Anthocyanin Content in the Capsicum Species Fruits Correlates with Expression Levels of Flavonoid Pathway Structural and Regulatory Genes

Abstract

In fruits of cultivars of pepper species Capsicum annuum (Sirenevyi Cub), C. frutescens (Samotsvet) and C. chinense (Pimenta da Neyde), which differ in the pigmentation profile during maturation, the content of anthocyanins and the expression pattern of the structural and regulatory genes of anthocyanin biosynthesis were determined. Anthocyanins were found in the fruit of the Sirenevyi Cub cultivar as well as in the peel and pulp of Samotsvet and Pimenta da Neyde cultivars. In the peel of the fruits of all three analyzed cultivars, the levels of expression of structural genes for the biosynthesis of anthocyanins are two or more times higher than in the pulp. In cv. Samotsvet and Pimenta da Neyde, the expression in the pulp of CHS, F35H, DFR, ANS, and UFGT are higher than that of cv. Sirenevyi Cub. The cv. Pimenta da Neyde is characterized by a high expression of structural genes in the pulp and peel of ripe fruit. Expression of transcription factor genes anthocyanin2 (R2R3-MYB) and MYC (bHLH) was detected in the peel of fruits of cv. Sirenevyi Cub as well as in the peel and pulp of fruits of cv. Samotsvet and Pimenta da Neyde at all the analyzed stages of ripening. For all structural genes of the anthocyanin biosynthesis pathway, a high correlation was found (r = 0.54‒0.93) between the expression levels of all anthocyanin biosynthesis structural genes and anthocyanin content in fruits. High correlation (r = 0.88) is also shown for MYC. For the anthocyanin2, correlation (r = 0.85) is present only for cv. Sirenevyi Cub and Pimenta da Neyde but not for cv. Samotsvet.