中文摘要：

【目的】对蒺藜苜蓿MtROP5的功能进行研究,为阐明植物ROP在共生互作过程中的调控机制奠定基础。【方法】采用PCR方法克隆MtROP5的启动子序列,并构建了MtROP5的相关表达载体。利用发根农杆菌介导的遗传转化方法,对MtROP5启动子的表达模式以及MtROP5的功能进行了分析。【结果】克隆了MtROP5翻译起始位点上游2.1 kb左右预测的启动子序列,MtROP5启动子驱动GUS在根系的各个部位中都有表达,在维管束组织和侧根起始的分生组织中表达较强,并且其启动子转录活力在受到根瘤菌侵染后诱导增强表达;MtROP5的过量表达和组成型激活突变均能显著促进根毛的伸长,相比对照转化根系,根毛长度分别增长了74.6%和54.8%,而通过RNAi干扰降低MtROP5的转录水平后,根毛的生长发育明显受到了抑制,其转化根系的根毛缩短了47.6%,但MtROP5显著性失活突变转化根系的根毛长度与对照转化根系没有显著差异。【结论】蒺藜苜蓿MtROP5调节了根毛的生长发育,并可能参与宿主植物与根瘤菌共生互作早期的信号传导过程。

英文摘要：

[ Objective ] The function of MtROP5 in Medicago truncatula was studied for establishment of the groundwork to investigate the regulatory mechanism of ROP in symbiotic interaction. [Method] The promoter sequence of MtROP5 was obtained using PCR, and the expression vectors containing MtROP5 were constructed. The method of Agrobacterium rhizogenes-mediated root transformation was used to investigate the function of MtROP5. [ Result] The sequence of MtROP5 promoter that is at about 2.1 kb upstream of the translation origin point was obtained. The results showed that the MtROP5 promoter allowed GUS expression in every part of the root, GUS displayed more abundant expression level in vascular bundle and initials of lateral root than other parts of root. The transcriptional activity of MtROP5 promoter was induced to increase in the transgenic roots after infected by Sinorhizobium meliloti Rml021. Compared with root hairs of the transgenic root of control, the length of transgenic root hairs of overexpression and constitutively active mutant of MtROP5 increased markedly by 74.6% and 54.8%, respectively, the length of transgenic root hair of RNAi interference of MtROP5 reduced by 47.6%, but the dominantly negative mutant of MtROP5 did not affect the development of root hairs. [ Conclusion ] MtROP5 in M. truncatula regulated the development of root hair, and probably involved in the signal transduction at the early stage of symbiotic interaction between host plant and Rhizobium.