Meng Zhang
College of Agronomy, Northwest A&F University

Triacylglycerol (TAG) biosynthesis is a principal metabolic pathway in most organisms, and TAG is the major form of carbon storage in many plant seeds. Biosynthesis of TAG involves in two main steps, biosynthesis of fatty acid and assembling of TAG. TAG biosynthesis shares nearly all steps with that of membrane lipids except the final step. Dozens of genes involved in the process of TAG biosynthesis and isoenzymes appeared in some reactions, the molecular mechanism of TAG biosynthesis is not entirely understood. Less progress has been made for increasing oil yield by manipulating single gene in transgenic plants. In recent years, we have been focusing on identifying the unique final step of TAG biosynthesis and regulation factors in oil synthesis. Acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) is the only acyltransferase enzyme that has been confirmed to contribute to TAG biosynthesis in Arabidopsis thaliana seeds. However, dgat1 null mutants display only a 20 to 40% decrease in seed oil content. To determine whether other enzymes contribute to TAG synthesis, candidate genes were expressed in TAG-deficient yeast, candidate mutants were crossed with the dgat1-1 mutant, and target genes were suppressed by RNA interference (RNAi). The role of phospholipid: diacylglycerol acyltransferase 1 (PDAT1; At5g13640) in TAG synthesis was revealed in our study. WRI1, LEC1, LEC2 have been reported to be regulators of oil accumulation. One new regulator was identified in our recent study.