中文摘要：

在许多种类的细菌中均发现了luxR／luxI类型的群体感应调控系统，其中luxR是调节基因，对luxI合成自体诱导物（AI，autoinducer）起着正调控作用。通过建库筛选后，测序比对发现天山根瘤菌中存在mrtR／mrtI系统。通过基因敲除和转录水平基因表达对mrtR进行研究，发现mrtR严格调控着mrtI的表达，同时mrtR的表达也受到AI影响，这表明mrtR表达的调控是一种自调控，同时根毛吸附实验显示该基因对根瘤菌与宿主间相互作用密切相关。

英文摘要：

The ability of rhizobia to symbiotically fix nitrogen from the atmosphere when forming nodules on their host plant roots requires signal transduction pathways. LuxR/LuxI family proteins are a unique quorum-sensing system, found in many bacteria, LuxR is a regulatory protein which regulates LuxI-type proteins in synthesizing autoinducer （AI）. In this study, sequence analysis was conducted finding a LuxI-type synthase gene, mrtI, and a regulatory gene mrtR present in M. tianshanense, which are homologic to the LuxR/LuxI type of protein. Using gene knock-out, mrtR was found regulating the expression of tutti. Furthermore, and using lacZ transcriptional fusion, AHL molecule demonstrating a key role in mrtR expression, which proves that mrtR is auto-regulated. The root hair adherence experiment showed that mrtR affected plant-bacteria interaction. These data show that it is necessary to have MrtR bonded with AHLs for mrtI expression and the gene plays a key role in regulating the quorum sensing system of M. tianshanense.