocyanidins, anthocyanins, flavonols, phenolic acids and stilbenes. Numerous studies have demonstrated many health benefits associated with grapes, including their anti-inflammatory, anti-tumor, gut-microbiota-modulating, antioxidant and cardioprotective properties (Zhou et al. 2022 ). The commercial value of grapes cv. Flame Seedless, created by J. Weinberger and F. Harmon in 1989 is determined by their form, cluster size, quality and attractiveness (Abdel-Sattar et al. 2022 ). Although this is superior to many other variants in terms of its crimson red color, seedless berries, high TSS:Acid, medium bunch size and extended shelf life, the major obstacle to grow it is uneven berry pigmentation which is best facilitated by summer's high temperatures and sugar content resulting in diminished anthocyanins synthesis (Akram et al. 2020 ). Since uniform, bright red berries are associated with ripeness, sweetness and superior quality, uneven colour often creates a perception of inferior fruit even when internal quality is acceptable. For farmers, this directly translates into increased sorting and labour costs, postharvest losses and rejection in premium export markets. Since there is little ability to regulate the climate in open fields, alternative methods of regulating colour development and antioxidant capacity must be investigated. In recent years various plant growth stimulants have been used to improve grape colour, chemical contents and other quality parameters. First discovered in potato tubers, a water soluble, non-protein amino acid with four carbon atoms and an amino group on the γ-carbon, GABA may be used as an effective technique to enhance the quality of horticultural crops due to its capacity to develop stress tolerance (Li et al. 2021 ;Kawade et al. 2023 ). It builds up as a result of plant reactions to environmental stressors, increasing the plant stress tolerance through enhanced photosynthesis, triggering antioxidant enzymes and controlling stomatal opening during drought stress (Li et al. 2021 ). It has been extensively investigated in animal central nervous systems where it functions as an inhibitory neurotransmitter while in plants, it is broken down via the GABA shunt pathway, a bypass of the TCA cycle, in which the glutamate decarboxylase enzyme converts glutamate into GABA. It functions as a signal in Agrobacterium tumefaciens -mediated plant gene transformation and in plant development (root growth, fruit ripening, seed germination and pollen tube elongation) as well as regulates a number of physiological processes, including senescence, cytosolic pH, redox status and osmotic moiety. At the molecular level, the cytosolic GABA shunt functions as a signaling molecule, scavenging ROS and shielding the plant from oxidative harm (Badiche et al. 2023 ). More recently, a variety of fruit species, including table grape, cornelian, mango and kiwifruit have been shown to be benefitted from postharvest GABA treatments in terms of preserving quality attributes (Asgarian et al. 2022 ; Aghdam et al. 2019 ; Rastegar et al. 2020 ; Liu et al. 2023 ). As GABA increases antioxidant enzymes, it has been demonstrated to be a successful method for maintaining postharvest quality and improving the storage performance of bananas, citrus, cucumber and peaches (Wang et al. 2014 ; Sheng et al. 2017 ; Malekzadeh et al. 2017 ; Aghdam et al. 2015 ; Shang et al. 2011 ; Yang et al 2011 ). Exogenously administered GABA can raise endogenous GABA levels, which has positive effects on plant growth and development similar to intrinsically formed molecule (Ramos-Ruiz et al. 2019 ). Without changing fruit hardness, total soluble solids or titratable acidity, GABA treatment in lemon cv. Fino-95 enhanced crop yield (Badiche et al. 2023 ). Moreover, applying a GABA foliar spray to apple trees one or two weeks prior to harvest reduced the symptoms of soft scald following cold storage (Al-Shoffe et al. 2021). Based on prior research, the primary objective of the current investigation was to test the hypothesis that preharvest GABA treatments could improve table grape cv . Flame Seedless quality characteristics, particularly anthocyanin accumulation and antioxidant potential at harvest. Material and Methods Plant material and treatments During two consecutive cropping seasons (2023–2024 and 2024–2025), the present investigation was conducted on 17-years-old own-rooted vines of table grape ( Vitis vinifera L.) cv. Flame Seedless at the Fruit Research Farm, Department of Fruit Science, Punjab Agricultural University (PAU), Ludhiana, Punjab, India. The soil contained 121g clay, 146g silt and 721g sand/kg with a pH of 8.1 and was salinity-free (0.30 dS/m). It possessed medium organic carbon (4.3 g OC/kg), 25.8 mg extractable P/kg and 319.5 mg NH4OAc-extractable K/kg. The vines were grown in sandy soil under a drip irrigation system and trained on a bower system at a spacing of 3 × 3 m. A total of 16 uniform vines were selected randomly and divided into four treatments, each comprising of four vines. At the onset of veraison, a crucial turning point characterised by significant changes to the cell wall, a sharp rise in sugar content, a decrease in acidity and a change in skin coloration (accumulation of anthocyanins and a change from green to red), bunches from the first three treatments were sprayed with GABA @ 25 mM (T1), 50 mM (T2) and 100 mM (T3), each prepared with 0.1% (v/v) Tween 80 as a surfactant. The fourth treatment (T4) served as the control. Each vine represented one replication, resulting in four replications per treatment. Grape samples were harvested at the commercial maturity stage and immediately transported to the Postgraduate Laboratory, PAU, Ludhiana. For physico-chemical evaluation, a total sample of 4 kg per treatment (1 kg per vine) was collected, cleaned off the dirt immediately and analysed for various parameters following standard procedures, as described below. Fruit yield and physical attributes Overall yield (kg/vine) was estimated by multiplying the average cluster weight per vine with the total number of clusters per vine. Cluster length and width (cm) were measured using a measuring scale, while cluster weight (g) and berry weight (g) were recorded using an electronic balance. Berry diameter and length (mm) were measured with a vernier calliper. Fruit colour was measured colorimetrically on two opposite equatorial sides of thirty berries per treatment using a Minolta colorimeter (Minolta Co. Ltd., Osaka, Japan). The brightness of the fruit surface is represented by the L* (lightness) values, which range from 0 (black) to 100 (white). On the other hand, positive values for a* correspond to red and negative values to green. Similarly positive values for b* indicate yellow and negative values for blue. Biochemical attributes TSS was measured at room temperature using a Bausch and Lomb hand refractometer and expressed as °Brix, with values corrected to 20 °C using a temperature correction table. Total phenolic content was determined by Folin–Ciocalteu reagent (FCR) method using a gallic acid standard curve and expressed as mg gallic acid equivalents (GAE)/100 g FW as described by Malik and Singh (1980). Briefly, 1 mL of fruit methanolic extract was evaporated at 70–75°C, mixed with 6.5 mL of deionized water and 0.5 mL of FCR, and after 5 min, 1 mL of saturated sodium carbonate solution (35 g/100 mL water) was added. The mixture was incubated in the dark for 1 h for development of a dark blue colour and absorbance was recorded at 760 nm against a blank of FCR diluted with distilled water (1:1). Total anthocyanin content was determined following the method of Fuleki and Francis (1968), in which 5 g of crushed fruit peel was extracted with 100 mL of reagent A (95% ethanol and 0.1 N HCl, 85:15) and stored overnight at 4°C. After 4–5 filtrations, the volume was adjusted to 100 mL with reagent A, and a 10 mL aliquot was kept in the dark for 24 h. For estimation, 10 mL of reagent A was added to the aliquot, and absorbance was recorded at 535 nm against a reagent A blank. Total anthocyanin content (mg/g FW) was calculated using the formula: Antioxidative defense enzyme activities Antioxidant activity was assessed using the DPPH radical scavenging assay described by Blois (1958). A reaction mixture containing 0.1 mL of methanolic fruit extract and 0.29 mL of 0.1 mM DPPH solution was incubated in the dark for 30 min and absorbance was recorded at 517 nm using a control. Radical scavenging activity (%) was calculated as , where and represent the absorbance of the control and sample, respectively. For CAT, enzyme was extracted by homogenizing 0.1 g fruit tissue in 2 mL of cold sodium phosphate buffer (pH 7.5), followed by centrifugation at 10,000 rpm for 30 min at 4°C. The enzymatic activity was measured according to Rukunuzzaman et al. (2025) by adding 1 mL H₂O₂ solution (diluting 0.2 mL of 30% H₂O₂ to 50 mL with 50 mM sodium phosphate buffer, pH 7.5) to a reaction mixture containing 1.8 mL buffer and 0.2 mL enzyme extract, and monitoring the optical density at 240 nm every 30 s for 3 min. SOD activity was assayed following Marklund and Marklund (1974) based on inhibition of pyrogallol auto-oxidation, where the reaction mixture contained 1.5 mL Tris-HCl buffer (0.1 M, pH 8.2), 0.5 mL EDTA (6 mM), 1 mL pyrogallol (6 mM) and 0.1 mL enzyme extract, and changes in absorbance at 420 nm were recorded every 30 s for 3 min. PAL activity was determined using a cinnamic acid standard curve following Bajaj et al. (2024) by incubating 0.1 mL enzyme extract with 2.5 mL phenylalanine (0.03 M) in sodium borate buffer (0.05 M, pH 8.8) at 37°C for 1 h, terminating the reaction with 0.3 mL 1 N HCl and measuring absorbance at 290 nm. Statistical analysis A randomized block design was utilized to examine data collected at the time of harvest for studies on quality improvement. The data was analyzed for variance using SAS (version 9.3, SAS Institute Inc., USA) and the treatment means were separated using LSD (p≤0.05). Results The foliar application of GABA significantly improved berry physical characteristics during both years of study (Table 1). Berry length increased markedly with increasing GABA concentration and ranged from 14.99 mm (control) to 18.96 mm (T3) in 2024 and 15.76 mm (control) to 19.76 (T3) mm in 2025. Briefly, the maximum berry length during both years were recorded with GABA @100 mM, which was statistically at par with GABA @50 mM (18.46 mm and 18.81 mm) but significantly