Overexpression of chalcone synthase gene improves flavonoid accumulation and drought tolerance in tobacco

Abstract

Background: Flavonoids are important secondary metabolites in plants that play important roles in maintaining the cellular redox balance of cells. Chalcone synthase (CHS) is the key enzyme in the flavonoid biosynthesis pathway and has been found to monitor changes due to drought stress tolerance.Results: In this study, a CHS gene in tobacco (Nicotiana tabacum) was overexpressed. Results revealed that transgenic tobacco plants were more tolerant than control plants to drought stress. Transcription levels of the key genes involved in the flavonoid pathway and the contents of seven flavonoids significantly increased in transgenic tobacco plants (p < 0.01). Overexpression of the CHS gene led to lower concentrations of the oxidative stress product, malondialdehyde (MDA). Additionally, 11 CHS family genes were mined from the tobacco genome. Based on the phylogenetic tree, these genes split into two groups with eight genes clustered together with the bona fide Arabidopsis CHS gene, suggesting that those tobacco genes are CHS genes. Further phylogenetic analyses indicated that the tobacco CHS genes grouped further into three independent clades with the cloned tobacco CHS gene located within Clade iii. The tobacco CHS family genes exhibited a highly conserved CDS length, pI, and molecular weight of the encoded peptides. All CHS peptides contained two conserved domains, and the genes harbored two or three exons.Conclusions: Based on the results of this study, the NtCHS gene is considered a possible candidate gene for genetically engineering enhanced drought tolerance and improved responses to oxidative stress in plants.