Strains HH103 and NGR234 Form Nitrogen Fixing Nodules With Diverse Wild Soybeans () From Central China but Are Ineffective on Northern China Accessions.

indigenous populations are prevalent in provinces of Central China whereas species (, , , and others) are more abundant in northern and southern provinces. The symbiotic properties of different soybean rhizobia have been investigated with 40 different wild soybean () accessions from China, Japan, Russia, and South Korea. Bradyrhizobial strains nodulated all the wild soybeans tested, albeit efficiency of nitrogen fixation varied considerably among accessions. The symbiotic capacity of HH103 with wild soybeans from Central China was clearly better than with the accessions found elsewhere. NGR234, the rhizobial strain showing the broadest host range ever described, also formed nitrogen-fixing nodules with different accessions from Central China. To our knowledge, this is the first report describing an effective symbiosis between NGR234 and . Mobilization of the HH103 symbiotic plasmid to a NGR234 pSym-cured derivative (strain NGR234C) yielded transconjugants that formed ineffective nodules with cv. Williams 82 and accession CH4. By contrast, transfer of the symbiotic plasmid pNGR234a to a pSymcured derivative of USDA193 generated transconjugants that effectively nodulated accession CH4 but failed to nodulate with cv. Williams 82. These results indicate that intra-specific transference of the symbiotic plasmids generates new strains with unpredictable symbiotic properties, probably due to the occurrence of new combinations of symbiotic signals.