Soybean Cytochrome P450s and The Making of Aliphatic Suberin Monomers
Abstract
18-Hydroxyoleic acid and oleic-1,18-dioic acid are two of the most prominent aliphatic monomers in soybean root suberin. Previous study has demonstrated a positive correlation between CYP86A37 and CYP86A38 expression and the deposition of 18-hydroxyoleic acid in soybean hairy roots. By screening recombinant proteins through in vitro enzyme assays, the substrate specificities of CYP86A37, CYP86A38, and CYP86B9 – another suberin related CYP – were evaluated. Among the three recombinant enzymes, CYP86A38 was not expressed by yeast, whereas CYP86A37 and CYP86B9 exhibited a preference for the ω-hydroxylation of C18:1 and C24:0 fatty acids, respectively. Additionally, in vitro production of oleic-1,18-dioic acid was also detected when CYP86A37 was supplied with C18:1 FA substrate. In planta, CRISPR/Cas9-mediated double knockout of cyp86a37/cyp86a38 in soybeans resulted in significant reduction in most aliphatic suberin monomers, whereas overexpression of CYP86A38 did not result in an enhanced suberin phenotype. These findings underscore the role of the CYP86 subfamily in soybean aliphatic suberin biosynthesis.