过量表达叶绿体小分子热激蛋白提高番茄的抗寒性

小分子热激蛋白与植物耐寒性提高有相关性,但是没有直接的实验证据能证明小分子热激蛋白的存在增加植物抗寒性.我们克隆了番茄叶绿体(定位)小分子热激蛋白cDNA,并将35SCaMV启动子驱动的番茄叶绿体小分子热激蛋白cDNA植物表达构架导入番茄,测定转基因番茄和未转基因番茄的抗寒性水平.低温处理后,转基因番茄的冷害症状轻于未转基因的番茄;转基因番茄细胞电解质外渗较少、花青素和MDA累积量较低;净光合速率和叶绿体含量高于对照.这些实验结果说明叶绿体小分子热激蛋白的过量表达提高了植物抗寒性.

Overexpression of Chloroplast-localized Small Molecular Heat-shock Protein Enhances Chilling Tolerance in Tomato Plant

There are many reports about the correla-tion between small molecular heat-shock protein(sHSP) and the acquirement of chilling tolerance, butno direct evidence that sHSP confers enhanced chill-ing tolerance to plant has been reported. A DNAconstruct, including tomato chloroplast-localized smallmolecular heat-shock protein (CPsHSP) cDNA underthe control of cauliflower mosaic virus 35S (35SCaMV)promoter, was introduced into the genome of tomatoplants. The chilling tolerance of the transgenic tomatolines and the non-transgenic tomato was evaluated.After exposure to chilling stress, the transgenic plantsexhibited lighter chilling-injured symptoms, sufferedless electrolyte leakage and less destruction ofchlorophyll, accumulated less anthocyanins and lessMDA and kept higher value of net photosynthetic rate,than non-transgenic plant. All results indicated consis-tently that transgenic tomato plants had stronger chill-ing tolerance. These characters are ascribed to con-stitutive expression of cpshsp and lead to the conclu-sion that HSP can enhance chilling tolerance in plant.