AUTHOR=Lardi Martina , de Campos Samanta Bolzan , Purtschert Gabriela , Eberl Leo , Pessi Gabriella 

TITLE=Competition Experiments for Legume Infection Identify Burkholderia phymatum as a Highly Competitive β-Rhizobium

JOURNAL=Frontiers in Microbiology

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2017.01527

DOI=10.3389/fmicb.2017.01527

ISSN=1664-302X

ABSTRACT=<p>Members of the genus <italic>Burkholderia</italic> (β-proteobacteria) have only recently been shown to be able to establish a nitrogen-fixing symbiosis with several legumes, which is why they are also referred to as β-rhizobia. Therefore, very little is known about the competitiveness of these species to nodulate different legume host plants. In this study, we tested the competitiveness of several <italic>Burkholderia</italic> type strains (<italic>B. diazotrophica</italic>, <italic>B. mimosarum</italic>, <italic>B. phymatum</italic>, <italic>B. sabiae</italic>, <italic>B. symbiotica</italic> and <italic>B. tuberum</italic>) to nodulate four legumes (<italic>Phaseolus vulgaris</italic>, <italic>Macroptilium atropurpureum</italic>, <italic>Vigna unguiculata</italic> and <italic>Mimosa pudica</italic>) under our closely defined growth conditions. The assessment of nodule occupancy of these species on different legume host plants revealed that <italic>B. phymatum</italic> was the most competitive strain in the three papilionoid legumes (bean, cowpea and siratro), while <italic>B. mimosarum</italic> outcompeted the other strains in mimosa. The analysis of phenotypes known to play a role in nodulation competitiveness (motility, exopolysaccharide production) and additional <italic>in vitro</italic> competition assays among β-rhizobial strains suggested that <italic>B. phymatum</italic> has the potential to be a very competitive legume symbiont.</p>