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首页> 外文期刊>Journal of bacteriology >Nitrogen-fixing nodules induced by Agrobacterium tumefaciens harboring Rhizobium phaseoli plasmids.
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Nitrogen-fixing nodules induced by Agrobacterium tumefaciens harboring Rhizobium phaseoli plasmids.

机译：由根癌农杆菌携带菜豆根瘤菌质粒诱导的固氮根瘤。

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Rhizobium phaseoli CFN299 forms nitrogen-fixing nodules in Phaseolus vulgaris (bean) and in Leucaena esculenta. It has three plasmids of 185, 225, and 410 kilobases. The 410-kilobase plasmid contains the nitrogenase structural genes. We have transferred these plasmids to the plasmid-free strain Agrobacterium tumefaciens GMI9023. Transconjugants containing different combinations of the R. phaseoli plasmids were obtained, and they were exhaustively purified before nodulation was assayed. Only transconjugants harboring the 410-kilobase plasmid nodulate P. vulgaris and L. esculenta. Nodules formed by all such transconjugants are able to reduce acetylene. Transconjugants containing the whole set of plasmids from CFN299 nodulate better and fix more nitrogen than the transconjugants carrying only the Sym plasmid. Microscopic analysis of nodules induced by A. tumefaciens transconjugants reveals infected cells and vascular bundles. None of the A. tumefaciens transconjugants, not even the one with the whole set of plasmids from CFN299, behaves in symbiosis like the original R. phaseoli strain; the transconjugants produce fewer nodules and have lower acetylene reduction (25% as compared to the original R. phaseoli strain) and more amyloplasts per nodule. More than 2,000 bacterial isolates from nodules of P. vulgaris and L. esculenta formed by the transconjugants were analyzed by different criteria. Not a single rhizobium could be detected. Our results show that R. phaseoli plasmids may be expressed in the A. tumefaciens background and direct the formation of effective, differentiated nodules.
机译：菜豆根瘤菌CFN299在菜豆（豆）和菜豆中形成固氮根瘤。它具有三个分别为185、225和410千碱基的质粒。 410碱基碱基的质粒包含固氮酶结构基因。我们已将这些质粒转移到无质粒的根癌农杆菌GMI9023中。获得了包含菜豆R.质粒不同组合的转导结合体，并在分析结节之前对其进行了彻底纯化。只有带有410碱基碱基质粒的转导结合体会结节寻常性假单胞菌和食用菌。由所有这些超共轭物形成的结节能够还原乙炔。与仅携带Sym质粒的反式结合物相比，含有CFN299整套质粒的反式结合物的结瘤效果更好，固定的氮含量更高。根癌农杆菌转导结合物引起的结节的显微镜分析揭示了感染的细胞和血管束。没有一种根癌农杆菌转导结合体，甚至没有带有来自CFN299的整套质粒的转导结合体，都像原始的R. phaseoli菌株那样在共生中起作用。转偶合剂产生的结节更少，乙炔还原率较低（与原始的菜豆红霉菌菌株相比降低25％），每个结节的淀粉质体更多。通过不同的标准分析了由转导结合剂形成的来自寻常型假单胞菌和七叶草的结核的2,000多种细菌分离株。不能检测到单个根瘤菌。我们的结果表明，菜豆R.质粒可能在根癌农杆菌的背景中表达，并指导有效，分化结节的形成。

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