Identification and expression analysis of phosphate transporter genes and metabolites in response to phosphate stress in Capsicum annuum

Till date, no systematic study of phosphate transporter (PHT) genes is reported in Capsicum species. For the first time, we report the identification and homology modelling of C. annuum PHT genes (CaPHT) belonging to CaPHT1, CaPHT2, CaPHT3, CaPHT4, CaPHT5 and CaPHO family. Further, gene duplication analysis identified 14 segmental and 5 tandemly duplicated gene pairs. Synteny analysis showed high collinearity of CaPHTs with tomato and potato. The 3D structures of CaPHT genes were highly similar to the reference model suggesting potential functional similarities of PHT genes in Capsicum. Analysis in fruit transcriptomes and validation using quantitative real-time PCR showed differential expressions (DE) of CaPHTs in leaf, stem, root, flower and fruit tissues of C. annuum. During P-stress conditions CaPHT1;3 to CaPHT1;7, CaPHT3;1 to CaPHT3;4 and six members of CaPHO family showed DE patterns between leaf and root tissues. Metabolite profiling of plants grown under P-stress conditions showed significantly (p-value <0.001) higher content of glucose, fructose and erythritol in leaves compared to roots. Furthermore, it was observed that most of the organic acids content in leaf decreased under P-stress. The identified CaPHTs would serve as a resource for further studies of phosphate uptake and homeostasis in Capsicum.