Molecular cloning and expression profiling of a chalcone synthase gene from hairy root cultures of Scutellaria viscidula Bunge

Abstract

A cDNA encoding chalcone synthase (CHS), the key enzyme in flavonoid biosynthesis, was isolated from hairy root cultures of Scutellaria viscidula Bunge by rapid amplification of cDNA ends (RACE). The full-length cDNA of S. viscidula CHS, designated as Svchs (GenBank accession no. EU386767), was 1649 bp with a 1170 bp open reading frame (ORF) that corresponded to a deduced protein of 390 amino acid residues, a calculated molecular mass of 42.56 kDa and a theoretical isoelectric point (pI) of 5.79. Multiple sequence alignments showed that SvCHS shared high homology with CHS from other plants. Functional analysis in silico indicated that SvCHS was a hydrophilic protein most likely associated with intermediate metabolism. The active sites of the malonyl-CoA binding motif, coumaroyl pocket and cyclization pocket in CHS of Medicago sativa were also found in SvCHS. Molecular modeling indicated that the secondary structure of SvCHS contained mainly α-helixes and random coils. Phylogenetic analysis showed that SvCHS was most closely related to CHS from Scutellaria baicalensis. In agreement with its function as an elicitor-responsive gene, the expression of Svchs was induced and coordinated by methyl jasmonate. To our knowledge, this is the first report to describe the isolation and expression of a gene from S. viscidula.

A specialized flavone biosynthetic pathway has evolved in the medicinal plant, Scutellaria baicalensis

“…vestidula , SvCHS (ACC68839.1), a close relative of S . baicalensis that also makes RSFs ( 44 ). However, SbCHS-2 has only 83% identity with the SbCHS-1 gene highly expressed in flowers of S .…”

Molecular and functional characterization of two isoforms of chalcone synthase and their expression analysis in relation to flavonoid constituents in Grewia asiatica L

“…Some extensively studied CHS genes include those from Oryza sativa , Medicago sativa , Zea mays and Rehumemodi [11,16]. These genes are predominantly expressed in flowers and at different developmental stages [12,17,18,19].…”

Deep Sequencing of the Scutellaria baicalensis Georgi Transcriptome Reveals Flavonoid Biosynthetic Profiling and Organ-Specific Gene Expression

“…The known enzymes for these transformation are: naringenin 3-dioxygenase (K00475, F3H), flavonol synthase (K05278, FLS)[ 15 ], trans-cinnamate 4-monooxygenase (K00487, CYP73A)[ 16 ], Polyketide reductase (K08243, PKR)[ 17 ], flavonoid 3'-monooxygenase (K05280, E1.14.13.21)[ 18 ], leucoanthocyanidin dioxygenase (K05277, E1.14.11.19), anthocyanidin reductase (K08695, ANR)[ 19 ], leucoanthocyanidin reductase (K13081, LAR)[ 20 ], shikimate O-hydroxycinnamoyltransferase (K13065, HCT)[ 21 ], coumaroylquinate (coumaroylshikimate) 3'-monooxygenase (K09754, C3'H)[ 22 ], flavanone 4-reductase (K13082, DFR)[ 23 ], caffeoyl-CoA O-methyltransferase (K00588, E2.1.1.104), flavonoid 3',5'-hydroxylase (K13083, CYP75A)[ 24 ], et al The chalcone synthase (CHS) has been isolated from hairy root cultures of S . viscidula by rapid amplification of cDNA ends (RACE)[ 25 ]. And, the levels of flavone can be enhanced through overexpression of chalcone isomerase in hairy root cultures of S .…”