摘要: In this study, we characterized the role of an apple
cytosolic malate dehydrogenase gene (
MdcyMDH) in the tolerance to salt and cold stresses and investigated its regulation mechanism in stress tolerance. The
MdcyMDH tran MdcyMDH-overexpressing apple plants possessed improved cold and salt tolerance compared to wild-type (WT) plants. A digital gene expression tag profiling analysis revealed that
MdcyMDH overexpression largely altered some biological processes, including hormone signal transduction, photosynthesis, citrate cycle and oxidation–reduction. Further experiments verified that
MdcyMDH overexpression modified the mitochondrial and chloroplast metabolisms and elevated the level of reducing power, primarily caused by increased ascorbate and glutathione, as well as the increased ratios of ascorbate/dehydroascorbate and glutathione/glutathione disulphide, under normal and especially stress conditions. Concurrently, the transgenic plants produced a high H
2O
2 content, but a low
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O2·− production rate was observed compared to the WT plants. On the other hand, the transgenic plants accumulated more free and total salicylic acid (SA) than the WT plants under normal and stress conditions. Taken together,
MdcyMDH conferred the transgenic apple plants a higher stress tolerance by producing more reductive redox states and increasing the SA level;
MdcyMDH could serve as a target gene to genetically engineer salt- and cold-tolerant trees.
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