superior to GABA @25 mM and the control. A similar trend was observed in berry diameter, where the highest values (18.43 mm and 18.75 mm) were obtained under GABA @ 100 mM followed by GABA @50mM, showing significant improvement over the control vines (14.82 mm and 14.95 mm). Regarding the berry weight, the highest values (2.99 g and 3.18 g) was recorded with GABA @ 100 mM, followed by 50 mM, whereas the lowest berry weight was observed in untreated vines (2.51g and 2.68g). Regarding the visual appearance, berry colour parameters were markedly affected by GABA application (Table 2). The L* value decreased significantly compared to the control, indicating development of deeper coloration. The lowest L* values (35.54 and 34.32) were recorded under 50 mM during both seasons. Conversely, a* values increased significantly with increasing GABA concentration, with maximum redness observed with 100 mM GABA (15.35 and 15.91), followed by 50 mM, whereas the control recorded the lowest a* values (11.46 and 10.06). The b* values showed a decreasing trend, with minimum values (11.53 and 11.16) observed with GABA @100mM as compared to control (13.70 and 14.21) followed closely by T2, suggesting a shift from yellowish tones towards more desirable red pigmentation. Similarly the results clearly demonstrated the positive impact of GABA on cluster traits (Table 3). Vines treated with 100 mM GABA produced significantly longer clusters (21.38 and 22.33 cm) than the control (15.66 and 16.99 cm) followed by 50mM GABA during 2024 and 2025 respectively. Similarly, cluster width under T3 (18.68 and 18.95 cm) was markedly higher than in untreated vines (14.58 and 15.24 cm). Cluster weight followed the same trend, with T3 recording 366.87 and 370.37 g compared to 316.57 and 320.15 g in the control, which corresponds to an increase of nearly 15.9% in 2024 and 15.7% in 2025 respectively. The foliar application of GABA also exerted a significant influence on both yield and quality attributes, with responses varying according to concentration. In terms of yield (Figure 1), higher GABA concentrations consistently outperformed the control in both years. In 2024, the highest yield was recorded with 100 mM GABA (27.78 kg vine⁻¹), which was statistically superior to the control (24.15 kg/vine) and at par with 50 mM. A similar pattern was observed in 2025, where 100 mM GABA resulted in the maximum yield (28.64 kg/vine), significantly surpassing all other treatments, followed by 25 mM and 50 mM, but significantly higher than the control (24.77 kg/vine). In contrast, TSS responded optimally to a moderate GABA concentration across both seasons, indicating a distinct quality response (Figure 1). During 2024, TSS ranged from 16.08 to 19.70 °Brix, with 50 mM GABA recording the highest value, statistically superior to the control and 25 mM treatment and at par with 100 mM. This trend was consistent in 2025, where TSS varied from 16.93 to 20.25 °Brix, with 50 mM again producing the highest TSS (20.25 °Brix), statistically superior to 25 mM and the control, and at par with 100 mM (19.28 °Brix). Overall, these results demonstrate that while higher concentration (100 mM) was most effective in maximizing vine productivity, a moderate concentration (50 mM) was optimal for enhancing berry sugar accumulation, highlighting a concentration-dependent and trait-specific response to exogenous GABA application. Regarding the antioxidant defense mechanisms, moderate to high concentrations (50-100 mM) were most effective as indicated by improved total phenolic content and antioxidant capacity (Figure 2). In 2024, TPC ranged from 65.93 to 79.78 mg GAE/100g FW, with the highest value recorded in 100mM, which was statistically at par with 50mM. 25mM showed a moderate response, while the control recorded the lowest phenolic content. A similar trend was observed in 2025, when phenolic content ranged from 68.00 to 82.08 mg GAE/100g FW, with 100mM again producing the highest value, followed by 50mM and 25mM, whereas control remained significantly inferior. Correspondingly, DPPH radical scavenging activity followed the same treatment hierarchy across both seasons, reinforcing the close association between phenolic accumulation and antioxidant potential. In 2024, antioxidant activity varied from 63.10 to 74.20%, with 100mM recording the highest activity, followed by 50 and 25 mM, while control exhibited the lowest value. This pattern was consistently reproduced in 2025, where T3 again showed maximum activity (76.93%), followed by T2 (73.77%) and T1 (71.77%), with T4 remaining significantly lower (63.63%). Total anthocyanin content also varied markedly among treatments in both years, ranging from 30.31 to 35.63 mg/100g FW in 2024 and from 28.58 to 36.47 mg/100 g FW in 2025 (Figure 3). In both seasons, T2 recorded the highest anthocyanin content and remained statistically at par with T3, while T1 showed intermediate values, indicating a moderate response to GABA application. In contrast, the control consistently recorded the lowest anthocyanin content. A parallel trend was observed for PAL activity, which ranged from 6.23 to 8.44 U/mg protein in 2024 and from 6.33 to 8.63 U/mg protein in 2025 (Figure 3). In both years, T3 exhibited the highest PAL activity and was statistically at par with, whereas T4 recorded the lowest enzyme activity. CAT activity ranged from 11.63 to 15.23 U/mg protein in 2024, with the highest activity recorded in T3, which was statistically at par with T2, while the control recorded the lowest value (Figure 4). A similar trend was observed in 2025, where CAT activity varied from 12.33 to 15.35 U/mg protein, with T3 and T2 again forming the top statistical group, followed by T1 and T4. SOD activity followed an analogous pattern across both seasons, reinforcing the overall enhancement of antioxidant defense system. In 2024, SOD activity ranged from 6.61 to 8.71 U/mg protein, with T3 recording the highest activity, statistically at par with T2, while T1 exhibited intermediate activity and T4 the lowest (Figure 4). This response was consistently reproduced in 2025, where SOD activity varied from 6.74 to 8.84 U/mg protein, with T3 and T2 remaining statistically superior to other treatments, followed by T1 and T4. Overall, the stable treatment ranking over two seasons indicates that moderate to high GABA concentrations (50-100 Mm) most effectively enhanced PAL, CAT and SOD activities, suggesting improved ROS scavenging and strengthened oxidative stress tolerance in berries. Discussion While most research has emphasized postharvest GABA applications, evidence for preharvest usage remains sparse. However, the current findings demonstrate that preharvest foliar GABA significantly improves yield and yield-related characteristics in grape berries. Among the treatments, 100 mM (followed by 50 mM) was the most beneficial, considerably improving cluster length, breadth and weight through enhanced rachis growth, berry enlargement and assimilate accumulation. These effects are attributed to GABA's role as a metabolic regulator and signalling molecule, in which the GABA shunt supplies succinate for mitochondrial respiration, increases ATP availability for cell division and elongation, thereby favouring carbohydrate translocation and dry matter accumulation in clusters (Bouché and Fromm 2004; Kinnersley and Turano 2000; Carillo P 2018). Consequently, berry weight, length and diameter increased primarily due to enhanced mesocarp cell expansion, as GABA-induced solute accumulation lowers cellular water potential, increases turgor pressure and improves water retention through partial stomatal closure (Mohamed et al. 2019; Hayat et al. 2023). Improved berry size, decreased fruit drop, increased photo-assimilate accumulation and improved photosynthetic performance all contributed to higher yield per vine, which was consistent with previous findings in grape cv. Qızıl Uzum, lemon cv. Fino, pomegranate cv. Mollar de Elche and strawberry cv. Camarosa (Allahveran et al. 2023;Badiche et al. 2023;Lorente-Mento et al. 2023; Soukht-Saraei et al 2024). In addition, GABA treatments significantly improved TSS with 50 mM being most effective, which is consistent with reports in strawberry and sweet cherry where GABA modulated sugar and organic acid metabolism enhanced TSS, TA and firmness, thereby improving internal quality and postharvest performance (Zhang et al. 2024;Carrión-Antolí et al. 2023). Fruit colour is a key quality attribute determining consumer acceptance, as it is the first visual trait perceived by consumers (Suehiro et al. 2029). In grapes, red colour development results from chlorophyll degradation and anthocyanins accumulation, which begins at the onset of ripening and coincides with increased sugar and aroma compounds (Marco et al. 2027;Kuhn et al. 2014). Anthocyanin synthesis is strongly influenced by environmental factors, particularly temperature and light, with high temperatures during ripening often causing poor coloration. In the present study, treated grapes exhibited superior visual quality compared with the control, likely due to GABA-mediated preservation of antioxidant activity and delayed quality deterioration. Similar effects of exogenous GABA have been reported in bananas where 20 mM GABA slowed decline in peel L* and h° and chinese olives where 1 mM GABA delayed h° reduction and de-greening (Wang et al. 2014;Fan et al. 2022). Moreover, GABA application in strawberry enhanced anthocyanin, flavonoid contents and antioxidant capacity, further supporting its role in improving fruit colour and visual quality (Zhang et al. 2024). Phenolic compounds, including flavonoids (flavonols, flavones, flavanones, isoflavones and anthocyanins) and non-flavonoids (phenolic acids, tannins, stilbenes and lignans), are abundant in grapes (Bellincontro et al. 2006). In the present study, preharvest GABA @ 100 mM, led to maximum accumulation of total phenolics, likely through regulation of secondary metabolism, stress signalling and ripening-related gene expression. The enhanced retention of these bioactive compounds is mainly associated with higher PAL activity, which limit oxidative degradation and strengthen ROS scavenging capacity. Comparable increases in total phenolics following GABA application have been reported in Cornelian cherry, aonla, strawberry, carambola, persimmon and blood orange, supporting GABA’s role in enhancing antioxidant potential and mitigating ROS-induced oxidative damage (Ma et al. 2019;Aghdam