根瘤菌结瘤基因研究的新进展

简要综述了目前根瘤菌结癌基因研究的3个热点方向，即结瘤因子、nodlD基因的调控和结瘤基因系统发育分析的新进展。结瘤因子的骨架核心是结瘤基因中的共同性基因nodABC表达的产物，宿主专一性基因则进行骨架结构的修饰，所形成的特异性结瘤因子是根瘤苗宿主范围的主要决定因素。结瘤调控基因nodD的作用方式与其存在的拷贝数目和产物NodD蛋白活性有关，同时NodD的敏感性还影响到根瘤菌的宿主范围。结瘤基因的系统发育揭示出根瘤菌宿主范围与共同性结瘤基因间比其它基荫的相关性更高。结瘤基因与豆科宿主之间存在一定的共进化关系。

NOVEL ADVANCES ON NODULATION GENE STUDY OF NODULE BACTERIA

Three hot research directions of rhizobial nodulation genes, i. e. novel advances on Nod factor, regulation of nod D, and phylogenic analysis of nodulation genes were summarized in this paper. The common nod A B C genes are responsible for the kernel of backbone structure in Nod factor synthesis and the hostspecific nod genes add particular decorations to the backbone. The host-range of any rhizobial species is largely detedrined by the specificity of Nod Factor it produces. The effect mode of regulatory nod D is related to the copy numbers of nod D genes and the activity of Nod D protein. At the same time, the sensitivity of Nod D affects the specificity of host range of rhizobia. The phylogenetic studies on nod genes have promulgated that the host range of rhizobia appeared to have a higher interrelationship to the common nod genes than other genes. The occurrence of a certain co-evolution relation has been found between the nodulation genes and the host plants.