Fatty acid ω-hydroxylases of soybean: CYP86A gene expression and aliphatic suberin deposition

Abstract

Suberin has been shown to play a role in protection against and response to stress, including defense against soil-borne pathogens. In soybean, oxidized fatty acids are the most predominant monomers contributing to root suberin, with 18-hydroxy-oleic acid being the most abundant. 18-Hydroxy-oleic acid is predicted to be synthesized by members of the CYP86A family of cytochrome P450 enzyme. Six putative CYP86A genes were identified through phylogenetic analysis of the soybean genome. Two of these, CYP86A37 and CYP86A38 show a root-specific gene expression pattern, and were further analyzed to assess their physiological role in suberin deposition using RNAi knockdown in a hairy root system. Soybean hairy roots were found to be nearly identical to soil-grown roots in terms of anatomy, suberin deposition patterns, and suberin chemistry. The RNAi knockdown of CYP86A37 and CYP86A38 yielded hairy root lines with reduced gene expression and a reduction in the oxidized monomers of suberin, most notably 18-hydroxy-oleic acid. Based on this evidence, CYP86A37 and CYP86A38 are predicted to function as fatty acid ω-hydroxylases in vivo.