Soberón-Chávez G, Nájera R, Calva E, Fernández M
Centro de Investigación sobre Ingeniería Genética y Biotecnología, UNAM, Cuernavaca, Morelos, Mexico.
Mol Microbiol. 1991 Jan;5(1):89-95. doi: 10.1111/j.1365-2958.1991.tb01829.x.
Rhizobium leguminosarum biovar phaseoli CFN23 loses its ability to nodulate beans at a high frequency because of a deletion of part of its symbiotic (pSym) plasmid (Soberón-Chávez et al., 1986). We report here that at least 80 kb of pSym are deleted upon loss of the symbiotic phenotype; the deletion removes the nitrogenase structural nifHDK and the common nodABC genes. The size of the deleted pSym is not reduced, since it is accompanied by an amplification of other pSym plasmid sequences. This genetic rearrangement is similar to the deletion and amplification of yeast mitochondrial DNA leading to 'petite' mutations.
菜豆根瘤菌生物变种CFN23由于其共生（pSym）质粒的部分缺失而丧失了高频结瘤菜豆的能力（索贝龙 - 查韦斯等人，1986年）。我们在此报告，共生表型丧失时，至少80 kb的pSym会被删除；该缺失移除了固氮酶结构基因nifHDK和共同的结瘤基因nodABC。被删除的pSym的大小并未减小，因为它伴随着其他pSym质粒序列的扩增。这种基因重排类似于导致酵母线粒体DNA“小菌落”突变的缺失和扩增。
