Abstract:Anthocyanidins belong to a class of biosynthetic metabolites of flavonoids in higher plants. Chalcone isomerase (CHI) catalyzes the conversion of naringenin chalcone into flavanone. Chi-a gene was cloned from Petunia hybrida Vilm. The sequence of the coding region was 726 bp, encoding a protein of 241 amino acids and was expressed in E. coli. The amino acid sequence homology was compared with CHI from a variety with plant species.