nolA基因在费氏中华根瘤菌中的验证及其对结瘤的影响

根据已公布的大豆慢生根瘤菌(Bradyrhizobium japonicum)nolA基因序列（AF322013)，设计了一对保守区的特异性引物和1对非保守区的全长基因引物，通过PCR扩增发现在个别费氏中华根瘤菌(Sinorhizobium fredii)中也存在nolA基因。进一步的结瘤抑制试验结果表明：含有nolA基因的费氏中华根瘤菌也有种群密度依赖调节方式的结瘤抑制现象，本结果对提高商品化根瘤菌剂的竞争结瘤能力具有重要的参考价值。

The Existing of nolA Gene in Sinorhizobium fredii HH21 and Its Inhibition Effect on Nodulation

A special pair of conservative primers and a pair of complete gene primers were designed based on the released nolA gene (GenBank number: AF322013) of Bradyrhizobium japonicum. PCR results showed that Sinorhizobium fredii strain HH21 contained nolA gene.Nodulation repression was also proved in Sinorhizobium fredii strain HH21 by both pot and test tube plant nodulation experiments.This character is triggered by the expression of nolA gene in Bradyrhizobium japonicum and controled by the approach of population density-dependent regulation. These results offer a hint to improve the competition ability for commercial rhizobia inoculant.