Genetic, Biochemical, and Physiological Characterization of the Plant Symbionts Sinorhizobium meliloti and Rhizobium leguminosarum

根瘤菌是一种革兰氏阴性土壤细菌，它与豆类植物相互作用，在豆类植物的根部产生固氮根瘤，从而使植物能够在缺氮条件下生存。对苜蓿中华根瘤菌的基因组进行了测序，并将其作为研究植物-微生物相互作用的模式菌。尽管早期结瘤所涉及的信号的遗传学和生物化学研究进展很快，但人们对新陈代谢如何影响植物-细菌相互作用的早期阶段知之甚少。无法利用豆科植物根部常见的糖会影响根瘤菌与植物的相互作用。不能利用植物细胞壁的一种成分鼠李糖产生的菌株对根瘤占有率没有竞争力，而不能利用半乳糖的菌株产生对根瘤占有率更具竞争力的菌株。

Rhizobium is a Gram-negative soil bacterium that interacts with legumes to produce nitrogen fixing nodules on the roots of legumes thus allowing the plant to live under nitrogen deficient regimes. The genome of Sinorhizobium meliloti is sequenced and has been adopted as a model bacterium in which to study plant-microbe interactions. Although the genetics and biochemistry of the signaling involved during early nodulation are rapidly progressing, comparatively little is understood about how metabolism affects these early stages of plant-bacteria interaction. The inability to utilize sugars that are commonly found around the roots of legume plants can affect how the rhizobia interact with the plant. The inability to utilize rhamnose, a constituent of the plant cell wall, yields a strain that is uncompetitive for nodule occupancy, whereas a strain unable to use galactose gives rise to a strain that is more competitive for nodule occupancy.