Expression of the Chalcone Synthase Gene in Scutellaria baicalensis Hairy Root Cultures Was Unusually Reduced by Environmental Stresses

Abstract

A cDNA clone, named as SbCHS cDNA, encoding chalcone synthase (CHS, EC 2.3.1.74) was isolated from a cDNA library derived from hairy root cultures of Scutellaria baicalensis Georgi by screening with a 1.4 kbp full length CHS cDNA of Phaseolus vulgaris as the probe. Complete nucleotide sequence of the SbCHS cDNA contained 1170-base pair open reading frame encoding 390 amino acid residues. The deduced amino acid sequence of SbCHS cDNA exhibited 82.1% identity with CHS of P. vulgaris. SbCHS mRNA expression in S. baicalensis hairy roots was unusually reduced by UV light irradiation, wounding, and yeast extract, as shown by Northern blot analysis. Greater formation of naringenin chalcone (100%) than of pinocembrin chalcone (67.4%) was observed by using thin-layer chromatography (TLC) to assess the enzymatic activity of recombinant SbCHS expressed in Escherichia coli.