Phylogenetic Analysis of Soybean-Nodulating Rhizobia Isolated from Alkaline Soils in Vietnam |
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Authors: | Yuichi Saeki Ai Kaneko Toshiaki Hara Koutaro Suzuki Takeo Yamakawa Minh Thi Nguyen Yoshitaka Nagatomo Shoichiro Akao |
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Institution: | Department of Biochemistry and Applied Biosciences, Faculty of Agriculture, Miyazaki University, Miyazaki, 889–2192 Japan;Department of Plant Resources, Faculty of Agriculture, Kyushu University, Fukuoka, 812–8581 Japan;Department of Agrochemistry and Microbiology, Faculty of Land and Environment, Hanoi Agricultural University, Gia Lam, Hanoi, Vietnam |
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Abstract: | In order to analyze the phylogeny of soybean-nodulating bacteria in alkaline soils in Vietnam, indigenous soybean-nodulating bacteria were isolated from root nodules by cultivating three kinds of Rj -soybean cultivars on two alkaline soils in Vietnam. The 120 isolates were classified into two major genera of soybean-nodulating rhizobia, namely Bradyrhizobium and Sinorhizobium genera, based on a growth analysis on medium and PCR-RFLP analyses of 16S rDNA and of the 16S–23S rDNA internal transcribed spacer (ITS) region. Most of the isolates of B. japonicum were extra-slow-growing and their ITS types were similar to that of B. japonicum USDA 135. They were not isolated from the soybean cultivar CNS used as Rj2Rj3 genotype. Isolates of Sinorhizobium were divided into two groups, S. fredii and S. sp., based on a PCR-RFLP analysis of 16S rDNA. Furthermore, PCR-RFLP analysis of the 16S–23S rDNA ITS region enabled to separate them into five types, three ITS types associated with S. fredii and two with S. sp. Sinorhizobium was frequently isolated from the three soybean cultivars on two soils. From the isolate ratio, it was suggested that B. japonicum strains similar to B. japonicum USDA 135 and S. fredii predominated in the alkaline soils of Vietnam. Additionally, our findings indicated that the Rj -genotypes affected not only the compatibility, but also the preference for nodulation between the host soybean and rhizobia. |
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Keywords: | alkaline soil Bradyrhizobium Rj-soybean Sinorhizobium Vietnam |
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