Functional analysis of 4-coumarate: CoA ligase from Dryopteris fragrans in transgenic tobacco enhances lignin and flavonoids

4-Coumaric acid: coenzyme A ligase (4CL) is a key enzyme in the phenylpropanoid metabolic pathway that regulates the biosynthesis of lignin and flavonoids. Therefore, the study of 4CL is important to explore the accumulation and regulation of metabolites. This study investigated the role that the 4CL2 gene from Dryopteris fragrans (Df4CL2) plays in the metabolite synthesis. Changes in gene expression, enzyme activity, and the content of lignin and flavonoids were measured in different tissues of tobacco as model plant that was successfully transferred with Df4CL2. Tobacco plants with Df4CL2 (transgenic tobacco, TT) were successfully obtained via the Agrobacterium-transformation method. This TT tended to be thicker and had an earlier flowering period than wild type tobacco (WT). The expression levels of Df4CL2 were higher in the stem, leaf, and root in TT compared to WT. In addition, compared to WT, TT had higher 4CL enzyme activity and higher lignin and flavonoids contents. This suggests that Df4CL2 is involved in the synthesis of lignin and flavonoids in D. fragrans. This research provides important evidence toward understanding the phenylpropanoid metabolic pathway in ferns.