Zhang Chen, Li Xia, He Yafei, Zhang Jinfei, Yan Ting, Liu Xiaolong
Institute of Food and Crops, Jiangsu Academy of Agricultural Sciences Nanjing 210014, PR China; College of Life Science, Nanjing Agricultural University, Nanjing 210095, PR China.
Institute of Food and Crops, Jiangsu Academy of Agricultural Sciences Nanjing 210014, PR China; College of Life Science, Nanjing Agricultural University, Nanjing 210095, PR China.
Plant Physiol Biochem. 2017 Jun;115:328-342. doi: 10.1016/j.plaphy.2017.03.019. Epub 2017 Mar 30.
We compared the drought tolerance of wild-type (WT) and transgenic rice plants (PC) over-expressing the maize CPEPC gene, which encodes phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) gene, and evaluated the roles of saccharide and sugar-related enzymes in the drought response. Pot-grown seedlings were subjected to real drought conditions outdoors, and the yield components were compared between PC and untransformed wild-type (WT) plants. The stable yield from PC plants was associated with higher net photosynthetic rate under the real drought treatment. The physiological characters of WT and PC seedlings under a simulated drought treatment (25% (w/v) polyethylene glycol-6000 for 3 h; PEG 6000 treatment) were analyzed in detail for the early response of drought. The relative water content was higher in PC than in WT, and PEPC activity and the C-PEPC transcript level in PC were elevated under the simulated drought conditions. The endogenous saccharide responses also differed between PC and WT under simulated drought stress. The higher sugar decomposition rate in PC than in WT under drought analog stress was related to the increased activities of sucrose phosphate synthase, sucrose synthase, acid invertase, and neutral invertase, increased transcript levels of VIN1, CIN1, NIN1, SUT2, SUT4, and SUT5, and increased activities of superoxide dismutase and peroxidase in the leaves. The greater antioxidant defense capacity of PC and its relationship with saccharide metabolism was one of the reasons for the improved drought tolerance. In conclusion, PEPC effectively alleviated oxidative damage and enhanced the drought tolerance in rice plants, which were more related to the increase of the endogenous saccharide decomposition. These findings show that components of C photosynthesis can be used to increase the yield of rice under drought conditions.
我们比较了野生型（WT）和过表达玉米CPEPC基因的转基因水稻植株（PC）的耐旱性，该基因编码磷酸烯醇式丙酮酸羧化酶（PEPC，EC 4.1.1.31）基因，并评估了糖类和糖相关酶在干旱响应中的作用。将盆栽幼苗置于室外真实干旱条件下，比较了PC植株和未转化的野生型（WT）植株的产量构成因素。在真实干旱处理下，PC植株稳定的产量与较高的净光合速率相关。详细分析了WT和PC幼苗在模拟干旱处理（25%（w/v）聚乙二醇-6000处理3小时；PEG 6000处理）下的生理特征，以研究干旱的早期响应。PC中的相对含水量高于WT，并且在模拟干旱条件下，PC中的PEPC活性和C-PEPC转录水平升高。在模拟干旱胁迫下，PC和WT之间的内源糖类响应也有所不同。在干旱模拟胁迫下，PC中比WT更高的糖分解速率与蔗糖磷酸合酶、蔗糖合酶、酸性转化酶和中性转化酶活性增加、VIN1、CIN1、NIN1、SUT2、SUT4和SUT5转录水平增加以及叶片中超氧化物歧化酶和过氧化物酶活性增加有关。PC更强的抗氧化防御能力及其与糖类代谢的关系是耐旱性提高的原因之一。总之，PEPC有效减轻了氧化损伤并增强了水稻植株的耐旱性，这与内源糖类分解的增加更相关。这些发现表明，C4光合作用的组分可用于提高干旱条件下水稻的产量。
