Identification, characterization and expression analysis of the 4-coumarate-coA ligase gene family in Bletilla striata

The 4-coumarate-coA ligase (4CL) gene plays an important role in plant growth and development as well as the synthesis of secondary metabolites, but its function in Bletilla striata has not been extensively studied. Based on the former full-length transcriptome sequencing database built on suspension culture cells of B. striata (Bletilla striata), we identified 4CL gene family members and conducted secondary structure, motif, evolutionary tree, and KEGG enrichment analysis of their proteins using bioinformatics software. We also analyzed their genetic polymorphisms and expression patterns using EST-SSR and qPCR. We have confirmed the relationship between the expression of the 4CL gene and the biosynthesis of secondary metabolites in B. striata through correlation analysis. Our results indicate that 21 4CL genes were obtained from the transcriptome database, named as Bs4CL (4-coumarate-coa ligase of Bletilla striata) 1–21 gene. They were subcellularly located in peroxisome, and the secondary structure was mainly comprised of random coil and alpha helix. KEGG enrichment analysis showed that Bs4CL gene family members were mainly involved in lipid metabolism, alpha-linoleic metabolism, amino acid metabolism, phenylpropanoid biosynthesis, and other secondary metabolites. According to EST-SSR detection, we found that Bs4CL genes showed genetic polymorphism in local varieties of B. striata. q-PCR analysis showed that the expression of Bs4CL genes was tissue-specific in different tissue. Through the correlation analysis, we found that these genes play important roles in the synthesis of Coelonin, Dactylorhin A, and Militarine. These results indicate that Bs4CL gene family is involved in growth development and biosynthesis of secondary metabolites in B. striata.