Genetic control of alfalfa infection by the nitrogen fixing symbiotic bacterium Sinorhizobium meliloti

在苜蓿根部形成固氮根瘤是由嗜嗜嗜嗜菌侵染所致。这种植物-微生物相互作用是一个复杂的发育过程，是研究共生固氮的模式系统。我们的研究项目使用细菌遗传工具来研究ExoS-ChvI转录调控系统对感染的控制，该系统直接或间接地协调大量基因的表达。我们正在对这一调控系统进行详细的表征，以确定其在控制感染方面的作用。DNA结合筛选用于准确确定该系统直接关闭和打开的基因，我们将通过结合Illumina DNA测序技术来改进筛选。我们将尝试确定诱导信号，并将调控系统突变体的多效表型与单个靶基因突变体的表型进行比较。我们的工作有可能大大提高我们对感染过程的理解，这不仅会影响农业共生固氮的改进，而且还会通过进一步发展细菌分子遗传学的基础，为我们的整体研究计划做出贡献。这项工作将由研究生在一个智力刺激，活跃的研究环境中进行。

Nitrogen fixing nodules form on alfalfa roots as a result of infection by Sinorhizobium meliloti bacteria. This plant-microbe interaction is a complex developmental process that is a model system for study of symbiotic nitrogen fixation. Our research program uses bacterial genetic tools to study the control of infection by the ExoS-ChvI transcriptional regulatory system that coordinates the expression of a large number of genes both directly and indirectly. We are carrying out a detailed characterization of this regulatory system in an effort to determine its role in controlling infection. DNA binding screens are used to determine exactly which genes are directly turned off and on by this system, and we will improve the screen by incorporating Illumina DNA sequencing technology. We will try to determine the inducing signal, and we will also compare the pleiotropic phenotype of mutants of the regulatory system with the phenotypes of mutants of the individual target genes. Our work has the potential to greatly improve our understanding of the infection process, and this will impact not only on agricultural symbiotic nitrogen fixation improvements, but will also contribute to our overall research program by further developing the fundamentals of bacterial molecular genetics. The work will be carried out by graduate students, in an intellectually stimulating, active research environment.