The soybean cinnamate 4-hydroxylase gene GmC4H1 contributes positively to plant defense via increasing lignin content

Lignification is a key event in plant defense against pathogens. In the plant lignin biosynthetic pathway, cinnamate 4-hydroxylase (C4H) catalyzes the conversion of trans-cinnamic acid to p-coumaric acid. However, the potential role of C4H in plant defense remains elusive. In this research, a soybean C4H gene, GmC4H1, was identified via microarray-based comparative transcriptome analysis of genes responsive to Phytophthora sojae infection. The accumulation of GmC4H1 transcripts increased significantly upon P. sojae infection. Nicotiana benthamiana plants overexpressing GmC4H1 demonstrated enhanced lignin accumulation and elevated resistance to both Phytophthora parasitica and Verticillium dahliae. The silencing of GmC4H1 in soybean hairy roots resulted in decreased resistance to P. sojae. These results together suggest that GmC4H1 contributes positively to plant defense against various pathogens, possibly by enhancing lignin biosynthesis.