类囊体膜磷脂酰甘油不饱和度对番茄耐盐性的影响

Overexpression of chloroplastic glycerol-3-phosphate acyltransferase gene (LeGPAT) in tomato increased cis-unsaturated fatty acid content in phosphatidylglycerol (PG) of thylakoid membrane. By contrast, suppressing the expression of LeGPAT decreased the content of cis-unsaturated fatty acid in PG. Under salt stress, sense transgenic plants exhibited higher activities of chloroplastic antioxidant enzymes, lower content of reactive oxygen species (ROS) and less ion leakage compared with the wild type (WT) plants. The net photosynthetic rate (PN) and the maximal photochemical efficiency (Fv/Fm) of PSII decreased more slightly in sense lines but more markedly in antisense lines, compared to WT. D1 protein is located in the reactive center of the PSII, is the primary target of photodamage and has the highest turnover rate in the chloroplast. Under salt stress, compared with WT, the content of D1 protein decreased slightly in sense lines and significantly in antisense lines. In the presence of streptomycin (SM), the net degradation of the damaged D1 protein was faster in sense lines than in other plants. These results suggested that, under salt stress conditions, increasing cis-unsaturated fatty acids in PG by overexpression of LeGPAT can alleviate PSII photoinhibition by accelerating the repair of D1 protein and improving the activity of antioxidant enzymes in chloroplasts.