et al. 2019;Ali et al. 2022;Zhang et al. 2024;Ngaffo et al. 2021;Niazi et al. 2021;Habibi et al.2019). Increasing evidence suggests that exogenous GABA enhances the fruit antioxidant system by stimulating key enzymes (SOD, CAT, PAL), likely through ROS-mediated signalling in which transient H₂O₂ accumulation acts as a secondary messenger to activate redox homeostasis pathways (Hayat et al. 2023; Jin et al. 2023). In the present study, GABA significantly increased antioxidant enzyme activities, with maximum responses at 100 mM, indicating a strengthened antioxidative defence that helps maintain cellular integrity, support phenolic metabolism, reinforce cell walls and delay senescence. The involvement of GABA in the GABA shunt further contributes to energy metabolism and redox balance, indirectly improving antioxidant efficiency (Seifikalhor et al. 2019). Concurrently, GABA enhanced PAL activity, the key entry enzyme of the phenylpropanoid pathway responsible for the biosynthesis of phenolics, including anthocyanins (Singh et al. 2010). Similar GABA-induced enhancement of antioxidant enzymes has been reported in strawberry, papaya, aonla and sweet cherry, where elevated SOD, CAT and PAL activities improved ROS detoxification, delayed ripening and senescence and extended storage life (Ali et al. 2022;Zhang et al. 2024; Khaliq et al. 2023; Carrión-Antolí et al. 2023; Ali et al. 2025). Collectively, these findings confirm that GABA application effectively primes the fruit antioxidant system, thereby reducing oxidative stress and improving fruit quality. Conclusion The findings highlight the potential of GABA as a climate-resilient biostimulant for improving productivity, fruit quality and nutraceutical value in table grapes under subtropical conditions. GABA @50 mM resulted in highest TSS, lowest L* and maximum total anthocyanin content, whereas 100 mM was most effective in enhancing cluster morphological traits, including length, width and weight along with berry size, weight and overall yield. Improved colour parameters, characterized by higher a* and lower b* values further indicated enhanced berry pigmentation and marketable quality. In addition, it promoted the accumulation of bioactive compounds, reflected by increased TPC and enhanced activities of key ROS-scavenging enzymes (SOD, CAT and PAL), suggesting improved antioxidant potential through reduced H₂O₂ and MDA levels, better membrane stability and delayed senescence. Future prospects include integrating GABA into precision nutrient management and deficit irrigation strategies, elucidating its molecular regulation of anthocyanin biosynthesis and stress signaling pathways and validating its effectiveness through multi-location trials to develop standardized recommendations for sustainable viticulture. Abbreviations GABA: γ-aminobutyric acid; CAT: Catalase; PAL: phenylalanine ammonia-lyase; SOD: superoxide dismutase; TCA: Tricarboxylic acid cycle; GAE: gallic acid equivalents; FCR: Folin–Ciocalteu reagent Declarations Acknowledgements The authors are thankful to Punjab Agricultural University, Ludhiana, India for providing the necessary research facilities Funding This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors. Statements and Declarations Conflict of interest The authors declare that they have no conflict of interest. Author Contricutions Khushi Kumari: Writing – original draft, Investigation, Formal analysis, Data curation. Rachna Arora: Writing – review & editing, Conceptualization. Naresh Kumar Arora: Resources. Shalini Jhanji: Methodology, Conceptualization Jaswinder Singh Brar: Resources. 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Bajaj K, Kumar A, Gill P P S, Jawandha S K and Kaur N (2024) Xanthan gum coatings augmented with lemongrass oil preserve postharvest quality and antioxidant defence system of Kinnow fruit under low-temperature storage. Int J Biol Macromol. 262:129776. https://doi.org/10.1016/j.ijbiomac.2024.129776 Bouché N and Fromm H (2004) GABA in plants: Just a metabolite? Trends Plant Sci . 9(3):110-15. 10.1016/j.tplants.2004.01.006 Kinnersley A M and Turano F J (2000) Gamma aminobutyric acid (GABA) and plant responses to stress. Crit Rev Plant Sci. 19(6):479–509. https://doi.org/10.1080/07352680091139277 Carillo P (2018) GABA shunt in durum wheat. Front Plant Sci. 9:101-12. https://doi.org/10.3389/fpls.2018.00100 Mohamed A, El-Salhy A, Mostafa R, El-Mahdy M and Hussein A (2019) Effect of Exogenous Abscisic Acid (ABA), Gibberellic Acid (GA3) and Cluster Thinning on Yield of some Grape Cultivars. J Plant Prod. 10(2):101-05. Hayat F, Khan U, Li J, Ahmed N, Khanum F, Iqbal S and Shahid M A (2023) γ Aminobutyric acid (GABA): a key player in alleviating abiotic stress resistance in horticultural crops: current insights and future directions. Horticulturae. 9(6):647. https://doi.org/10.3390/horticulturae9060647 Allahveran Oosalo A, Naseri L, Alirezalu A, Darvishzadeh R and Nejad Ebrahimi S (2023) The effect of gamma aminobutyric acid (GABA) foliar application on some biochemical characteristics and expression pattern of PAL and CHS genes in Qızıl Uzum grape ( Vitis vinifera L.). J Plant Prod Res. 30(1):125-48. 10.22069/JOPP.2022.20280.2938 Lorente-Mento J M, Guillén F, Martínez-Romero D, Carrión-Antoli A, Valero D and Serrano M (2023) γ-Aminobutyric acid treatments of pomegranate trees increase crop yield and fruit quality at harvest. 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Food Chemistry. 13:100208. https://doi.org/10.1016/j.fochx.2022.100208 Bellincontro A, Fardelli A, De Santis D, Botondi R and Mencarelli F (2006) Postharvest ethylene and 1-MCP treatments both affect phenols, anthocyanins, and aromatic quality of Aleatico grapes and wine. Aust J Grape Wine Res. 12(2):141-49. https://doi.org/10.1111/j.1755-0238.2006.tb00054.x Ma Y, Wang P, Wang M, Sun M, Gu Z and Yang R (2019) GABA mediates phenolic compounds accumulation and the antioxidant system enhancement in germinated hulless barley under NaCl stress. Food Chem. 270:593-601. https://doi.org/10.1016/j.foodchem.2018.07.092 Ali S, Anjum M A, Nawaz A, Ejaz S, Anwar R, Khaliq G et al. (2022) Postharvest γ-aminobutyric acid application mitigates chilling injury of aonla ( Emblica officinalis Gaertn.) fruit during low temperature storage. Postharvest Biol Technol. 185:111803. https://doi.org/10.1016/j.postharvbio.2021.111803 Ngaffo Mekontso F, Duan W, Cisse E H M, Chen T and Xu X (2021) Alleviation of postharvest chilling injury of carambola fruit by γ-aminobutyric acid: physiological, biochemical, and structural characterization. Frontiers in Nutrition. 8:752583. https://doi.org/10.3389/fnut.2021.752583 Niazi Z, Razavi F, Khademi O and Aghdam M S (2021) Exogenous application of hydrogen sulfide and γ-aminobutyric acid alleviates chilling injury and preserves quality of persimmon fruit ( Diospyros kaki , cv. Karaj) during cold storage. Sci Hortic . 285:110198. https://doi.org/10.1016/j.scienta.2021.110198 Habibi F, Ramezanian A, Rahemi M, Eshghi S, Guill´en F, Serrano M and Valero D (2019) Post-harvest treatments with γ-aminobutyric acid, methyl jasmonate, or methyl salicylate enhance chilling tolerance of blood orange fruit at prolonged cold storage. J Sci Food Agric. 99(14):6408-17. https://doi.org/10.1002/jsfa.9920 Jin Y, Zhi L, Tang X, Chen Y, Hancock J and Hu X (2023) The function of GABA in plant cell growth, development and stress response. Phyton. 92(8):2211. 10.32604/phyton.2023.026595 Seifikalhor M, Aliniaeifard S, Hassani B, Niknam V and Lastochkina O (2019) Diverse role of γ-aminobutyric acid in dynamic plant cell responses. Plant Cell Rep. 38(8):847-67. https://doi.org/10.1007/s00299-019-02396-z Singh R, Rastogi S and Dwivedi U N (2010) Phenylpropanoid Metabolism in Ripening Fruits. Compr Rev Food Sci Food Saf. 9(4):398-416. https://doi.org/10.1111/j.1541-4337.2010.00116.x Khaliq G, Ali S, Ejaz S, Abdi G, Faqir Y, Ma J and Ali A (2023) γ-Aminobutyric acid is involved in overlapping pathways against chilling injury by modulating glutamate decarboxylase and defense responses in papaya fruit. Front Plant Sci. 14:1233477. https://doi.org/10.3389/fpls.2023.1233477 Ali M A, Ayvaz Sonmez D and Kafkas E (2025) Enhancement of Antioxidant Defense Mechanism by Preharvest Gaba Spray on Postharvest Quality of Strawberries. Horticulturae. 11:170-84. Tables Table 1. Effect of GABA on berry length (mm), diameter (mm) and weight (g) of grape cv. Flame Seedless Treatment Berry length (mm) Berry diameter (mm) Berry weight (g) 2024 2025 2024 2025 2024 2025 T1 (GABA @25 mM) 17.13±0.9b 17.48±0.9bc 16.38±0.2b 16.89±0.3b 2.79±0.04b 2.84±0.19bc T2 (GABA @50 mM) 18.46±0.2ab 18.81±0.3ab 17.91±0.3a 18.14±0.3a 2.88±0.04ab 3.03±0.05ab T3 (GABA @100 mM) 18.96±0.5a 19.76±0.7a 18.43±0.4a 18.75±0.3a 2.99±0.04a 3.18±0.06a T4 (Control) 14.99±0.4c 15.76±0.4c 14.82±0.2c 14.95±0.3c 2.51±0.03c 2.68±0.04c LSD (p< 0.05) 1.76 1.83 0.85 0.92 0.13 0.34 Table 2. Effect of GABA on fruit colour index (L*, a* and b*) of grape cv. Flame Seedless Treatment L* a* b* 2024 2025 2024 2025 2024 2025 T1 (GABA @25 mM) 40.22±0.6b 39.09±0.9b 12.96±0.2c 13.54±0.2b 13.17±0.3ab 13.04±0.6b T2 (GABA @50 mM) 35.54±0.4d 34.32±0.5c 14.19±0.2b 14.88±0.2a 12.11±0.4bc 11.91±0.2c T3 (GABA @100 mM) 37.99±0.5c 37.61±0.5b 15.36±0.3a 15.91±0.4a 11.54±0.1c 11.17±0.3c T4 (Control) 44.36±0.3a 43.6±1.2a 11.46±0.4d 10.07±0.5c 13.70±0.5a 14.22±0.2b LSD (p<.05) 1.35 1.47 0.86 0.86 1.13 1.08 Table 3. Effect of GABA on cluster length (cm), width (cm) and weight (g) of grape cv. Flame Seedless Treatment Cluster length (cm) Cluster width (cm) Cluster weight (g) 2024 2025 2024 2025 2024 2025 T1 (GABA @25 mM) 18.08±0.2b 20.27±0.3b 16.1±0.3b 17.24±0.5b 340.67±7.7b 348.78±3.8b T2 (GABA @50 mM) 19.96±0.3a 21.16±0.4ab 17.31±0.3b 18.13±0.2ab 357.8±4.0a 361.67±4.2a T3 (GABA @100 mM) 21.38±0.8a 22.33±0.7a 18.68±0.2a 18.95±0.3a 366.87±4.0a 370.37±4.7a T4 (Control) 15.66±0.7c 16.99±0.8c 14.58±0.7c 15.24±0.3c 316.57±2.8c 320.15±2.7c LSD (p<.05) 1.73 1.79 1.34 1.08 15.48 12.02 Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9036075","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":604298278,"identity":"e8bc698a-5a80-458a-9926-64fcc7d9cdb9","order_by":0,"name":"Khushi Kumari","email":"","orcid":"","institution":"Punjab Agricultural University","correspondingAuthor":false,"prefix":"","firstName":"Khushi","middleName":"","lastName":"Kumari","suffix":""},{"id":604298279,"identity":"37a6e52a-07d0-4071-b111-3d2969ff6e16","order_by":1,"name":"Rachna 