Cinnamoyl-CoA reductase 1 is involved in the lignin biosynthetic pathway. The enzyme catalyzes one of the last steps of monolignol biosynthesis, the conversion of cinnamoyl-CoAs into their corresponding cinnamaldehydes with the following reaction: (E)-cinnamaldehyde + NADP+ + CoA = (E)-cinnamoyl-CoA + NADPH + H+. Substrates for this enzyme include feruloyl-CoA, sinapoyl-CoA, caffeoyl-CoA and p-coumaroyl-CoA. When downregulated, mutants produce an increased pool of feruloyl-CoA that can be used for conversion to monolignol ferulate conjugates. In addition, the hydroxyphenyl units were observed to be strongly decreased and the syringyl/guaiacyl ratio was slightly increased. The decreased lignin content and monomers did not appear to impact the plant growth or biomass. The increase in monolignol conjugates correlated with an improvement in the digestibility of maize stem rind tissue.