| Budget Amount *help |
¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000)
Fiscal Year 2012: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2011: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2010: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
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| Research Abstract |
We investigated the relationship between the genetic diversity of indigenous soybean-nodulating bradyrhizobia and their geographical distribution in the United States using nine soil isolates from eight states. The bradyrhizobia were inoculated on three soybean Rj genotypes (non-Rj, Rj2Rj3, and Rj4). We analyzed their genetic diversity and community structure by means of restriction-fragment length polymorphisms of PCR amplicon to target the 16S-23S rRNA gene internal transcribed spacer region, using 11 USDA Bradyrhizobium strains as reference strains. We also performed diversity analysis, multi-dimensional scaling analysis based on the Bray-Curtis index, and polar ordination analysis to describe the structure and geographical distribution of the soybean-nodulating bradyrhizobial community. The major clusters were Bradyrhizobium japonicum Bj123, in the northern U.S., and Bradyrhizobium elkanii in the middle to southern regions. Dominance of bradyrhizobia in a community was generally larger for the cluster belonging to B. elkanii than for the cluster belonging to B. japonicum. The indigenous American soybean-nodulating bradyrhizobial community structure was strongly correlated with latitude. Our results suggest that this community varies geographically.
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