Dependence of Pepper Fruit Colour on Basic Pigments Ratio and Expression Pattern of Carotenoid and Anthocyanin Biosynthesis Genes

Abstract

Fruit biochemical analysis of four pepper (Capsicum annuum L.) cultivars, contrasting in immature and ripe fruit colour, was performed, and chlorophylls, carotenoids and anthocyanins were profiled in the peel and pulp during fruit ripening. It was found that pericarp parts (peel and pulp) differ in pigment composition and accumulation mode. In the same fruit tissues, the expression pattern of structural genes of the carotenoid (PSY1, PSY2, LCYb, and CCS) and anthocyanin (CHS, F3 '5 'H, DFR, ANS, and UFGT) pathways was evaluated. It was shown that carotenoid content positively correlates with the PSY1, LCYb and CCS expression level in the fruit pulp and with CCS expression level in the fruit peel. In pepper cultivars with purple-coloured immature fruits (Sirenevyj cub, Otello), a positive correlation was shown between the CHS, F3 '5 'H, DFR, ANS, and UFGT expression levels and the anthocyanin content in the peel. Thus, it was shown that in the pepper fruit, peel and pulp colours are regulated independently and determined by the main pigment ratio and the activity of carotenoid and anthocyanin biosynthesis genes.