Molecular cloning and characterization of cDNAs encoding cinnamoyl CoA reductase (CCR) from barley (Hordeum vulgare) and potato (Solanum tuberosum).

Cinnamoyl CoA reductase catalyzes the reduction of cinnamic acid CoA esters into their corresponding aldehydes, the first step of the phenylpropanoid pathway specifically dedicated to monolignol biosynthesis. Two cDNA clones encoding cinnamoyl CoA reductase (CCR) have been isolated from Hordeum vulgare (HvCCR) and Solanum tuberosum (StCCR1). Amino acid sequence alignment revealed the motif, NWYCY, representing the active site of CCR, conserved in both the encoded HvCCR and StCCR1 amino acid sequences. The HvCCR encoded protein possesses substantial homology with CCRs isolated and cloned form other sources; the highest identity (89%) was observed with CCR from fescue (Festuca arundicinea). Expression analysis by RT-PCR demonstrated that the HvCCR gene is expressed in barley stem and root tissue while no expression is detected in leaves and flowers. This expression pattern suggests that HvCCR is involved in constitutive lignification. Transcripts of StCCR1 were detected in potato root, leaf and also in stem although at a very low level.