Cui Q Q, Chen Y C, Han X J, Zhan Z Y, Lin L Y, Si L L, Wang Y D
State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Beijing, China.
Genet Mol Res. 2013 Dec 11;12(4):6554-64. doi: 10.4238/2013.December.11.7.
The tung tree (Vernicia fordii Hemsl.; Vf) has great potential as an industrial crop owning to its seed oil that has multiple uses. Diacylglycerol acyltransferases (DGATs) catalyze the last and most committed step of triacylglycerol (TAG) biosynthesis. In order to examine the physiological role of the VfDGAT2 gene in the tung tree, we characterized its expression profiles in different tung tissues/organs and seeds at different developmental stages. Oil content and α-eleostearic acid production during seed development were also examined. Expression studies showed that VfDGAT2 was expressed in all tissues tested, with the highest expression in developing seeds where the expression was about 19-fold more than that in leaves. VfDGAT2 showed temporal-specific expression during seed development and maturation. Notably, the expression of VfDGAT2 in developing seeds was found to be consistent with tung oil accumulation and α-eleostearic acid production. The expression level of VfDGAT2 was lower in the early stages of oil accumulation and α-eleostearic acid biosynthesis, rapidly increased during the peak periods of fatty acid synthesis in August, and then decreased during completion of the accumulation period at the end of September. When the VfDGAT2 gene was transferred to the oleaginous yeast Rhodotorula glutinis, its expression was detected along with fatty acid products. The results showed that VfDGAT2 was highly expressed in transgenic yeast clones, and the total fatty acid content in one of these clones, VfDGAT2-3, was 7.8-fold more than that in the control, indicating that VfDGAT2 contributed to fatty acid accumulation into TAG and might be a target gene for improving tung oil composition through genetic engineering.
油桐（Vernicia fordii Hemsl.；Vf）作为一种工业作物具有巨大潜力，因为其种子油具有多种用途。二酰基甘油酰基转移酶（DGATs）催化三酰甘油（TAG）生物合成的最后且最关键的步骤。为了研究VfDGAT2基因在油桐中的生理作用，我们对其在油桐不同组织/器官以及不同发育阶段种子中的表达谱进行了表征。还检测了种子发育过程中的油含量和α - 桐酸产量。表达研究表明，VfDGAT2在所有测试组织中均有表达，在发育中的种子中表达量最高，其表达量比叶片中的高约19倍。VfDGAT2在种子发育和成熟过程中表现出时间特异性表达。值得注意的是，发现VfDGAT2在发育中的种子中的表达与桐油积累和α - 桐酸产量一致。VfDGAT2的表达水平在油积累和α - 桐酸生物合成的早期较低，在8月脂肪酸合成高峰期迅速增加，然后在9月底积累期结束时下降。当VfDGAT2基因转入产油酵母粘红酵母时，其表达与脂肪酸产物一同被检测到。结果表明，VfDGAT2在转基因酵母克隆中高表达，其中一个克隆VfDGAT2 - 3中的总脂肪酸含量比对照高7.8倍，这表明VfDGAT2有助于脂肪酸积累到TAG中，可能是通过基因工程改善桐油成分的靶基因。
