Finan T M, Hirsch A M, Leigh J A, Johansen E, Kuldau G A, Deegan S, Walker G C, Signer E R
Cell. 1985 Apr;40(4):869-77. doi: 10.1016/0092-8674(85)90346-0.
Spontaneous mutants at a new symbiotic locus in Rhizobium meliloti SU47 are resistant to several phages and are conditionally insensitive to a monoclonal antibody to the bacterial surface, apparently because they are deficient in a wild-type exopolysaccharide. On alfalfa, the mutants do not curl root hairs, but penetrate the epidermis directly, forming nodules that contain no visible infection threads or "bacteroids," have a few bacteria in superficial intercellular spaces only and not within the nodule cells, and fail to fix nitrogen (Fix-). Evidently, infection threads are not essential for cell proliferation and nodule formation, which are here induced by a bacterial signal at a distance and uncoupled from the bacterial differentiation that normally goes on as well.
苜蓿中华根瘤菌SU47一个新的共生位点上的自发突变体对几种噬菌体具有抗性，并且对一种针对细菌表面的单克隆抗体有条件不敏感，这显然是因为它们缺乏野生型胞外多糖。在苜蓿上，这些突变体不会使根毛卷曲，而是直接穿透表皮，形成不含可见感染丝或“类菌体”的根瘤，根瘤中仅在表面细胞间隙中有少量细菌，而在根瘤细胞内没有，并且不能固氮（Fix-）。显然，感染丝对于细胞增殖和根瘤形成不是必需的，在这里细胞增殖和根瘤形成是由远处的细菌信号诱导的，并且与正常情况下同时发生的细菌分化解偶联。
