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在根瘤菌与宿主豆科植物形成的共生关系中,根瘤菌分泌的结瘤因子是宿主专一性的主要决定因子.结瘤因子信号能够诱导豆科植物根毛细胞质膜去极化、离子流动和早期结瘤素基因的表达以及根毛变形、皮层细胞分裂和根瘤原基形成等与共生有关的表型变化.水稻是重要的粮食作物,能否对结瘤因子信号产生应答反应是最终实现水稻结瘤固氮的关键因素.将大豆早期结瘤素基因Gmenod2B的启动子与报告基因β-葡萄糖苷酶(GUS)基因融合构建成嵌合基因Gmenod2Bp-GUS,以此嵌合基因作为探索水稻细胞感受结瘤因子信号的分子标记.通过根癌农杆菌介导的遗传转化系统,获得了携带嵌合基因Gmenod2Bp-GUS的水稻再生植株.以广宿主根瘤菌NGR234(pA28)分泌的结瘤因子作为探针,检测转基因水稻中嵌合基因Gmenod2Bp-GUS的表达.结果表明,转基因水稻中大豆早期结瘤素基因enod2B启动子的表达可以受结瘤因子诱导,仅在水稻根部的皮层薄壁细胞和内皮层细胞中呈特异性表达,并且受到氮源的调控.推测在水稻中可能存在结瘤因子所诱导的豆科早期结瘤素表达的类似机制.
In the symbiotic relationship between Rhizobium and host legumes, the nodulation factor secreted by rhizobia is the major determinant of host specificity, and the nod factors signal can induce the depolarization of plasma membrane and ion flux in legume root hair cells Early nodulin gene expression and root hair deformation, cortical cell division and root nodule formation and other symbiotic related phenotypic changes. Rice is an important food crops, whether the response to the nodulation signal response is the ultimate realization of rice knot Which is the key factor of nitrogen fixation in tumor cells.Genod2Bp-GUS was constructed by fusing the reporter gene Gmenod2B with the reporter gene Gmenod2B into the chimeric gene Gmenod2Bp-GUS, Which is a molecular marker of tumorigenin signal.Recombinant rice plants carrying Gmenod2Bp-GUS, a chimeric gene, were obtained by Agrobacterium tumefaciens-mediated genetic transformation system.The nodulation factor secreted by host rhizobium NGR234 (pA28) , To detect the expression of chimeric gene Gmenod2Bp-GUS in transgenic rice.The results showed that the expression of enod2B promoter of soybean early nodulation gene in transgenic rice Can be induced by nodulation factors and expressed specifically only in the cortex parenchyma cells and endoderm cells in rice roots and is regulated by nitrogen sources.It is presumed that nodulation-induced early nodulation in leguminous plants may exist in rice A similar mechanism of prime expression.