【摘要】 为了揭示DNA甲基化在高表达转C₄-PEPC基因水稻植株对干旱耐性的作用,以高表达转玉米C₄型磷酸烯醇式丙酮酸羧化酶（PEPC）基因（C₄-PEPC）水稻（PC）和受体Kitaake（WT）为材料,通过发芽、水培和盆栽试验,研究了施用不同浓度的DNA甲基化抑制剂5-氮杂胞苷（5-azaC）联合干旱处理下,水稻芽期、苗期和生育后期,种子发芽率,苗期叶片的相对含水量、丙二醛、脯氨酸、总可溶性糖及其组分及总可溶性蛋白含量、PEPC酶活性以及C₄-PEPC、与蔗糖非发酵1（SNF1）相关蛋白激酶（SNF1-related protein kinase 1s, SnRK1s）基因以及甲基转移酶基因表达的变化、剑叶的光合参数,并最后考察产量构成因子的变化,结果表明:5-azaC对水稻芽期和苗期干旱胁迫作用浓度呈现剂量效应,即低浓度促进,而高浓度抑制,其中作用浓度:芽期<苗期;而对芽期和苗期有促进和抑制的2个浓度外施于水稻生育后期的水稻植株后,则出现恶化的效应,表现为矮化、剑叶的净光合速率和单株产量下降。在缓解干旱抑制的浓度下,PC苗期的缓解效果好于WT,这种差异的表现与其内源蔗糖、SnRK1s基因以及OsMET1b的表达差异同步,而且PC叶片C₄-PEPC表达对不同浓度的5-azaC处理也呈现剂量效应。综上,DNA甲基化参与了水稻干旱响应,但不同生育期表现不同,其中糖信号在调节DNA甲基化增强PC干旱耐性起重要作用。更多还原

【Abstract】 In order to reveal the effect of DNA methylation under drought stress toward rice with high expression of C₄-PEPC（PC）,germination test, hydroponics experiments and pot experiments respectively were used in this study. By introducing different concentrations of DNA methylation inhibitor（5-Azacytidine, 5-azaC）,the drought simulation treatments combining with the inhibitors were used for the stages of seed germination, seedling and late growth, respectively. The changes including germination rate of seed, the relative water content, malondialdehyde content, proline content, soluble sugar, soluble protein content, PEPC activity and the gene expression levels of related genes, C₄-PEPC genes, SnRK1 s gene, and methyltransferase 1 genes of rice leaves at seedling stage, the photosynthesis characteristics of flag leaves at flowering stage were measured, and their yield component were investigated after harvest as well. The results showed that: In bud and seedling stages, the effect of 5-azaC on drought stress present dose effect in rice as following: promoting under low concentrations and inhibiting under high concentrations, the concentrations of the bud stage<those of seedling stage. But the concentrations with promoting or inhibiting effect on bud and seedling stage of rice had the deteriorative effect during late growth stage with dwarf, low values of net photosynthetic rate and lower grain yield per plants combined with natural drought stress conditions. Mitigation of drought stress in PC was better than that in WT under the promoting concentration, which the drought different performances in PC were synchronized with the differences in endogenous sucrose content, the relative expressions of SnRK1 s gene and OsMET1 b on this concentration of 5-azaC,and the expression of C₄-PEPC in PC also presented the dose effect. In brief, DNA methylation was involved in rice drought response, but the effects were different in different growth stages, and sugar signal might enhance drought tolerance of PC by participating in DNA methylation.更多还原