AUTHOR=Temprano-Vera Francisco , Rodríguez-Navarro Dulce Nombre , Acosta-Jurado Sebastian , Perret Xavier , Fossou Romain K. , Navarro-Gómez Pilar , Zhen Tao , Yu Deshui , An Qi , Buendía-Clavería Ana Maria , Moreno Javier , López-Baena Francisco Javier , Ruiz-Sainz Jose Enrique , Vinardell Jose Maria 

TITLE=Sinorhizobium fredii Strains HH103 and NGR234 Form Nitrogen Fixing Nodules With Diverse Wild Soybeans (Glycine soja) From Central China but Are Ineffective on Northern China Accessions

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.02843

DOI=10.3389/fmicb.2018.02843

ISSN=1664-302X

ABSTRACT=<p><italic>Sinorhizobium fredii</italic> indigenous populations are prevalent in provinces of Central China whereas <italic>Bradyrhizobium</italic> species (<italic>Bradyrhizobium japonicum</italic>, <italic>B. diazoefficiens</italic>, <italic>B. elkanii</italic>, 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 (<italic>Glycine soja</italic>) 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 <italic>S. fredii</italic> HH103 with wild soybeans from Central China was clearly better than with the accessions found elsewhere. <italic>S. fredii</italic> NGR234, the rhizobial strain showing the broadest host range ever described, also formed nitrogen-fixing nodules with different <italic>G. soja</italic> accessions from Central China. To our knowledge, this is the first report describing an effective symbiosis between <italic>S. fredii</italic> NGR234 and <italic>G. soja</italic>. Mobilization of the <italic>S. fredii</italic> HH103 symbiotic plasmid to a NGR234 pSym-cured derivative (strain NGR234C) yielded transconjugants that formed ineffective nodules with <italic>G. max</italic> cv. Williams 82 and <italic>G. soja</italic> accession CH4. By contrast, transfer of the symbiotic plasmid pNGR234a to a pSym<sup>-</sup>cured derivative of <italic>S. fredii</italic> USDA193 generated transconjugants that effectively nodulated <italic>G. soja</italic> accession CH4 but failed to nodulate with <italic>G. max</italic> cv. Williams 82. These results indicate that intra-specific transference of the <italic>S. fredii</italic> symbiotic plasmids generates new strains with unpredictable symbiotic properties, probably due to the occurrence of new combinations of symbiotic signals.</p>