中文摘要：

Rhizobia 与主人荚交往导致修理氮的小瘤的形成，它在农业和生态学是很重要的。修理氮的小瘤的开发被主机植物和 rhizobial 共生者紧地调整。在我们的以前的工作，新 Sinorhizobium meliloti LysR 管理者基因(lsrB ) 被识别为苜蓿生节必要。然而，这基因怎么涉及苜蓿生节，还没被理解。这里，我们发现这基因与早熟的小瘤老朽和未成功的假细菌形成的预防被联系。异构的缺乏的苜蓿根小瘤被 lsrB (lsrB1-2 ) 的在里面框架删除异种导致，它类似于 plasmid 插入异种， lsrB1。不规则的老朽地区更早在假细菌区别阻止显微镜学观察在不同阶段被接近的这些小瘤出现了。有趣地，氧化爆炸在这些小瘤被观察由轻拍染色。lipopolysaccharide 核心基因(lpsCDE ) 的减少的表示相应地在这些小瘤被决定。S。meliloti lipopolysaccharide 为氧化爆炸或主人房间防卫的抑制被要求。这些调查结果示威 S。meliloti lsrB 基因被在主机房间压制氧化爆炸或防卫回答涉及苜蓿根小瘤开发和假细菌区别。

英文摘要：

Rhizobia interact with host legumes to induce the formation of nitrogen-fixing nodules, which is very important in agriculture and ecology. The development of nitrogen-fixing nodules is stringently regulated by host plants and rhizobial symbionts. In our pre- vious work, a new Sinorhizobium meliloti LysR regulator gene （lsrB） was identified to be essential for alfalfa nodulation. Howev- er, how this gene is involved in alfalfa nodulation was not yet understood. Here, we found that this gene was associated with pre- vention of premature nodule senescence and abortive bacteroid formation. Heterogeneous deficient alfalfa root nodules were in- duced by the in-frame deletion mutant of lsrB （lsrB1-2）, which was similar to the plasmid-insertion mutant, lsrB1. Irregular se- nescence zones earlier appeared in these nodules where bacteroid differentiation was blocked at different stages from microscopy observations, Interestingly, oxidative bursts were observed in these nodules by DAB staining. The decreased expression of lipo- polysaccharide core genes （lpsCDE） was correspondingly determined in these nodules. S. meliloti lipopolysaccharide is required for suppression of oxidative bursts or host cell defense. These findings demonstrate that the S. meliloti lsrB gene is involved in alfalfa root nodule development and bacteroid differentiation by suppressing oxidative bursts or defense responses in host cells.