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对根瘤菌的占瘤率，提高固氮能力，研究了含根瘤菌结瘤限制基因（Rj）的大豆品种对根瘤菌的优先利用能力。从大豆IAC-2 （Rj2Rj3）和Hill （Rj4）杂交后代中分离到rj2rj4基因型，证实为rj2rj3rj4基因型，因此认为Rj3与Rj2位于同一染色体上。从田间rj2rj3rj4大豆中分离到的根瘤菌分为2类，一类产生IAA并碱化培养基，另一类不产生IAA并碱化培养基，但在2周内酸化培养基。然后，根据菌落特征将分离菌株分为9个类型，并分析了这些类型与大豆rj基因型之间的关系，从rj基因型中分离出根瘤菌，但相关性不确定。盆栽和田间试验结果表明，大豆rj2rj4基因型对USDA110血清型的根瘤菌活性更高，其中Hup阳性菌株的比例高于其他基因型。对大田栽培的不同rj基因型菌株的限制性片段长度多态性（RFLP）进行了检测，但未发现RFLP与分离根瘤菌的大豆基因型之间的相关性。但根据根瘤型或生理特征分类的大豆类群中，也存在p的特征带。这表明，对日本芽孢杆菌基因组结构的分析有助于阐明含有rj基因的大豆对根瘤菌偏好的生理机制。

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.