【摘要】 用一种重现性好而较简便的方法,对国内的紫云英、豌豆、三叶草、大豆等快生型根瘤菌及根癌农杆菌共40多号菌进行了质粒分离,所得质粒图谱具有一定的菌株特异性。每株菌有1—3个质粒,其中至少有一个大质粒或巨大质粒。用质粒消除法获得失去结瘤(或致癌)能力的变异株,均缺少一个大质粒。快生型根瘤菌的结瘤基因定位在大质粒或巨大质粒上。用接合法将RP1::Tn501等质粒转入根瘤菌中,能诱动根瘤菌的结瘤基因转移给失去结瘤能力的变异株,可表达功能,质粒图谱也发生变化,与供体或受体都不同。更多还原

【Abstract】 Plasmids were isolated from morethan 40 strains of Rhizobiaceae, includingRhizobium astragalii, R. leguminosarum,R. trifolii, R. japonicum and Agrobacte-rium tumefaciens by a reproducible andconvenient method. The plasmid profileswas varied among these strains. Eachstrain tested contained 1--3 plasmids withmolecular sizes from 40 Md to 300 Md ex-cept the R. leguminosarum strain 2101which did not show any plasmid band onthe agarose gel electrophoresis. After plas-mid curing all of the Nod~- Rhizobium mu-tants and the avirulent mutants of A. tu-mefacicns lost a large plasmid. The IncP1 group plasmid RP1: :Tn501 can mobilize the nodulation determi-nant(s) from Nod~+ Fix~+ wild type R.as-tragalii strain to the Nod~- mutants of R.astragalii. The plasmid profiles of theNod~+ transconjugants were different fromthe donor- and the recipient- strains. Thepossibility for improving Rhizobium strai-ns by the plasmid transfer technique wasimplied.更多还原