Differential Expression Analysis of Genes Related to Flesh Color in Hylocereu polyrhizus and Hylocereu undatus

Abstract

Pitaya is a burgeoningly tropical fruit, there are two common varieties, red peel with red pulp and red peel with white pulp. To investigate the reason of different colors in two kinds of pitaya, explore differencially expressed genes (DEGs), in this study, we profiled transcriptome in flesh of two varieties (Hylocereu polyrhizus and Hylocereu undatus) in green stage and mature stage respectively. 53 240 reads with high quality were obtained. Analysing the DEGs, we found there were bigger differences in different stage rather than different variety. Gene ontology (GO) functional analysis and KEGG pathway analysis were adopted in R1 VS R3 and W3 VS W3. Through GO analysis, we found many genes enriched in protein binding transcription factor activity in molecule founction. Through KEGG pathway analysis, we found most genes were enriched in biosynthesis of secondary metabolism, amino acid and nucleic acid metabolism, and tyrosine metabolism. In addintion, tyrosine was the precursor of betalaines. In conclusion, the development of Hylocereu polyrhizus accompanying by the synthesis of a large amount of betalaines, tyrosine played a key role as a precursor, and the synthesis of this pigment required a mass of amino acids, enzymes, and transcription factors. Betalaines synthesis pathway has not cleared yet, this study explored key genes related to betalaines synthesis and provided useful information for optimizing the betalaines synthesis pathway, which was the basis of later experiments.