费氏中华根瘤菌共生质粒缺失对结瘤和固氮能力的影响

费氏中华根瘤菌（Sinorhizobium fredii)HN01在大豆上的结瘤表现为非品种专一性，其共生质粒pSymHN01b在诱动转入另一非品种专一性结瘤菌株WWG18SR后，获得的转移接合子WWG18SRN1中的pSymHN01b缺失约40b。盆栽结瘤试验证明，pSymHN01b的缺失导致WWG18SRN1由非品种结瘤菌株转变为大豆品种专一性结瘤菌株，并失去了在所有供试的大豆品种上固氮的能力。在获得了完整的pSymHN01b的转移接合子WWG18SRN2存在时，WWG18SRN1在黑农33上的结瘤受到抑制。

Deletion in the Symbiotic Plasmids of Sinorhizobium fredii HN01 Effect on the Function of Nodulation and Fixation

Sinorhizobium fredii HN01 is a cultivar non-specific nodulation strain on soybean. The symbiotic plasmid pSymHNOlb of HN01 was deleted about 40 kb when it mobilized into WWG18SR which is another cultivar non-specific strain of S. fredii. The pot plant test indicated that the deletion of pSymHNOlb in the transconjugation WWG18SRN1 caused the alternation of host range of soybean culti-vars and the losing of the ability of fixing nitrogen on all tested soybean cultivars and G. soja. Nodulation of soybean by WWG18SRN1 was subject to competitive nodulation blocked by the transconjugation of WWG18SRN2 and WWG18SR contains the whole pSymHNOlb.