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1","display":"","copyAsset":false,"role":"figure","size":40940,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of GABA treatments on yield (kg/vine) and TSS (°Brix) of grapes \u003cem\u003ecv. \u003c/em\u003eFlame Seedless\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-9036075/v1/4403e978268262ca10e1e1c1.png"},{"id":104781084,"identity":"ddc71385-1cbc-41a2-9f01-b915f83e3b36","added_by":"auto","created_at":"2026-03-17 07:54:41","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":47861,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of GABA treatments on total phenolics (mg GAE/100g FW) and antioxidants (%) of grapes \u003cem\u003ecv. \u003c/em\u003eFlame Seedless\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-9036075/v1/8e561f8ba48f08a151fc14ab.png"},{"id":104499469,"identity":"19a0389e-226a-43a5-822d-38762873f321","added_by":"auto","created_at":"2026-03-12 13:31:09","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":42387,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of GABA treatments on total anthocyanins (mg/100g FW) and PAL activity (U/mg protein) of grapes \u003cem\u003ecv. \u003c/em\u003eFlame Seedless\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-9036075/v1/889da0d367fa3ee5822e4340.png"},{"id":104499467,"identity":"5da320a2-d5aa-480d-b3d8-b68fa4569a81","added_by":"auto","created_at":"2026-03-12 13:31:09","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":42133,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of GABA treatments on CAT activity (U/mg protein) and SOD activity (U/mg protein) of grapes \u003cem\u003ecv. \u003c/em\u003eFlame Seedless\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-9036075/v1/01d5bd5b0f07d42bda03de9b.png"},{"id":104786915,"identity":"70dfad3d-eb4c-440b-a3f0-28063e4c505e","added_by":"auto","created_at":"2026-03-17 08:18:49","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":976101,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9036075/v1/ca13652a-04a6-4381-8e42-f512c2df2a28.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Elevating Berry Excellence: GABA-Induced Stimulation of Anthocyanin Biosynthesis and Antioxidant Defense in Flame Seedless Grapes","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe grapevine (\u003cem\u003eVitis vinifera\u003c/em\u003e L.) belongs to the family Vitaceae which consists of 12 genera and 600 species. Due to its extensive global cultivation, it is regarded as one of the most economically significant fruit crops. Besides carbohydrates (17 g/100 g), grapes also have a high caloric content (65 kcal/100 g) and a relatively low glycemic index. Apart from being a superb provider of K and Mn, they also contain a considerable amount of vitamin B1, B6 and C (Unusan N \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). It has a variety of bioactive substances, the amounts of which can vary greatly in grape skin, pulp and seed. These include proanthocyanidins, anthocyanins, flavonols, phenolic acids and stilbenes. Numerous studies have demonstrated many health benefits associated with grapes, including their anti-inflammatory, anti-tumor, gut-microbiota-modulating, antioxidant and cardioprotective properties (Zhou et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe commercial value of grapes \u003cem\u003ecv.\u003c/em\u003e Flame Seedless, created by J. Weinberger and F. Harmon in 1989 is determined by their form, cluster size, quality and attractiveness (Abdel-Sattar et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Although this is superior to many other variants in terms of its crimson red color, seedless berries, high TSS:Acid, medium bunch size and extended shelf life, the major obstacle to grow it is uneven berry pigmentation which is best facilitated by summer's high temperatures and sugar content resulting in diminished anthocyanins synthesis (Akram et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Since uniform, bright red berries are associated with ripeness, sweetness and superior quality, uneven colour often creates a perception of inferior fruit even when internal quality is acceptable. For farmers, this directly translates into increased sorting and labour costs, postharvest losses and rejection in premium export markets. Since there is little ability to regulate the climate in open fields, alternative methods of regulating colour development and antioxidant capacity must be investigated. In recent years various plant growth stimulants have been used to improve grape colour, chemical contents and other quality parameters.\u003c/p\u003e \u003cp\u003eFirst discovered in potato tubers, a water soluble, non-protein amino acid with four carbon atoms and an amino group on the γ-carbon, GABA may be used as an effective technique to enhance the quality of horticultural crops due to its capacity to develop stress tolerance (Li et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2021\u003c/span\u003e;Kawade et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). It builds up as a result of plant reactions to environmental stressors, increasing the plant stress tolerance through enhanced photosynthesis, triggering antioxidant enzymes and controlling stomatal opening during drought stress (Li et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). It has been extensively investigated in animal central nervous systems where it functions as an inhibitory neurotransmitter while in plants, it is broken down via the GABA shunt pathway, a bypass of the TCA cycle, in which the glutamate decarboxylase enzyme converts glutamate into GABA. It functions as a signal in \u003cem\u003eAgrobacterium tumefaciens\u003c/em\u003e-mediated plant gene transformation and in plant development (root growth, fruit ripening, seed germination and pollen tube elongation) as well as regulates a number of physiological processes, including senescence, cytosolic pH, redox status and osmotic moiety. At the molecular level, the cytosolic GABA shunt functions as a signaling molecule, scavenging ROS and shielding the plant from oxidative harm (Badiche et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eMore recently, a variety of fruit species, including table grape, cornelian, mango and kiwifruit have been shown to be benefitted from postharvest GABA treatments in terms of preserving quality attributes (Asgarian et al. \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Aghdam et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Rastegar et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Liu et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). As GABA increases antioxidant enzymes, it has been demonstrated to be a successful method for maintaining postharvest quality and improving the storage performance of bananas, citrus, cucumber and peaches (Wang et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Sheng et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Malekzadeh et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Aghdam et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Shang et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Yang et al \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). Exogenously administered GABA can raise endogenous GABA levels, which has positive effects on plant growth and development similar to intrinsically formed molecule (Ramos-Ruiz et al. \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Without changing fruit hardness, total soluble solids or titratable acidity, GABA treatment in lemon \u003cem\u003ecv.\u003c/em\u003e Fino-95 enhanced crop yield (Badiche et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Moreover, applying a GABA foliar spray to apple trees one or two weeks prior to harvest reduced the symptoms of soft scald following cold storage (Al-Shoffe et al. 2021). Based on prior research, the primary objective of the current investigation was to test the hypothesis that preharvest GABA treatments could improve table grape \u003cem\u003ecv\u003c/em\u003e. Flame Seedless quality characteristics, particularly anthocyanin accumulation and antioxidant potential at harvest.\u003c/p\u003e"},{"header":"Material and Methods","content":"\u003cp\u003e\u003cstrong\u003ePlant material and treatments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDuring two consecutive cropping seasons (2023\u0026ndash;2024 and 2024\u0026ndash;2025), the present investigation was conducted on 17-years-old own-rooted vines of table grape (\u003cem\u003eVitis vinifera\u003c/em\u003e L.) \u003cem\u003ecv.\u003c/em\u003e Flame Seedless at the Fruit Research Farm, Department of Fruit Science, Punjab Agricultural University (PAU), Ludhiana, Punjab, India. The soil contained 121g clay, 146g silt and 721g sand/kg with a pH of 8.1 and was salinity-free (0.30 dS/m). It possessed medium organic carbon (4.3 g OC/kg), 25.8 mg extractable P/kg and 319.5 mg NH4OAc-extractable K/kg. The vines were grown in sandy soil under a drip irrigation system and trained on a bower system at a spacing of 3 \u0026times; 3 m. A total of 16 uniform vines were selected randomly and divided into four treatments, each comprising of four vines. At the onset of veraison, a crucial turning point characterised by significant changes to the cell wall, a sharp rise in sugar content, a decrease in acidity and a change in skin coloration (accumulation of anthocyanins and a change from green to red), bunches from the first three treatments were sprayed with\u0026nbsp;GABA @ 25 mM (T1), 50 mM (T2) and 100 mM (T3), each prepared with 0.1% (v/v) Tween 80 as a surfactant. The fourth treatment (T4) served as the control. Each vine represented one replication, resulting in four replications per treatment. Grape samples were harvested at the commercial maturity stage and immediately transported to the Postgraduate Laboratory, PAU, Ludhiana. For physico-chemical evaluation, a total sample of 4 kg per treatment (1 kg per vine) was collected, cleaned off the dirt immediately and analysed for various parameters following standard procedures, as described below.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFruit yield and physical attributes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOverall yield (kg/vine) was estimated by multiplying the average cluster weight per vine with the total number of clusters per vine. Cluster length and width (cm) were measured using a measuring scale, while cluster weight (g) and berry weight (g) were recorded using an electronic balance. Berry diameter and length (mm) were measured with a vernier calliper.