Studies on the physiological mechanisms of preference of Rj2Rj4-harboring soybeans for rhizobial strains and the application to improvement of inoculation method

为了提高接种根瘤菌的根瘤占有率，提高根瘤菌的固氮能力，研究了携带结瘤限制基因(Rj)的大豆品种对根瘤菌菌株的优先利用能力。从大豆IAC-2(Rj2Rj3)与Hill(Rj4)杂交后代中分离到Rj2Rj4-基因型，经鉴定为Rj2Rj3Rj4-型，因此认为Rj3与Rj2位于同一染色体上。从大田大豆中分离到根瘤菌Rj2Rj3Rj4，分成两类，一类产生IAA，使培养基碱化；另一类不产生IAA，碱化培养基但酸化2周。然后，根据菌落特征将这些菌株分为9个类型，并考察了分离到的根瘤菌的类型与大豆RJ-基因之间的关系，但这种相关性没有被认识到。在盆栽和田间试验中，Rj2Rj4-型大豆对USDA110血清型的根瘤菌表现出更高的选择性，其中Hup阳性菌株的比例较高。对田间生长的不同RJ-型菌株的限制性片段长度多态性(RFLP)进行了检测，但没有发现RFLP与分离到根瘤菌的大豆基因型之间的相关性。但根据结瘤类型或生理特性划分的某些大豆群体具有根瘤菌的特征条带。这一结果表明，对日本双胞菌基因组结构的分析有助于阐明携带RJ基因的大豆对根瘤菌菌株的偏好的生理机制。

In order to improve the nodule occupancy of inoculant rhizobia and to increase nitrogen fixation, utility of preferential ability of soybean cultivars harboring nodulation restricting genes (Rj) for rhizobial strains was examined.The Rj2Rj4-genotypes of soybeans were isolated from of progenies of the cross of soybean IAC-2 (Rj2Rj3) and Hill (Rj4) and were demonstrated to be Rj2Rj3Rj4-genotypes, therefore, Rj3 was considered to locate in the same chromosome as Rj2. Nodule bacteria were isolated from Rj2Rj3Rj4-soybeans in field were classified into 2 categories, one of them produced IAA and alkalized the culture medium and the other did not produce IAA and alkalized the medium but had acidified it ce 2 weeks. Then, the isolates were separated into 9 types based on their features of colonies and examined the relation between the types and Rj-genotypes of the soybeans, from which the rhizobia were isolated, however, the correlation did not recognized. In pot and field experiments, the Rj2Rj4-genotypes of soybean were showed to prefer more actively USDA110 serotype of rhizobia, which included Hup positive strains at high rates more than the other genotypes.The restriction fragment length polymorphism (RFLP) of isolates from various Rj-genotypes grown in fields was examined, however, the correlation between RFLPs and the genotypes of soybean, from which rhizobia were isolated, could not be found. But some groups of soybean classified by nodulation-type or physiological features were showed to have the characteristic bands of P.These results indicated that the structure analysis of the B.japonicum gemome was useful for clarification of the physiological mechanism of preferences of soybean harboring Rj-genes for rhizobial strains.