Characterization of the gene encoding 4-coumarate:CoA ligase in Coleus forskohlii

4-coumarate:coenzyme A ligase (4CL) converts 4-coumaric acid and its hydroxylated derivatives into the CoA thiol esters, directing carbon flux into various end-products of phenylpropanoid metabolism, such as flavonoids and lignins. In this study, full-length cDNA showing homology with plant 4CL genes was cloned from Coleus forskohlii and was designated as Cf4CL (Accession No. KF643242). Cf4CL was found to contain an ORF of 1626 bps. The computational translation of Cf4CL encoded a protein of 541 amino acids. Theoretical isoelectric point and molecular weight of Cf4CL were calculated to be 5.55 and 58.65kDa, respectively. Phylogenetic tree clustered Cf4CL with the class I 4CLs (involved in lignin biosynthesis). Spatial distribution of Cf4CL in different tissues and its expression in response to various stresses was carried out through qPCR. Abscisic acid (ABA) treatment strongly induced the expression of Cf4CL. Homology modeling and docking studies further ascertain the role of Cf4CL gene in lignin biosynthesis. In silico prediction suggested that Cf4CL may be post-transcriptionally regulated by microRNAs. Decreased expression of miR1886 in response to ABA treatment was associated with an increase in Cf4CL transcripts and lignin content, thus suggesting a possible role of miR1886 in regulating lignin biosynthesis in C. forskohlii.