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eFruit colour was measured colorimetrically on two opposite equatorial sides of thirty berries per treatment using a Minolta colorimeter (Minolta Co. Ltd., Osaka, Japan). The brightness of the fruit surface is represented by the L* (lightness) values, which range from 0 (black) to 100 (white). On the other hand, positive values for a* correspond to red and negative values to green. Similarly positive values for b* indicate yellow and negative values for blue.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eBiochemical attributes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTSS was measured at room temperature using a Bausch and Lomb hand refractometer and expressed as \u0026deg;Brix, with values corrected to 20 \u0026deg;C using a temperature correction table. Total phenolic content was determined by Folin\u0026ndash;Ciocalteu reagent (FCR) method using a gallic acid standard curve and expressed as mg gallic acid equivalents (GAE)/100 g FW as described by Malik and Singh (1980). Briefly, 1 mL of fruit methanolic extract was evaporated at 70\u0026ndash;75\u0026deg;C, mixed with 6.5 mL of deionized water and 0.5 mL of FCR, and after 5 min, 1 mL of saturated sodium carbonate solution (35 g/100 mL water) was added. The mixture was incubated in the dark for 1 h for development of a dark blue colour and absorbance was recorded at 760 nm against a blank of FCR diluted with distilled water (1:1). Total anthocyanin content was determined following the method of Fuleki and Francis (1968), in which 5 g of crushed fruit peel was extracted with 100 mL of reagent A (95% ethanol and 0.1 N HCl, 85:15) and stored overnight at 4\u0026deg;C. After 4\u0026ndash;5 filtrations, the volume was adjusted to 100 mL with reagent A, and a 10 mL aliquot was kept in the dark for 24 h. For estimation, 10 mL of reagent A was added to the aliquot, and absorbance was recorded at 535 nm against a reagent A blank. Total anthocyanin content (mg/g FW) was calculated using the formula:\u003c/p\u003e\n\u003cp\u003e\u003cimg src=\"https://myfiles.space/user_files/58895_8739fc6c57c1c19a/58895_custom_files/img1773321833.png\" width=\"695\" height=\"73\"\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAntioxidative defense enzyme activities\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAntioxidant activity was assessed using the DPPH radical scavenging assay described by Blois (1958). A reaction mixture containing 0.1 mL of methanolic fruit extract and 0.29 mL of 0.1 mM DPPH solution was incubated in the dark for 30 min and absorbance was recorded at 517 nm using a control. Radical scavenging activity (%) was calculated as \u003cimg width=\"113\" height=\"34\" src=\"https://myfiles.space/user_files/58895_8739fc6c57c1c19a/58895_custom_files/img1773321846.png\" alt=\"image\"\u003e, where \u003cimg width=\"14\" height=\"34\" src=\"https://myfiles.space/user_files/58895_8739fc6c57c1c19a/58895_custom_files/img177332184631.png\" alt=\"image\"\u003e\u0026nbsp;and \u003cimg width=\"14\" height=\"34\" src=\"https://myfiles.space/user_files/58895_8739fc6c57c1c19a/58895_custom_files/img177332184629.png\" alt=\"image\"\u003e represent the absorbance of the control and sample, respectively. For CAT, enzyme was extracted by homogenizing 0.1 g fruit tissue in 2 mL of cold sodium phosphate buffer (pH 7.5), followed by centrifugation at 10,000 rpm for 30 min at 4\u0026deg;C. The enzymatic activity was measured according to Rukunuzzaman et al. (2025) by adding 1 mL H₂O₂ solution (diluting 0.2 mL of 30% H₂O₂ to 50 mL with 50 mM sodium phosphate buffer, pH 7.5) to a reaction mixture containing 1.8 mL buffer and 0.2 mL enzyme extract, and monitoring the optical density at 240 nm every 30 s for 3 min. SOD activity was assayed following Marklund and Marklund (1974)\u003csup\u003e\u0026nbsp;\u003c/sup\u003ebased on inhibition of pyrogallol auto-oxidation, where the reaction mixture contained 1.5 mL Tris-HCl buffer (0.1 M, pH 8.2), 0.5 mL EDTA (6 mM), 1 mL pyrogallol (6 mM) and 0.1 mL enzyme extract, and changes in absorbance at 420 nm were recorded every 30 s for 3 min. PAL activity was determined using a cinnamic acid standard curve following Bajaj et al. (2024) by incubating 0.1 mL enzyme extract with 2.5 mL phenylalanine (0.03 M) in sodium borate buffer (0.05 M, pH 8.8) at 37\u0026deg;C for 1 h, terminating the reaction with 0.3 mL 1 N HCl and measuring absorbance at 290 nm.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA randomized block design was utilized to examine data collected at the time of harvest for studies on quality improvement. The data was analyzed for variance using SAS (version 9.3, SAS Institute Inc., USA) and the treatment means were separated using LSD (p\u0026le;0.05).\u0026nbsp;\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eThe foliar application of GABA significantly improved berry physical characteristics during both years of study (Table 1). Berry length increased markedly with increasing GABA concentration and ranged from 14.99 mm (control) to 18.96 mm (T3) in 2024 and 15.76 mm (control) to 19.76 (T3) mm in 2025. Briefly, the maximum berry length during both years were recorded with GABA @100 mM, which was statistically at par with GABA @50 mM (18.46 mm and 18.81 mm) but significantly superior to \u0026nbsp;GABA @25 mM and the control. A similar trend was observed in berry diameter, where the highest values (18.43 mm and 18.75 mm) were obtained under GABA @ 100 mM followed by GABA @50mM, showing significant improvement over the control vines (14.82 mm and 14.95 mm). Regarding the berry weight, the highest values (2.99 g and 3.18 g) was recorded with GABA @ 100 mM, followed by 50 mM, whereas the lowest berry weight was observed in untreated vines (2.51g and 2.68g). Regarding the visual appearance, berry colour parameters were markedly affected by GABA application (Table 2). The L* value decreased significantly compared to the control, indicating development of deeper coloration. The lowest L* values (35.54 and 34.32) were recorded under 50 mM during both seasons. Conversely, a* values increased significantly with increasing GABA concentration, with maximum redness observed with 100 mM GABA (15.35 and 15.91), followed by 50 mM, whereas the control recorded the lowest a* values (11.46 and 10.06). The b* values showed a decreasing trend, with minimum values (11.53 and 11.16) observed with GABA @100mM as compared to control (13.70 and 14.21) followed closely by T2, suggesting a shift from yellowish tones towards more desirable red pigmentation. Similarly the results clearly demonstrated the positive impact of GABA on cluster traits (Table 3). Vines treated with 100 mM GABA produced significantly longer clusters (21.38 and 22.33 cm) than the control (15.66 and 16.99 cm) followed by 50mM GABA during 2024 and 2025 respectively. Similarly, cluster width under T3 (18.68 and 18.95 cm) was markedly higher than in untreated vines (14.58 and 15.24 cm). Cluster weight followed the same trend, with T3 recording 366.87 and 370.37 g compared to 316.57 and 320.15 g in the control, which corresponds to an increase of nearly 15.9% in 2024 and 15.7% in 2025 respectively.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe foliar application of GABA also exerted a significant influence on both yield and quality attributes, with responses varying according to concentration. In terms of yield (Figure 1), higher GABA concentrations consistently outperformed the control in both years. In 2024, the highest yield was recorded with 100 mM GABA (27.78 kg vine⁻\u0026sup1;), which was statistically superior to the control (24.15 kg/vine) and at par with 50 mM. A similar pattern was observed in 2025, where 100 mM GABA resulted in the maximum yield (28.64 kg/vine), significantly surpassing all other treatments, followed by 25 mM and 50 mM, but significantly higher than the control (24.77 kg/vine). In contrast, TSS responded optimally to a moderate GABA concentration across both seasons, indicating a distinct quality response (Figure 1). During 2024, TSS ranged from 16.08 to 19.70 \u0026deg;Brix, with 50 mM GABA recording the highest value, statistically superior to the control and 25 mM treatment and at par with 100 mM. This trend was consistent in 2025, where TSS varied from 16.93 to 20.25 \u0026deg;Brix, with 50 mM again producing the highest TSS (20.25 \u0026deg;Brix), statistically superior to 25 mM and the control, and at par with 100 mM (19.28 \u0026deg;Brix). Overall, these results demonstrate that while higher concentration (100 mM) was most effective in maximizing vine productivity, a moderate concentration (50 mM) was optimal for enhancing berry sugar accumulation, highlighting a concentration-dependent and trait-specific response to exogenous GABA application. Regarding the antioxidant defense mechanisms, moderate to high concentrations (50-100 mM) were most effective as indicated by improved total phenolic content and antioxidant capacity (Figure 2). In 2024, TPC ranged from 65.93 to 79.78 mg GAE/100g FW, with the highest value recorded in 100mM, which was statistically at par with 50mM. 25mM showed a moderate response, while the control recorded the lowest phenolic content. A similar trend was observed in 2025, when phenolic content ranged from 68.00 to 82.08 mg GAE/100g FW, with 100mM again producing the highest value, followed by 50mM and 25mM, whereas control remained significantly inferior. Correspondingly, DPPH radical scavenging activity followed the same treatment hierarchy across both seasons, reinforcing the close association between phenolic accumulation and antioxidant potential. In 2024, antioxidant activity varied from 63.10 to 74.20%, with 100mM recording the highest activity, followed by 50 and 25 mM, while control exhibited the lowest value. This pattern was consistently reproduced in 2025, where T3 again showed maximum activity (76.93%), followed by T2 (73.77%) and T1 (71.77%), with T4 remaining significantly lower (63.63%).