Chlorogenic acid accumulation and related gene expression in peach fruit

To reveal the molecular mechanism in the accumulation of chlorogenic acids (CGAs) in peach ( Prunus persica ) fruit during growth and development, CGA contents in the flesh of the three peach cultivars ‘Ruiguang 18’, ‘Heiyoutao’, and ‘Beijingyixianhong’ were determined. The expression levels of CGA metabolism-related genes were analyzed based on transcriptome data (RNA-seq). These candidate genes were then screened and real-time fluorescent quantitative PCR (qRT-PCR) was performed to verify their expression. The results showed that the content of total CGAs, 5- O -caffeoylquinic acid and 3- O -caffeoylquinic acid, in the flesh of ‘Ruiguang 18’ exhibited a decreasing trend during fruit development, and there was a great drop at maturity stage ( P < 0.05). The three contents in ‘Heiyoutao’ increased first at stage S2 ( P < 0.05) and then decreased significantly ( P < 0.05). In ‘Beijingyixianhong’, they stayed stable in the early stages, then total CGAs and 3- O -caffeoylquinic acid decreased significantly at the maturity stage ( P < 0.05). RNA-seq transcriptome data analysis and qRT-PCR expression analysis showed that the accumulation of CGAs in fruit flesh was mainly affected by the expression of Prupe.3G100800 ( PpHCT ) and Prupe.3G107300 ( Pp4CL ), and their expression levels were highly consistent with total CGA content. Thus, we concluded that Prupe.3G100800 ( PpHCT ) and Prupe.3G107300 ( Pp4CL ) are the key genes for CGAs synthesis in peach flesh.