Down-regulated expression of the palmitoyl-acyl carrier protein thioesterase (FatB) gene enhanced oleic and linoleic acid accumulation in rice (Oryza sativa) seed

Background Rice ( Oryza sativa ) seed lipids contain about 25% saturated fatty acids, dominated by palmitic acid. Reduction of saturated fat consumption is recommended for health concerns and so reducing palmitic acid content is of interest for the rice bran oil industry. In higher plants, palmitoyl-acyl carrier protein thioesterase (FatB) controls the release of palmitic acid from acyl carrier protein and its accumulation in oil. Results In this study, four rice OsFatB genes were identified, and their expression patterns were analyzed in seed by the reverse-transcription quantitative PCR. Two types of rice lines were obtained with down-regulated OsFatB expression: an OsFatB1 knockout mutant obtained via Tos17 insertion and transgenic rice lines in which expression of the four OsFatB genes using RNAi technology. Both types exhibited partial reductions of palmitic acid content (11% and 21–55%, respectively) and a slight reduction in myristic acid content. Increased oleic and linoleic acid content was observed in the transgenic rice lines but not in the Tos17 insertion line. Conclusion These results demonstrated that the palmitic acid content is controlled by multiple OsFatBs , and the contribution of OsFatB1 is limited.