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTotal anthocyanin content also varied markedly among treatments in both years, ranging from 30.31 to 35.63 mg/100g FW in 2024 and from 28.58 to 36.47 mg/100 g FW in 2025 (Figure 3). In both seasons, T2 recorded the highest anthocyanin content and remained statistically at par with T3, while T1 showed intermediate values, indicating a moderate response to GABA application. In contrast, the control consistently recorded the lowest anthocyanin content. A parallel trend was observed for PAL activity, which ranged from 6.23 to 8.44 U/mg protein in 2024 and from 6.33 to 8.63 U/mg protein in 2025 (Figure 3). In both years, T3 exhibited the highest PAL activity and was statistically at par with, whereas T4 recorded the lowest enzyme activity. CAT activity ranged from 11.63 to 15.23 U/mg protein in 2024, with the highest activity recorded in T3, which was statistically at par with T2, while the control recorded the lowest value (Figure 4). A similar trend was observed in 2025, where CAT activity varied from 12.33 to 15.35 U/mg protein, with T3 and T2 again forming the top statistical group, followed by T1 and T4. SOD activity followed an analogous pattern across both seasons, reinforcing the overall enhancement of antioxidant defense system. In 2024, SOD activity ranged from 6.61 to 8.71 U/mg protein, with T3 recording the highest activity, statistically at par with T2, while T1 exhibited intermediate activity and T4 the lowest (Figure 4). This response was consistently reproduced in 2025, where SOD activity varied from 6.74 to 8.84 U/mg protein, with T3 and T2 remaining statistically superior to other treatments, followed by T1 and T4. Overall, the stable treatment ranking over two seasons indicates that moderate to high GABA concentrations (50-100 Mm) most effectively enhanced PAL, CAT and SOD activities, suggesting improved ROS scavenging and strengthened oxidative stress tolerance in berries.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eWhile most research has emphasized postharvest GABA applications, evidence for preharvest usage remains sparse. However, the current findings demonstrate that preharvest foliar GABA significantly improves yield and yield-related characteristics in grape\u003cem\u003e\u0026nbsp;\u003c/em\u003eberries. Among the treatments, 100 mM (followed by 50 mM) was the most beneficial, considerably improving cluster length, breadth and weight through enhanced rachis growth, berry enlargement and assimilate accumulation. These effects are attributed to GABA\u0026apos;s role as a metabolic regulator and signalling molecule, in which the GABA shunt supplies succinate for mitochondrial respiration, increases ATP availability for cell division and elongation, thereby favouring carbohydrate translocation and dry matter accumulation in clusters (Bouch\u0026eacute; and Fromm 2004; Kinnersley and Turano 2000;\u0026nbsp;Carillo P 2018). Consequently, berry weight, length and diameter increased primarily due to enhanced mesocarp cell expansion, as GABA-induced solute accumulation lowers cellular water potential, increases turgor pressure and improves water retention through partial stomatal closure (Mohamed et al. 2019; Hayat et al. 2023). Improved berry size, decreased fruit drop, increased photo-assimilate accumulation and improved photosynthetic performance all contributed to higher yield per vine, which was consistent with previous findings in grape \u003cem\u003ecv.\u003c/em\u003e Qızıl Uzum, lemon \u003cem\u003ecv.\u003c/em\u003e Fino, pomegranate \u003cem\u003ecv.\u003c/em\u003e Mollar de Elche and strawberry \u003cem\u003ecv.\u003c/em\u003e Camarosa (Allahveran et al. 2023;Badiche et al. 2023;Lorente-Mento et al. 2023; Soukht-Saraei et al 2024). In addition, GABA treatments significantly improved TSS with 50 mM being most effective, which is consistent with reports in strawberry and sweet cherry where GABA modulated sugar and organic acid metabolism enhanced TSS, TA and firmness, thereby improving internal quality and postharvest performance (Zhang et al. 2024;Carri\u0026oacute;n-Antol\u0026iacute; et al. 2023). Fruit colour is a key quality attribute determining consumer acceptance, as it is the first visual trait perceived by consumers (Suehiro et al. 2029). In grapes, red colour development results from chlorophyll degradation and anthocyanins accumulation, which begins at the onset of ripening and coincides with increased sugar and aroma compounds (Marco et al. 2027;Kuhn et al. 2014). Anthocyanin synthesis is strongly influenced by environmental factors, particularly temperature and light, with high temperatures during ripening often causing poor coloration. In the present study, treated grapes exhibited superior visual quality compared with the control, likely due to GABA-mediated preservation of antioxidant activity and delayed quality deterioration. Similar effects of exogenous GABA have been reported in bananas where 20 mM GABA slowed decline in peel L* and h\u0026deg; and chinese olives where 1 mM GABA delayed h\u0026deg; reduction and de-greening (Wang et al. 2014;Fan et al. 2022). Moreover, GABA application in strawberry enhanced anthocyanin, flavonoid contents and antioxidant capacity, further supporting its role in improving fruit colour and visual quality (Zhang et al. 2024).\u003c/p\u003e\n\u003cp\u003ePhenolic compounds, including flavonoids (flavonols, flavones, flavanones, isoflavones and anthocyanins) and non-flavonoids (phenolic acids, tannins, stilbenes and lignans), are abundant in grapes (Bellincontro et al. 2006). In the present study, preharvest GABA @ 100 mM, led to maximum accumulation of total phenolics, likely through regulation of secondary metabolism, stress signalling and ripening-related gene expression. The enhanced retention of these bioactive compounds is mainly associated with higher PAL activity, which limit oxidative degradation and strengthen ROS scavenging capacity. Comparable increases in total phenolics following GABA application have been reported in Cornelian cherry, aonla, strawberry, carambola, persimmon and blood orange, supporting GABA\u0026rsquo;s role in enhancing antioxidant potential and mitigating ROS-induced oxidative damage (Ma et al. 2019;Aghdam et al. 2019;Ali et al. 2022;Zhang et al. 2024;Ngaffo et al. 2021;Niazi et al. 2021;Habibi et al.2019). Increasing evidence suggests that exogenous GABA enhances the fruit antioxidant system by stimulating key enzymes (SOD, CAT, PAL), likely through ROS-mediated signalling in which transient H₂O₂ accumulation acts as a secondary messenger to activate redox homeostasis pathways (Hayat et al. 2023; Jin et al. 2023). In the present study, GABA significantly increased antioxidant enzyme activities, with maximum responses at 100 mM, indicating a strengthened antioxidative defence that helps maintain cellular integrity, support phenolic metabolism, reinforce cell walls and delay senescence. The involvement of GABA in the GABA shunt further contributes to energy metabolism and redox balance, indirectly improving antioxidant efficiency (Seifikalhor et al. 2019). Concurrently, GABA enhanced PAL activity, the key entry enzyme of the phenylpropanoid pathway responsible for the biosynthesis of phenolics, including anthocyanins (Singh et al. 2010). Similar GABA-induced enhancement of antioxidant enzymes has been reported in strawberry, papaya, aonla and sweet cherry, where elevated SOD, CAT and PAL activities improved ROS detoxification, delayed ripening and senescence and extended storage life (Ali et al. 2022;Zhang et al. 2024; Khaliq et al. 2023; Carri\u0026oacute;n-Antol\u0026iacute; et al. 2023; Ali et al. 2025). Collectively, these findings confirm that GABA application effectively primes the fruit antioxidant system, thereby reducing oxidative stress and improving fruit quality.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe findings highlight the potential of GABA as a climate-resilient biostimulant for improving productivity, fruit quality and nutraceutical value in table grapes under subtropical conditions. GABA @50 mM resulted in highest TSS, lowest L* and maximum total anthocyanin content, whereas 100 mM was most effective in enhancing cluster morphological traits, including length, width and weight along with berry size, weight and overall yield. Improved colour parameters, characterized by higher a* and lower b* values further indicated enhanced berry pigmentation and marketable quality. In addition, it promoted the accumulation of bioactive compounds, reflected by increased TPC and enhanced activities of key ROS-scavenging enzymes (SOD, CAT and PAL), suggesting improved antioxidant potential through reduced H₂O₂ and MDA levels, better membrane stability and delayed senescence. Future prospects include integrating GABA into precision nutrient management and deficit irrigation strategies, elucidating its molecular regulation of anthocyanin biosynthesis and stress signaling pathways and validating its effectiveness through multi-location trials to develop standardized recommendations for sustainable viticulture.\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eGABA: \u0026gamma;-aminobutyric acid; CAT: Catalase; PAL: phenylalanine ammonia-lyase; SOD: superoxide dismutase; TCA: Tricarboxylic acid cycle; GAE: gallic acid equivalents; FCR: Folin\u0026ndash;Ciocalteu reagent\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u0026nbsp;\u003c/strong\u003eThe authors are thankful to Punjab Agricultural University, Ludhiana, India for providing the necessary research facilities\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatements and Declarations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest\u003c/strong\u003e The authors declare that they have no conflict of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contricutions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eKhushi Kumari:\u003c/strong\u003e Writing \u0026ndash; original draft, Investigation, Formal analysis, Data curation. \u003cstrong\u003eRachna Arora:\u003c/strong\u003e Writing \u0026ndash; review \u0026amp; editing, Conceptualization. \u003cstrong\u003eNaresh Kumar Arora:\u0026nbsp;\u003c/strong\u003eResources.\u003cstrong\u003e\u0026nbsp;Shalini Jhanji:\u003c/strong\u003e Methodology, Conceptualization\u003cstrong\u003e\u0026nbsp;Jaswinder Singh Brar:\u003c/strong\u003e Resources.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eUnusan N (2020) Proanthocyanidins in grape seeds: An updated review of their health benefits and potential uses in the food industry. 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J Plant Prod. 10(2):101-05.\u003c/li\u003e\n\u003cli\u003eHayat F, Khan U, Li J, Ahmed N, Khanum F, Iqbal S and Shahid M A (2023) \u0026gamma; Aminobutyric acid (GABA): a key player in alleviating abiotic stress resistance in horticultural crops: current insights and future directions. Horticulturae. 