摘要
对三叶草根瘤菌Rhizobium trifolii野生型菌株ANU843及其转座子Tn5诱导的突变株nod258和nod261的侵染和结瘤能力进行了比较。Ⅲ区结瘤基因nodFE的突变株(nod258)能在地三叶草(Subterranean clover)上正常侵染和结瘤,但瘤数比ANU843所诱导的略有减少。而Ⅱ区结瘤基因nodIJ的突变抹(nod261)却表现侵染力减弱,诱导无效瘤和瘤数大大减少。显微镜观察和超微结构研究表明菌株ANU843在接种后24h侵染已经从植物根毛开始,48h侵染线(infection thread)发展到表皮细胞并开始分支,接种后72h侵染线进一步发展,深入皮层细胞,这时皮层细胞已经大量分裂增生,形成瘤的分生组织。成熟的瘤细胞内充满了类菌体。而nod261突变株侵染植物比ANU843推迟了24h,侵染线的发展受阻碍,接种后72h侵染线仍然停留在根毛细胞中。nod261突变株所诱导的瘤细胞内没有或仅有个别类菌体,是无效瘤。这表明结瘤基因nodIJ与侵染线的正常形成和发展密切相关。
The capability of infection and nodulation by Tn5 induced mutants nod 258 and nod 261 was compared to the wild-type Rhizobium trifolii strain ANU 843. The mutant strain of nodulation genes(nod FE)located in region Ⅲ (nod 258)induced normal infection and nodulation on subterranean clovers with nodule number slightly reduced in comparison with strain ANU 843. However nod IJ mutant (nod 261)appeared a poor infective ability and induced non-effective nodule with the nodule number markedly reduced.Observation by microscopy and ultrastructure study indicated that infection induced by ANU 843 had already started in root hair cell at 24h after inoculation, infection threads developed to epidermal cell and ramified at 48h, by 72h infection threads futher developed to many cortical cells, intensive cortical cell divisions had already occured and nodule meristem formed. The central tissues of mature nodule induced by strain ANU 843 were filled with numbers of bacteroid(nitrogen fixation occurred there). In contrast, infection response induced by nod 261 mutant showed a 24h delay when compared to strain ANU 843. Infection threads aborted and still limited in root hair even 72h after inoculation. The central tissues of nodule induced by nod261 with few bacteroid and appear(?)d no effective. This indicated that nodlJ genes play an important role in infection thread formation and development.
出处
《生物工程学报》
CAS
CSCD
北大核心
1990年第3期212-217,共6页
Chinese Journal of Biotechnology
关键词
转座子诱变
三叶草根瘤菌
侵染
Transposon mutagenesis
spot inoculation
infection
nodulation
ultrastiucture
