Abstract
Understanding of oil biosynthesis in seed is essential for plant breeding. In oilseed plants, seed accumulates large amount of triacylglycerol. Seeds of Arabidopsis thaliana contain more than 30% of triacylglycerol. We isolated a mutant that had higher density of seed (hs3; heavy seed 3). Triacylglycerol content of hs3 seed is lower than that of wild type seed. HS3 encodes a DEAD box DNA/RNA helicase and HS3 protein localizes in chloroplast. hs3 has defects in post-germinative growth in addition to the defect of oil biosynthesis in seed. The expressions of several genes encoded in chloroplast genome, including acetyl CoA carboxylase (ACCD) are significantly suppressed in hs3. It indicates that HS3 is essential for proper expression of genes in chloroplast genome. These results show that HS3 is a conclusive factor that is involved in both seedling development and oil biosynthesis in seed.
