Isolation and characterization of cinnamate 4-hydroxylase gene from cultivated ramie ( Boehmeria nivea )

The present study aimed to describe the cDNA cloning of the cinnamate 4-hydroxylase (C4H) gene from ramie, predict the protein sequence and perform phylogenetic and structural analyses of this gene. C4H catalyses the hydroxylation of trans-cinnamic acid to p-coumaric acid, which plays a crucial role in lignin biosynthesis. In the present study, the gene encoding C4H was cloned by polymerase chain reaction (PCR) technology from cultivated ramie (Boehmeria nivea) and named BnGC4H. In addition, bioinformatics and tissue expression analyses were performed. The results showed that the cloned BnGC4H cDNA contained a 1518-bp open reading frame encoding a 505–amino acid protein. The sequence of BnGC4H is available from the GenBank database with accession number KY937946. The amino acid sequence and structural analysis revealed that BnGC4H shared conserved domains with other C4H forms, including cytochrome P450 domain and trans-cinnamate 4-monooxygenase domain. The phylogenetic analysis indicated that BnGC4H was closely related to Aquilaria sinensis C4H and Ruta graveolens C4H. Real-time quantitative reverse transcription–PCR and RNA in situ hybridization showed that BnGC4H was strongly expressed in the xylem during the maturity stage. The findings provided a theoretical basis for further exploring the function of BnGC4H in the lignin biosynthesis and regulation in ramie.