9(6):647. https://doi.org/10.3390/horticulturae9060647\u003c/li\u003e\n\u003cli\u003eAllahveran Oosalo A, Naseri L, Alirezalu A, Darvishzadeh R and Nejad Ebrahimi S (2023) The effect of gamma aminobutyric acid (GABA) foliar application on some biochemical characteristics and expression pattern of PAL and CHS genes in Qızıl Uzum grape (\u003cem\u003eVitis vinifera\u003c/em\u003e L.). J Plant Prod Res. 30(1):125-48. 10.22069/JOPP.2022.20280.2938\u003c/li\u003e\n\u003cli\u003eLorente-Mento J M, Guill\u0026eacute;n F, Mart\u0026iacute;nez-Romero D, Carri\u0026oacute;n-Antoli A, Valero D and Serrano M (2023) \u0026gamma;-Aminobutyric acid treatments of pomegranate trees increase crop yield and fruit quality at harvest. Sci Hortic. 309:111633. https://doi.org/10.1016/j.scienta.2022.111633\u003c/li\u003e\n\u003cli\u003eSoukht Saraei N, Varasteh F and Sadeghipour H R (2024) The effect of foliar application of gamma aminobutyric acid (GABA) and forchlorfenuron (CPPU) on some physiological and biochemical characteristics of strawberry \u003cem\u003ecv.\u003c/em\u003e Camarosa. Plant Prod. 48(3):363-81. https://doi.org/10.22055/ppd.2024.47877.2199\u003c/li\u003e\n\u003cli\u003eZhang Y, Lin B, Tang G, Chen Y, Deng M, Lin Y et al (2024) Application of \u0026gamma;-aminobutyric acid improves the postharvest marketability of strawberry by maintaining fruit quality and enhancing antioxidant system. Food Chemistry. 21:101252. https://doi.org/10.1016/j.fochx.2024.101252\u003c/li\u003e\n\u003cli\u003eCarri\u0026oacute;n-Antol\u0026iacute; A, Badiche-El Hilali F, Lorente-Mento J M, D\u0026iacute;az-Mula H M, Serrano M and Valero D (2023) Antioxidant Systems and Quality in Sweet Cherries Are Improved by Preharvest GABA Treatments Leading to Delay Postharvest Senescence. Int J Mol Sci. 25(1):260. https://doi.org/10.3390/ijms25010260\u003c/li\u003e\n\u003cli\u003eSuehiro Y, Mochida K, Tsuma M, Yasuda Y, Itamura H and Esumi T (2019) Effects of gibberellic acid/cytokinin treatments on berry development and maturation in the yellow-green skinned \u0026lsquo;Shine Muscat\u0026rsquo; grape. The Horticulture Journal. 88(2):202-13. https://doi.org/10.2503/hortj.UTD-04\u003c/li\u003e\n\u003cli\u003eMarco A T, Neto F J D, Junior A P, Da Silva M J R, Roberto S R and Smarsi R C (2017) Improvement of colour and increase in anthocyanin content of Niagara Rosada grapes with application of abscisic acid. Afr J Biotechnol. 16(25):1400-03. https://doi.org/10.5897/AJB2017.16073\u003c/li\u003e\n\u003cli\u003eKuhn N, Guan L, Dai Z W, Wu B H, Lauvergeat V, Gom\u0026egrave;s E et al. (2014) Berry ripening: Recently heard through the grapevine. J Exp Bot. 65(16):4543-59. https://doi.org/10.1093/jxb/ert395\u003c/li\u003e\n\u003cli\u003eFan Z, Lin B, Lin H, Lin M, Chen J and Lin Y (2022) \u0026gamma;-Aminobutyric acid treatment reduces chilling injury and improves quality maintenance of cold-stored Chinese olive fruit. Food Chemistry. 13:100208. https://doi.org/10.1016/j.fochx.2022.100208\u003c/li\u003e\n\u003cli\u003eBellincontro A, Fardelli A, De Santis D, Botondi R and Mencarelli F (2006) Postharvest ethylene and 1-MCP treatments both affect phenols, anthocyanins, and aromatic quality of Aleatico grapes and wine. Aust J Grape Wine Res. 12(2):141-49. https://doi.org/10.1111/j.1755-0238.2006.tb00054.x\u003c/li\u003e\n\u003cli\u003eMa Y, Wang P, Wang M, Sun M, Gu Z and Yang R (2019) GABA mediates phenolic compounds accumulation and the antioxidant system enhancement in germinated hulless barley under NaCl stress. Food Chem. 270:593-601. https://doi.org/10.1016/j.foodchem.2018.07.092\u003c/li\u003e\n\u003cli\u003eAli S, Anjum M A, Nawaz A, Ejaz S, Anwar R, Khaliq G et al. (2022) Postharvest \u0026gamma;-aminobutyric acid application mitigates chilling injury of aonla (\u003cem\u003eEmblica officinalis\u003c/em\u003e Gaertn.) fruit during low temperature storage. Postharvest Biol Technol. 185:111803. https://doi.org/10.1016/j.postharvbio.2021.111803\u003c/li\u003e\n\u003cli\u003eNgaffo Mekontso F, Duan W, Cisse E H M, Chen T and Xu X (2021) Alleviation of postharvest chilling injury of carambola fruit by \u0026gamma;-aminobutyric acid: physiological, biochemical, and structural characterization. Frontiers in Nutrition. 8:752583. https://doi.org/10.3389/fnut.2021.752583\u003c/li\u003e\n\u003cli\u003eNiazi Z, Razavi F, Khademi O and Aghdam M S (2021) Exogenous application of hydrogen sulfide and \u0026gamma;-aminobutyric acid alleviates chilling injury and preserves quality of persimmon fruit (\u003cem\u003eDiospyros kaki\u003c/em\u003e, cv. Karaj) during cold storage. Sci Hortic\u003cem\u003e. \u003c/em\u003e285:110198. https://doi.org/10.1016/j.scienta.2021.110198\u003c/li\u003e\n\u003cli\u003eHabibi F, Ramezanian A, Rahemi M, Eshghi S, Guill\u0026acute;en F, Serrano M and Valero D (2019) Post-harvest treatments with \u0026gamma;-aminobutyric acid, methyl jasmonate, or methyl salicylate enhance chilling tolerance of blood orange fruit at prolonged cold storage. J Sci Food Agric. 99(14):6408-17. https://doi.org/10.1002/jsfa.9920\u003c/li\u003e\n\u003cli\u003eJin Y, Zhi L, Tang X, Chen Y, Hancock J and Hu X (2023) The function of GABA in plant cell growth, development and stress response. Phyton. 92(8):2211. 10.32604/phyton.2023.026595\u003c/li\u003e\n\u003cli\u003eSeifikalhor M, Aliniaeifard S, Hassani B, Niknam V and Lastochkina O (2019) Diverse role of \u0026gamma;-aminobutyric acid in dynamic plant cell responses. Plant Cell Rep. 38(8):847-67. https://doi.org/10.1007/s00299-019-02396-z\u003c/li\u003e\n\u003cli\u003eSingh R, Rastogi S and Dwivedi U N (2010) Phenylpropanoid Metabolism in Ripening Fruits. Compr Rev Food Sci Food Saf. 9(4):398-416. https://doi.org/10.1111/j.1541-4337.2010.00116.x\u003c/li\u003e\n\u003cli\u003eKhaliq G, Ali S, Ejaz S, Abdi G, Faqir Y, Ma J and Ali A (2023) \u0026gamma;-Aminobutyric acid is involved in overlapping pathways against chilling injury by modulating glutamate decarboxylase and defense responses in papaya fruit. Front Plant Sci. 14:1233477. https://doi.org/10.3389/fpls.2023.1233477\u003c/li\u003e\n\u003cli\u003eAli M A, Ayvaz Sonmez D and Kafkas E (2025) Enhancement of Antioxidant Defense Mechanism by Preharvest Gaba Spray on Postharvest Quality of Strawberries. Horticulturae. 11:170-84.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1. Effect of GABA on berry length (mm), diameter (mm) and weight (g) of grape \u003cem\u003ecv.\u0026nbsp;\u003c/em\u003eFlame Seedless\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTreatment\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 26px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBerry length (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 24px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBerry diameter (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 26px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBerry weight (g)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e2024\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e2025\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e2024\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e2025\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e2024\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e2025\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003eT1 (GABA @25 mM)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e17.13\u0026plusmn;0.9b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e17.48\u0026plusmn;0.9bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e16.38\u0026plusmn;0.2b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e16.89\u0026plusmn;0.3b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e2.79\u0026plusmn;0.04b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e2.84\u0026plusmn;0.19bc\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003eT2 (GABA @50 mM)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e18.46\u0026plusmn;0.2ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e18.81\u0026plusmn;0.3ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e17.91\u0026plusmn;0.3a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e18.14\u0026plusmn;0.3a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e2.88\u0026plusmn;0.04ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e3.03\u0026plusmn;0.05ab\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003eT3 (GABA @100 mM)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e18.96\u0026plusmn;0.5a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e19.76\u0026plusmn;0.7a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e18.43\u0026plusmn;0.4a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e18.75\u0026plusmn;0.3a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e2.99\u0026plusmn;0.04a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e3.18\u0026plusmn;0.06a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003eT4 (Control)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e14.99\u0026plusmn;0.4c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e15.76\u0026plusmn;0.4c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e14.82\u0026plusmn;0.2c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e14.95\u0026plusmn;0.3c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e2.51\u0026plusmn;0.03c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e2.68\u0026plusmn;0.04c\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003eLSD (p\u0026lt; 0.05)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e1.76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e1.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e0.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e0.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e0.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e0.34\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2. Effect of GABA on\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003efruit colour index (L*, a* and b*)\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;of grape \u003cem\u003ecv.