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磷酸烯醇式丙酮酸羧化酶(PEPC)通过固定二氧化碳参与光合作用,是关键的C4植物光合作用酶。为了揭示高光效转C4 PEPC基因水稻(Oryza sativa)对干旱胁迫的适应机理,以高表达转C4 PEPC水稻(PC)和野生型水稻Kitaake(WT)为供试材料,在植株的4–5叶期,使用不同浓度外源Ca Cl2溶液处理,测定在15%聚乙二醇6000(polyethylene glycol-6000,PEG-6000)胁迫下叶片相对含水量、光合参数、内源钙总含量、叶片总蛋白激酶活性、PEPC酶活性以及相关基因表达和蛋白质含量。结果表明,0.5 mmol·L–1 Ca Cl2明显提高PC叶片相对含水量(P<0.05),2 mmol·L–1和10 mmol·L–1 CaC l2则作用不显著,对WT则影响不显著。不同浓度钙处理对PEG处理PC的净光合速率影响不显著,而通过维持气孔导度减少水分胁迫。内源总钙浓度的数据显示,在PEG6000处理下,PC具有维持稳定内源Ca2+浓度的能力,过高浓度(10 mmol·L–1 Ca Cl2)钙处理反而降低了PEPC酶活性、PEPC基因表达和可溶性蛋白的含量。
Phosphoenolpyruvate carboxylase (PEPC) is a key C4 plant photosynthetic enzyme that participates in photosynthesis by fixing carbon dioxide. In order to reveal the adaptive mechanism of high light-efficiency C4PEPC-transgenic rice (Oryza sativa) to drought stress, C4PEPC rice (Oryza sativa) and wild-type Kitaake (WT) The relative water content, photosynthetic parameters, total content of endogenous calcium, total protein content of leaves in 15% polyethylene glycol-6000 (PEG-6000) were determined by using different concentrations of exogenous CaCl 2 solution. Kinase activity, PEPC enzyme activity and related gene expression and protein content. The results showed that 0.5 mmol·L -1 CaCl 2 significantly increased the relative water content of PC leaves (P <0.05), while 2 mmol·L -1 and 10 mmol·L -1 CaCl 2 had no significant effect on WT but no significant effect on WT . Different concentrations of calcium treatment had no significant effect on the net photosynthetic rate of PC, but decreased stomatal conductance to reduce the water stress. The data of endogenous total calcium concentration showed that PC had the ability of maintaining stable endogenous Ca2 + concentration under the PEG6000 treatment. However, the treatment with 10 mmol·L-1 CaCl2 excessively decreased the PEPC enzyme activity and the expression of PEPC gene And soluble protein content.