Analysis of Regulation Networks in the Formation of Green Pigment in Garlic

Abstract Background: Garlic (Allium sativum L.) has high medical and edible value, but is prone to producing green pigment during storage, which seriously affects product quality. Herein, we found multiple metabolic pathways involved in green pigment formation by analyzing the transcriptome and proteome changes of garlic stored at 4 °C for 0 day (DS0), 10 days (DS1), 15 days (DS2) and 40 days (DS3). Results: In this work, we found that porphobilinogen is a precursor of garlic green pigment and the citrate cycle (TCA cycle) can promote the formation of garlic green pigment by increasing the content of porphobilinogen. The salicylic acid (SA) inhibits garlic greening, whereas the lignin synthesis pathway positively correlates with greening. In addition to the above metabolic pathways, other pathways may be associated with the formation of garlic’s green pigment, such as glycolysis/gluconeogenesis, pyruvate metabolism and fatty acid metabolism. It has been reported that pyruvate and amino acids play a role in garlic greening, which were also demonstrated in this study. Conclusion: our results have important implications for understanding the mechanism of green pigment formation in garlic.