Overexpression in tobacco of a tomato GMPase gene improves tolerance to both low and high temperature stress by enhancing antioxidation capacity |
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Authors: | Wang Hua-Sen Yu Chao Zhu Zhu-Jun Yu Xian-Chang |
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Institution: | (1) Department of Horticulture, School of Agriculture and Food Science, Zhejiang A and F University, Lin’an, 311300, Zhejiang, People’s Republic of China;(2) The Institute of Vegetables and Flowers, Chinese Academy of Agricultural Science, Beijing, 10081, People’s Republic of China; |
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Abstract: | GDP-mannose pyrophosphorylase (GMPase: EC 2.7.7.22) plays a crucial role in the synthesis of l-ascorbate (AsA) and the consequent detoxification of reactive oxygen species (ROS). Herein, a GMPase (accession ID DQ449030) was identified and cloned from tomato. The full-length cDNA sequence of this gene contains 1,498 bp
nucleotides encoding a putative protein with 361 amino acid residues of approximate molecular weight 43 kDa. Northern blot
analysis revealed that the GMPase was expressed in all examined tomato tissues, but its expression level was up-regulated in tomato plants subjected to abnormal
temperatures. We then overexpressed this tomato GMPase in tobacco plants and observed that the activity of GMPase and the content of AsA were significantly increased by two- to
fourfold in the leaves of transgenic tobacco plants. The effect of this gene overexpression was superimposed by the treatments
of high or low temperature in tobacco, since the activities of both chloroplastic SOD (superoxide dismutase EC 1.15.1.1),
APX (ascorbate peroxidase EC 1.11.1.7) and the content of AsA in leaves were significantly higher in transgenic plants than
those of WT, while the contents of H2O2 and O2
−· were reduced. Meanwhile, relative electric conductivity increased less in transgenic plants than that in WT, and the net
photosynthetic rate (P
n) and the maximal photochemical efficiency of PSII (F
v/F
m) of transgenic plants were notably higher than those of WT under temperature stresses. In conclusion, the overexpression
of GMPase increased the content of AsA, thereby leading to the increase in tolerance to temperature stress in transgenic plants. |
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