Transcriptomic analysis of pepper roots (Capsicum annuum) under phosphorus deficiency

Abstract Background: Phosphorus (P) is an important nutritional element needed by plants. Roots obtain P as inorganic phosphate (Pi), mostly in H2PO-4 form. It is vital to plants a sufficient supply of Pi since it participates in important processes like photosynthesis, energy transfer, protein activation, amongst others. The physicochemical properties and the adsorption of Pi to organic material usually makes the bioavailability in soil low causing that crops and undomesticated plants experience variations in accessibility or even a persistent phosphate limitation. There is little information on the influence of Pi availability in an important economic crop such as pepper. Methods and results: In this study, transcriptome data from pepper roots under low-Pi stress was analyzed in order to identify Pi starvation-responsive genes and their relationship with metabolic pathways and functions. An overall of 62 differentially expressed genes (DEGs) were identified; gene ontology analysis showed DEGs classification into 48 functional categories demonstrating the diversity of genes responding to the stress. The most relevant down regulated DEGs were related to rhythmic process, catalytic activity, and cellular anatomical entity; whereas the up-regulated DEGs were associated to cellular process, biological regulation, metabolic process and response to stimulus categories. KEGG enrichment revealed that metabolic pathways such as porphyrin and chlorophyll metabolism was down-regulated, and galactose metabolism and fatty acid metabolism were up-regulated. Conclusion: Present results indicate that bell pepper follows diverse processes related to low Pi tolerance regulation, such as remobilization of internal Pi, alternative metabolic pathways to generate energy and regulators of root development.