Overexpression of SlGMEs leads to ascorbate accumulation with enhanced oxidative stress, cold, and salt tolerance in tomato
Overexpression of SlGMEs leads to ascorbate accumulation with enhanced oxidative stress, cold, and salt tolerance in tomato
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DOI：
10.1007/s00299-010-0939-0
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发表时间：
2011-03
影响因子：
6.2
通讯作者：
Chanjuan Zhang;Junxia Liu;Yuyang Zhang;Xiaofeng Cai;Pengjuan Gong;Junhong Zhang;Taotao Wang;Hanxia Li
中科院分区：
文献类型：
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作者：
Chanjuan Zhang;Junxia Liu;Yuyang Zhang;Xiaofeng Cai;Pengjuan Gong;Junhong Zhang;Taotao Wang;Hanxia Li
Gdp-甘露糖3‘，5’-差向异构酶(GME；EC 5.1.3.18)催化GDp-d-甘露糖转化为GDp-L-半乳糖，这是高等植物抗坏血酸生物合成途径中的重要步骤。在本研究中，从番茄(Solanum Lycopsicum)中分离到GME基因家族的两个成员。这两个基因编码376个氨基酸，它们之间有92%的相似性。半定量RT-PCR结果显示，SLGME1在不同组织中持续表达，而SLGME2在不同组织中有差异表达。在洋葱细胞中瞬时表达融合的slGME1-GFP(绿色荧光蛋白)和slGME2-GFP显示了这两种蛋白的胞质定位。与野生型植株相比，过量表达SLGME1和SLGME2的转基因植株叶片和红果中总抗坏血酸含量显著增加。在甲基紫精(百草枯)胁迫下，它们表现出较低的叶绿素含量损失和膜脂过氧化，在低温胁迫下表现出较高的存活率，在盐胁迫下显著提高种子发芽率、鲜重和根长，表现出较强的耐逆性。本研究表明，GME基因家族的两个成员的过表达导致番茄中抗坏血酸的积累增加，并提高了对非生物胁迫的耐受性。
GDP-Mannose 3′,5′-epimerase (GME; EC 5.1.3.18) catalyses the conversion of GDP-d-mannose to GDP-l-galactose, an important step in the ascorbic acid (AsA) biosynthesis pathway in higher plants. In this study, two members of theGMEgene family were isolated from tomato (Solanum lycopersicum). BothSlGMEgenes encode 376 amino acids and share a 92% similarity with each other. Semi-quantitative RT-PCR indicated thatSlGME1was constantly expressed in various tissues, whereasSlGME2was differentially expressed in different tissues. Transient expression of fusedSlGME1-GFP(green fluorescent protein) andSlGME2-GFPin onion cells revealed the cytoplasmic localisation of the two proteins. Transgenic plants over-expressingSlGME1andSlGME2exhibited a significant increase in total ascorbic acid in leaves and red fruits compared with wild-type plants. They also showed enhanced stress tolerance based on less chlorophyll content loss and membrane-lipid peroxidation under methyl viologen (paraquat) stress, higher survival rate under cold stress, and significantly higher seed germination rate, fresh weight, and root length under salt stress. The present study demonstrates that the overexpression of two members of theGMEgene family resulted in increased ascorbate accumulation in tomato and improved tolerance to abiotic stresses.