甜菜碱提高番茄种子的耐热性

omato (Lycopersicon esculentum cv. 'Moneymaker') was transformed with a codA gene, from Arthrobacter globiformis, for choline oxidase that had been modified to allow targeting to both chloroplasts and the cytosol. Glycinebetaine (GB) accumulated in seeds of transformed plants up to 1 μmol g-1 DW, while no detectable GB was found in wild-type seeds. The codA-transgenic seeds germinated faster and at higher frequency than wild-type seeds with high temperature treatment. After heat stress, levels of expression of a mitochondrial small heat-shock protein (MT-sHSP), heat-shock protein 70 (HSP70), and heat shock cognate 70 (HSC70) were higher in transgenic seeds than in wild-type seeds during heat stress, and the accumulation of HSP70 was more prominent in codA-transgenic seeds than in wild-type seeds. Addition of GB to the germination medium or imbibition of seeds in a solution of GB enhanced the tolerance of wild-type seeds to high temperatures. Wild-type seeds treated with exogenous GB also expressed heat-shock genes at elevated levels and accumulated more HSP70 than controls. Our results suggest that GB, either applied exogenously or accumulated in vivo in codA-transgenic seeds, enhanced the expression of heat-shock genes in and improved the tolerance to high temperature of tomato seeds during germination.