Effect of increase in unsaturation of thylakoid membrane lipids on salt tolerance in tomato plants

Chinese. 【目的】探讨类囊体膜脂脂肪酸组成与耐盐性的关系。【方法】以野生型（WT），转反义番茄叶绿体ω-3脂肪酸去饱和酶（LeFAD7）基因株系T2-8（-）和转正义LeFAD7基因株系T2-7（＋）为试材，测定了类囊体膜脂脂肪酸组成，盐胁迫后的光合参数，叶绿素荧光参数和叶绿体活性氧清除酶活性。【结果】转正义基因番茄植株类囊体膜脂中亚麻酸（18：3）含量升高，亚油酸（18：2）含量下降，导致膜脂脂肪酸不饱和程度升高，而转反义基因番茄植株类囊体膜脂不饱和脂肪酸含量下降。盐胁迫下亚麻酸含量高的转正义基因植株的PSII最大光化学效率（Fv/Fm）和光合速率（Pn）下降程度较小，而转反义基因植株的下降程度较大。与WT相比，盐胁迫下转正义基因植株维持较高的叶绿体超氧化物歧化酶（SOD）和抗坏血酸过氧化物酶（APX）活性， 和H2O2的含量较低。【结论】番茄类囊体膜脂不饱和脂肪酸含量的增加提高了番茄光合机构的耐盐性。

English. [Objective] The aim of this study is to investigate the correlation between fatty acid composition in thylakoid membrane and the tolerance to salt stress. [Method] WT, antisense- transgenic lines T2-8（-） and sense-transgenic lines T2-7（＋） of tomato were used to measure the fatty acid composition of thylakoid membrane, photosynthetic and chlorophyll fluorescence parameters, chloroplastic reactive oxygen species and activities of antioxidant enzymes under salt stress. [ Result ] Linolenic acid （18 ： 3） obviously increased and the content of oleic acid （18 ： 2） concomitantly reduced in the sense-transgenic lines, resulting in the increase of the unsaturation of thylakoid membrane lipids. In contrast, the decreased unsaturation of thylakoid membrane lipids in antisense-transgenic plants was observed. The maximal photochemical efficiency of PS II （Fv/Fm） and photosynthetic rates （Pn） in T2-7（＋） lines with higher 18：3 decreased less under salt stress, while Fv/Fm and Pn in T2-8（-） lines decreased obviously. Compared to WT, the sense-transgenic lines could maintain higher activities of chloroplastic SOD and APX, lower content of chloroplastic O2. _ and H2O2 under salt stress. [Conclusion] Higher unsaturation of thylakoid membrane lipids enhanced the tolerance of tomato photosynthetic apparatus to salt stress.