Effects of root exudates of Rj2Rj3- and Rj4-genotype soybeans on growth and chemotaxis of Bradyrhizobium japonicum |
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| Authors: | Yuichi Saeki Takeo Yamakawa Motoki Ikeda Junji Ishizuka |
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| Institution: | Department of Agricultural Chemistry , Faculty of Agriculture, Kyushu University , 46-02, Fukuoka , 812-81 , Japan |
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| Abstract: | Almost all of the soybean cultivars (Glycine max L. Merr.) form nodules on their roots by infection with Bradyrhizobium japonicum. However, it has been observed that the soybean cultivars harboring nodulation conditioning genes, for instance Rj 2, Rj 3, and Rj 4, do not form effective nodules with some strains of B. japonicum. Ishizuka et al. (1991b) classified the rhizobia isolated from field-grown soybeans into nodulation-types A, B, and C based on the compatibility with these Rj-soybean cultivars. Nodulation-type B is incompatible with Rj 2 Rj 3-cultivars and type C is incompatible with Rj 4-cultivars. Nodulation-type A rhizobia are compatible with both Rj 2 Rj 3 - and Rj 4-cultivars. Furthermore, the Rj-cultivars were found to prefer appropriate nodulation-type rhizobia for nodulation, that is, non-Rj-, Rj 2 Rj 3 -, and Rj 4-cultivars prefer nodulation-types A, C, and B rhizobia, respectively (Ishizuka et al. 1991a). In the present study, in order to examine the mechanisms of preference of Rj-cultivars for rhizobial strains for nodulation, root exudates from Rj-cultivars were examined for their effects on the growth rate and chemotaxis of various types of B. japonicum strains. |
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| Keywords: | B japonicum chemotaxis nodulation -type Rj-genotype root exudate |
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