title: The enhancement of tolerance to salt and cold stresses by modifying the redox state and salicylic acid content via the cytosolic malate dehydrogenase gene in transgenic apple plants.
abstract: 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 transcript was induced by mild cold and salt treatments, and 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 H2 O2 content, but a low 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.
authors.affiliation: State Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong, China.
authors.forename: Qing-Jie
authors.initials: QJ
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Sun
authors.affiliation: State Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong, China.
authors.forename: Qing-Long
authors.initials: QL
authors.lastname: Dong
authors.affiliation: State Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong, China.
authors.forename: Tian-Yu
authors.initials: TY
authors.lastname: Sun
authors.affiliation: State Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong, China.
authors.forename: Zhong-Xin
authors.initials: ZX
authors.lastname: Jin
authors.affiliation: State Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong, China.
authors.forename: Yu-Jin
authors.initials: YJ
authors.lastname: Hao
authors.affiliation: State Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong, China. yaoyx@sdau.edu.cn.
authors.forename: Yu-Xin
authors.initials: YX
authors.lastname: Yao
mesh_terms: D003600:Cytosol / Q000201:enzymology; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D008291:Malate Dehydrogenase / Q000235:genetics* / Q000378:metabolism*; D027845:Malus / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D010084:Oxidation-Reduction; D010788:Photosynthesis / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D020156:Salicylic Acid / Q000378:metabolism; D055049:Salt Tolerance / Q000235:genetics; D013312:Stress, Physiological / Q000235:genetics*
chemical_list: D010940:Plant Proteins; D008291:Malate Dehydrogenase; D020156:Salicylic Acid
keywords: apple (Malus domestica B.); cytosolic malate dehydrogenase gene; overexpression; redox state; salicylic acid; salt and cold tolerance