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为了研究高表达转玉米C_4-磷酸烯醇式丙酮酸羧化酶(phosphoenolpyruvate carboxylase,PEPC)基因水稻(PC)的耐旱性机制,本研究以PC和未转基因野生型原种kitaake为材料,分别在光照和黑暗预处理24 h,其中光照处理中光强为600μmol·m~(-2)·s-1,预处理后稻苗再在15%聚乙二醇-6000模拟干旱胁迫下,同时使用药理学的方法,通过加入脱落酸和己糖激酶的专一性抑制剂100μmol·L~(-1)去甲二氢愈创木酸和10 mmol·L~(-1)葡萄糖胺,观察两种水稻4~5叶期稻苗耐旱表现。结果发现,与WT水稻相比,在PEG-6000处理后,经过光预处理的PC水稻叶片相对含水量下降较少,始终比WT的高,而且丙二醛含量则较少,脯氨酸诱导增加,表现耐旱;而经过暗预处理后PC植株显著降低这个优势,表明光预处理有利于PC耐旱性的表现;黑暗预处理均显著下调了2供试材料植株叶片中可溶性糖的含量,而对可溶性蛋白的含量影响不显著;而光预处理后PC水稻叶片内可溶性糖含量比WT增加,而在黑暗预处理则PC的显著低于WT的,其中葡萄糖胺对光预处理下PC的可溶性糖含量的下调作用最显著;暗预处理逆转或消除了NO,H_2O_2和钙离子含量变化趋势,这些变化与暗预处理减少了两材料叶片蔗糖和葡萄糖含量变化同步;光暗预处理对两材料的PEPC酶活性的差异影响不大,表明外源玉米C4-PEPC在水稻中是组成型表达。可见PC叶片可部分通过糖组分,参与内源糖介导ABA和HXK信号途径,缓解干旱处理对叶片的伤害,稳定光合能力。
In order to study the mechanism of drought tolerance in transgenic rice (PEPC) transgenic rice with high expression of P_ (C_4), we used kitaake of PC and non-transgenic wild-type elite as material, Under light and dark pretreatment for 24 h, the light intensity was 600 μmol · m -2 (-2) · s-1 in the light treatment, and under the simulated drought stress of 15% polyethylene glycol-6000 Pharmacological methods were used to observe the effects of both dihydroguajuronic acid and 10 mmol·L -1 glucosamine by adding 100 μmol·L -1 specific inhibitor of abscisic acid and hexokinase Drought tolerance of rice seedlings in 4 ~ 5 leaf stage. The results showed that compared with WT rice, light-pretreated PC-treated rice leaves had a lower relative water content than WT, higher PEG content and less malondialdehyde than proline-induced PEG-6000 Increased, indicating drought tolerance; PC plants under dark pretreatment significantly reduced this advantage, indicating that light pretreatment is conducive to the performance of PC drought; dark pretreatment significantly decreased the soluble sugar content of 2 leaves of the test material , But had no significant effect on the content of soluble protein. However, the content of soluble sugar in PC leaves increased with light pretreatment, while that in dark pretreatment was significantly lower than that in WT, The dark brown pretreatment reverses or eliminates the trend of NO, H_2O_2 and calcium ion content. These changes are in synch with the changes of sucrose and glucose content in leaves of the two materials under dark pretreatment; The difference of PEPC enzyme activity between the two materials had little effect, indicating that exogenous corn C4-PEPC is constitutively expressed in rice. It can be seen that PC leaves can partly through the sugar components, participate in the endogenous sugar-mediated ABA and HXK signaling pathways, to alleviate the damage of the drought treatment on the leaves and stabilize the photosynthetic capacity.