Functional characterization of chalcone isomerase gene HvCHI revealing its role in anthocyanin accumulation in Hosta ventricosa

Anthocyanins are natural colorants are synthesized in a branch of the flavonoid pathway. chalcone isomerase gene HvCHI catalyzes the conversion of chalcones to flavanones which is a key regulatory enzyme of anthocyanin biosynthesis in plants. Hosta ventricosa is an ornamental plant with elegant flowers and rich colorful leaves. How the function of HvCHI contributes to the anthocyanins biosynthesis is still unknown. In this study, the CHI homolog was identified from H. ventricosa and sequence analysis showed that HvCHI possessed the conserved substrate binding and catalytic domains. A phylogenetic analysis showed HvCHI had a strong sister relationship with Dracaena cambodiana CHI. Gene expression analysis revealed that HvCHI was constitutive expressed in all tissues and expressed highly in flower as well as was positively correlated with anthocyanin content. In addition, the subcellular location of HvCHI showed that is in cytoplasm. Overexpression of HvCHI in transgenic tobacco lines enhanced the anthocyanins accumulation along with the key genes upregulated, such as NtF3H , NtF3′H , NtF3′5′H , NtDFR , NtUFGT , and NtANS . Our results indicated a functional activity of the HvCHI , which provide an insight into the regulation of anthocyanins content in H. ventricosa.