\u0026nbsp;\u003c/em\u003eFlame Seedless\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 23px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTreatment\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL*\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ea*\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 26px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eb*\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e2024\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e2025\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e2024\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e2025\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e2024\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e2025\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 23px;\"\u003e\n \u003cp\u003eT1 (GABA @25 mM)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e40.22\u0026plusmn;0.6b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e39.09\u0026plusmn;0.9b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e12.96\u0026plusmn;0.2c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e13.54\u0026plusmn;0.2b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e13.17\u0026plusmn;0.3ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e13.04\u0026plusmn;0.6b\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 23px;\"\u003e\n \u003cp\u003eT2 (GABA @50 mM)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e35.54\u0026plusmn;0.4d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e34.32\u0026plusmn;0.5c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e14.19\u0026plusmn;0.2b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e14.88\u0026plusmn;0.2a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e12.11\u0026plusmn;0.4bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e11.91\u0026plusmn;0.2c\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 23px;\"\u003e\n \u003cp\u003eT3 (GABA @100 mM)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e37.99\u0026plusmn;0.5c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e37.61\u0026plusmn;0.5b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e15.36\u0026plusmn;0.3a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e15.91\u0026plusmn;0.4a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e11.54\u0026plusmn;0.1c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e11.17\u0026plusmn;0.3c\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 23px;\"\u003e\n \u003cp\u003eT4 (Control)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e44.36\u0026plusmn;0.3a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e43.6\u0026plusmn;1.2a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e11.46\u0026plusmn;0.4d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e10.07\u0026plusmn;0.5c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e13.70\u0026plusmn;0.5a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e14.22\u0026plusmn;0.2b\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 23px;\"\u003e\n \u003cp\u003eLSD (p\u0026lt;.05)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e1.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e1.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e0.86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e0.86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e1.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e1.08\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3. Effect of GABA on cluster length (cm), width (cm) and weight (g) of grape \u003cem\u003ecv.\u0026nbsp;\u003c/em\u003eFlame Seedless\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" align=\"left\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 23px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTreatment\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCluster length (cm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCluster width (cm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 26px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCluster weight (g)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e2024\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e2025\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e2024\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e2025\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e2024\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e2025\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 23px;\"\u003e\n \u003cp\u003eT1 (GABA @25 mM)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e18.08\u0026plusmn;0.2b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e20.27\u0026plusmn;0.3b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e16.1\u0026plusmn;0.3b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e17.24\u0026plusmn;0.5b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e340.67\u0026plusmn;7.7b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e348.78\u0026plusmn;3.8b\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 23px;\"\u003e\n \u003cp\u003eT2 (GABA @50 mM)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e19.96\u0026plusmn;0.3a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e21.16\u0026plusmn;0.4ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e17.31\u0026plusmn;0.3b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e18.13\u0026plusmn;0.2ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e357.8\u0026plusmn;4.0a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e361.67\u0026plusmn;4.2a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 23px;\"\u003e\n \u003cp\u003eT3 (GABA @100 mM)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e21.38\u0026plusmn;0.8a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e22.33\u0026plusmn;0.7a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e18.68\u0026plusmn;0.2a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e18.95\u0026plusmn;0.3a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e366.87\u0026plusmn;4.0a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e370.37\u0026plusmn;4.7a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 23px;\"\u003e\n \u003cp\u003eT4 (Control)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e15.66\u0026plusmn;0.7c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e16.99\u0026plusmn;0.8c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e14.58\u0026plusmn;0.7c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e15.24\u0026plusmn;0.3c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e316.57\u0026plusmn;2.8c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e320.15\u0026plusmn;2.7c\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 23px;\"\u003e\n \u003cp\u003eLSD (p\u0026lt;.05)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e1.73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e1.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e1.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e1.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e15.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e12.02\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":false,"email":"","identity":"applied-fruit-science","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Applied Fruit Science","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"VoR Journals","inReviewEnabled":false,"inReviewRevisionsEnabled":false},"keywords":"anthocyanins, antioxidants, phenolics, fruit colour, Flame Seedless","lastPublishedDoi":"10.21203/rs.3.rs-9036075/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9036075/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe grapevine (\u003cem\u003eVitis vinifera\u003c/em\u003e L.) stands as one of the most important fruit crops due to its high nutritional value, palatability and economic significance. In order to mitigate the harmful effects of climate change on fruit quality, primarily the berry colouration and antioxidant potential, the present study was conducted to investigate the potential of foliar application of γ-aminobutyric acid (GABA) during two consecutive cropping seasons on grape cv. Flame Seedless. At the onset of veraison, 17-year-old vines were sprayed with GABA @ 25, 50 and 100 mM. The results revealed that GABA @100 mM significantly improved total phenolic content and antioxidants, remaining statistically comparable with GABA @50 mM. Fruit colour was also favourably influenced, as it produced higher a* and lower b* values, improving berry appearance. Moreover, it also improved the cluster and berry physical traits by recording the highest cluster length, width and weight, along with increased berry size, berry weight and yield. Antioxidant enzymes, including catalase (CAT), phenylalanine ammonia-lyase (PAL) and superoxide dismutase (SOD), were significantly elevated under all treatments, with 50 and 100 mM concentrations exhibiting the strongest responses. GABA @50 mM recorded the highest TSS, lowest L* values and maximum total anthocyanin content, followed closely by 100 mM. Overall, pre-harvest foliar GABA @ 50\u0026ndash;100 mM offers great potential to enhance grape productivity, quality, adaptability, precision nutrient use, deficit irrigation efficiency, eco-friendly cultivation and premium export.\u003c/p\u003e","manuscriptTitle":"Elevating Berry Excellence: GABA-Induced Stimulation of Anthocyanin Biosynthesis and Antioxidant Defense in Flame Seedless Grapes","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-12 13:31:04","doi":"10.21203/rs.3.rs-9036075/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-16T06:57:46+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-10T05:29:40+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-26T16:08:51+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"77999372947113757471490780138173902226","date":"2026-03-21T09:14:30+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"41636155971065937281234779718443685228","date":"2026-03-19T11:09:28+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-09T08:33:53+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-05T07:08:08+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-05T07:02:41+00:00","index":"","fulltext":""},{"type":"submitted","content":"Applied Fruit Science","date":"2026-03-05T05:05:03+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":false,"email":"","identity":"applied-fruit-science","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Applied Fruit Science","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"VoR Journals","inReviewEnabled":false,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"e19a1acd-aaf1-4198-83f2-d5d2e2fdf51a","owner":[],"postedDate":"March 12th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-07T07:25:16+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-12 13:31:04","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9036075","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9036075","identity":"rs-9036075","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}