Variant castor lysophosphatidic acid acyltransferases acylate ricinoleic acid in seed oil

초록

Determining the role of castor lysophosphatidic acid acyltransferases (RcLPATs) provides information that aid in understanding the biosynthesis mechanism of castor oil (triacylglycerols, TAG), which contains 90 % ricinoleic acid (18:1OH), a hydroxy fatty acid (HFA) with numerous industrial applications. The entire family of seven RcLPATs was shown to encode functional enzymes using in vitro assays. Gene expression analysis suggested that RcLPATs play roles in various vegetative and reproductive organs by associating with membrane lipid and TAG biosynthesis. To identify isoforms of RcLPATs capable of acylating 18:1OH, individual RcLPATs were expressed in CL37, an Arabidopsis line containing approximately 17 % HFA in seed TAG. Transgenics expressing RcLPAT2, RcLPAT3B, or RcLPATB increased total HFA to 18.2 %-20.3 %. Furthermore, different accumulation levels of 18:1OH and densipolic acid (18:2OH) were detected among these three transgenic backgrounds. The mechanisms of substrate selectivity among RcLPAT2, RcLPAT3B, and RcLPATB are discussed.

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