Li Dapeng, Shen Jin, Wu Tao, Xu Yunfeng, Zong Xiaojuan, Li Dequan, Shu Huairui
College of Food Sciences, Shandong Agricultural University, Tai'an, Shandong 271018, P.R. China.
Physiol Plant. 2008 Nov;134(3):394-402. doi: 10.1111/j.1399-3054.2008.01152.x. Epub 2008 Jul 31.
Alcohol acyltransferases (AATs) are key enzymes in ester biosynthesis. Previous studies have found that AAT may be a stress-related gene. To investigate further the function of the apple alcohol acyltransferase gene (MdAAT2), transgenic tobacco plants overexpressing MdAAT2 were generated. Gas chromatography-mass spectroscopy analysis showed that the volatile blends were altered in these transgenic tobacco leaves. Although no apple-fruity volatile esters were detected in transgenic tobacco leaves, methyl caprylate, methyl caprate, and methyl dodecanoate were newly generated, and the concentrations of methyl benzoate and methyl tetradecanoate were significantly increased, suggesting that MdAAT2 may use medium-chain fatty acyl CoA and benzoyl-CoA as acyl donors together with methanol acceptors as substrates. Surprisingly, the concentrations of linalool were significantly increased in transgenic tobacco leaves, which may mediate the repellent effect on Myzus persicae (Sulzer) aphids. Using methyl jasmonate (MeJA) and wounding treatments, we found that MdAAT2 may substitute for the partial ability of MeJA to induce the production of linalool in transgenic plants. These data suggest that MdAAT2 may be involved in the response to the MeJA signal and may play a role in the response to biotic and abiotic stress.
酒精酰基转移酶（AATs）是酯生物合成中的关键酶。先前的研究发现，AAT可能是一个与胁迫相关的基因。为了进一步研究苹果酒精酰基转移酶基因（MdAAT2）的功能，构建了过表达MdAAT2的转基因烟草植株。气相色谱-质谱分析表明，这些转基因烟草叶片中的挥发性混合物发生了变化。尽管在转基因烟草叶片中未检测到苹果味挥发性酯，但新生成了辛酸甲酯、癸酸甲酯和十二烷酸甲酯，苯甲酸甲酯和十四烷酸甲酯的浓度显著增加，这表明MdAAT2可能以中链脂肪酰辅酶A和苯甲酰辅酶A作为酰基供体，甲醇作为受体底物。令人惊讶的是，转基因烟草叶片中芳樟醇的浓度显著增加，这可能介导了对桃蚜（Sulzer）的驱避作用。通过茉莉酸甲酯（MeJA）和机械损伤处理，我们发现MdAAT2可能替代了MeJA在转基因植物中诱导芳樟醇产生的部分能力。这些数据表明，MdAAT2可能参与对MeJA信号的响应，并可能在生物和非生物胁迫响应中发挥作用。
