Bacteroid development in rhizobia

根瘤菌中的类杆菌发育

• 批准号: 288281-2006
• 负责人: Yost, Christopher
• 金额: $ 2.82万
• 依托单位: University of Regina
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2006
• 资助国家: 加拿大
• 起止时间: 2006-01-01 至 2007-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=337422
• 关键词: Bacteroid; development; rhizobia

The biological fixation of atmospheric nitrogen is a critical component to the global nitrogen cycle and is particularly valuable to worldwide agriculture. Globally, nitrogen fixation symbioses between rhizobia and legumes are the major source of nitrogen input to agricultural systems, and many legume species, such as peas, lentils, soybeans and chickpeas are important food crops. Rhizobial-legume interactions have been studied extensively, but the process is complex and further fundamental research is required to appreciate this complexity fully. Rhizobia induce the formation of root nodules on legume plants, and within these nodules, the bacteria convert atmospheric nitrogen to a form that is useable by the plants.  The dramatic transformation that occurs when rhizobia differentiate into symbiont cells (bacteroids) has been clearly documented by recent microarray gene expression and proteomic studies. However, the mechanisms that regulate bacteroid differentiation, particularly the down-regulation of gene expression during nodulation, are largely unknown. The long-term objectives of my research program are to use genetics based methodologies to discover unknown regulatory pathways that control bacteroid development in rhizobia and to identify novel genes required for bacteroid development. More specifically, the proposed research will identify regulators and signals that control the down-regulation of genes related to cellular division, motility and outer membrane proteins during bacteroid development. The role of proteases as regulators of bacteroid development will also be studied in this proposal. Results from this research may be applied to other bacterial-host relationships, particularly pathogenic interactions within the alpha-proteobacteria class, possibly to identify novel mechanisms that regulate the pathogenic process.

大气氮的生物固定是全球氮循环的关键组成部分，对全球农业特别有价值。在全球范围内，根瘤菌和豆类之间的固氮共生体是农业系统氮输入的主要来源，并且许多豆类物种，如豌豆、小扁豆、大豆和鹰嘴豆是重要的粮食作物。根瘤菌与豆科植物的相互作用已被广泛研究，但这一过程是复杂的，需要进一步的基础研究才能充分认识到这一复杂性。根瘤菌诱导豆科植物根瘤的形成，在这些根瘤中，细菌将大气中的氮转化为植物可利用的形式。最近的微阵列基因表达和蛋白质组学研究清楚地证明了根瘤菌分化为共生体细胞（类菌体）时发生的戏剧性转化。然而，调节类杆菌分化的机制，特别是在分化过程中基因表达的下调，在很大程度上是未知的。我的研究计划的长期目标是使用遗传学为基础的方法来发现未知的调控途径，控制根瘤菌类杆菌的发展，并确定新的类杆菌发展所需的基因。更具体地说，拟议的研究将确定在类杆菌发育过程中控制与细胞分裂，运动和外膜蛋白相关的基因下调的调节因子和信号。蛋白酶作为类菌体发育调节因子的作用也将在本提案中进行研究。这项研究的结果可能适用于其他细菌-宿主关系，特别是α-变形菌纲内的致病相互作用，可能会发现调节致病过程的新机制。