Abstract
During the maturation of Arabidopsis seeds, a large portion of sugar carbons imported from the source are converted into oil for storage. An AP2-type transcription factor ASML1/WRI1 directly activates genes for fatty acid synthesis in the plastid, while expression of genes for the synthesis of triacylglycerol (TAG) in the endoplasmic reticulum requires other factor(s). To search for factors involved in the regulation of TAG synthesis, we introduced a LUC reporter gene with the promoter of a gene for diacylglycerol acyltransferase (DGAT1). The DGAT1p::LUC transgenic plants showed strong LUC expression in fruits and weaker expression in young leaves, which is similar to the expression pattern of DGAT1. We carried out enhancer activation-tag screening for mutants with enhanced expression of LUC in seedlings. Among lines which showed enhanced LUC expression in seedlings of the second generation, #14-3 also showed enhanced level of DGAT1 mRNA. One of the genes near the enhancer T-DNA in the genome of #14-3 showed expression during seed maturation similar to DGAT1 and overexpression of this gene in the DGAT1p::LUC plant caused enhancement of LUC activity and the level of DGAT1 mRNA.
