Genome-wide analysis of chalcone synthase (CHS) family from eggplant (Solanum melongena L.) in flavonoid biosynthetic pathway and expression pattern in response to heat stress

Abstract

Enzymes of chalcone synthase (CHS) family participate in the synthesis of a series of secondary metabolites in plants, fungi and bacteria. CHS showed significant correlation to the accumulation patterns of anthocyanin. The peel color mainly determined by the content of anthocyanin, is a majority economic trait for eggplant affected by heat stress. A total of 7 CHS(SmCHS1-7) putative genes were identified in genome-wide of eggplant (S. melongena L.). The SmCHS genes distribute on 7 scaffolds and were classified into 3 clusters. Phylogenetic relationships analysis showed that 73 CHS genes from 7 Solanaceae species were classified into 10 groups. SmCHS5, SmCHS6 and SmCHS7 were continuously down-regulated under 38{degrees}C and 45{degrees}C treatment, while SmCHS4 was up-regulated under 38{degrees}C but little change at 45{degrees}C in peel. Expression profiles of anthocyanin biosynthesis key genes families showed that the PAL, 4CL and AN11 genes were mainly expressed in all five tissues. CHI, F3H, F35H, DFR, 3GT and bHLH1 genes were expressed in flower and peel. Under heat stress, 52 key genes expression level were reduced under heat stress. By contrast, expression patterns of eight key genes similar to SmCHS4 up-regulated at the 38{degrees}C-3h. Comparative analysis of putative CHS protein biochemical characteristics, cis-regulatory elements, regulatory network revealed that SmCHS genes family have conservation gene structure and functional diversification. SmCHS showed two or more expression patterns and execute multiple functions to regulate anthocyanin content. Combined with regulatory networks, it is possible to further understand the regulation mechanism of peel color in eggplant.