Department of Biology, College of Natural Sciences, Kyungpook National University, Daegu 702-701, South Korea.
J Plant Physiol. 2013 Apr 15;170(6):610-8. doi: 10.1016/j.jplph.2012.12.002. Epub 2013 Jan 5.
Various environmental stresses induce reactive oxygen species (ROS), causing deleterious effects on plant cells. Glutathione (GSH), a critical antioxidant, is used to combat ROS. GSH is produced by γ-glutamylcysteine synthetase (γ-ECS) and glutathione synthetase (GS). To evaluate the functional roles of the Oryza sativa L. Japonica cv. Ilmi ECS (OsECS) gene, we generated transgenic rice plants overexpressing OsECS under the control of an inducible promoter (Rab21). When grown under saline conditions (100mM) for 4 weeks, 2-independent transgenic (TGR1 and TGR2) rice plants remained bright green in comparison to control wild-type (WT) rice plants. TGR1 and TGR2 rice plants also showed a higher GSH/GSSG ratio than did WT rice plants in the presence of 100mM NaCl, which led to enhanced redox homeostasis. TGR1 and TGR2 rice plants also showed lower ion leakage and higher chlorophyll-fluorescence when exposed to 10μM methyl viologen (MV). Furthermore, the TGR1 and TGR2 rice seeds had approximately 1.5-fold higher germination rates in the presence of 200mM salt. Under paddy field conditions, OsECS-overexpression in transgenic rice plants increased rice grain yield (TGW) and improved biomass. Overall, our results show that OsECS overexpression in transgenic rice increases tolerance and germination rate in the presence of abiotic stress by improving redox homeostasis via an enhanced GSH pool. Our findings suggest that increases in grain yield by OsECS overexpression could improve crop yields under natural environmental conditions.
各种环境胁迫会诱导活性氧（ROS）的产生，对植物细胞造成有害影响。谷胱甘肽（GSH）是一种重要的抗氧化剂，可用于抵御 ROS。GSH 是由γ-谷氨酰半胱氨酸合成酶（γ-ECS）和谷胱甘肽合成酶（GS）产生的。为了评估水稻（Oryza sativa L. Japonica cv. Ilmi）ECS（OsECS）基因的功能作用，我们利用诱导型启动子（Rab21）在水稻中过表达 OsECS，从而生成了转基因水稻植株。当在盐胁迫条件（100mM）下生长 4 周时，与对照野生型（WT）水稻植株相比，2 个独立的转基因（TGR1 和 TGR2）水稻植株仍保持鲜绿。在 100mM NaCl 存在的情况下，TGR1 和 TGR2 水稻植株的 GSH/GSSG 比值也高于 WT 水稻植株，这导致了氧化还原稳态的增强。当暴露于 10μM 甲基紫精（MV）时，TGR1 和 TGR2 水稻植株的离子渗漏率较低，叶绿素荧光较高。此外，在存在 200mM 盐的情况下，TGR1 和 TGR2 水稻种子的发芽率约提高了 1.5 倍。在稻田条件下，转基因水稻中 OsECS 的过表达增加了水稻粒重（TGW），并改善了生物量。总的来说，我们的结果表明，通过提高 GSH 池，过表达 OsECS 可改善氧化还原稳态，从而提高转基因水稻对非生物胁迫的耐受性和发芽率。我们的研究结果表明，通过过表达 OsECS 提高籽粒产量可以在自然环境条件下提高作物产量。
