Nitrogen-Fixing Symbiotic Paraburkholderia Species: Current Knowledge and Future Perspectives

A century after the discovery of rhizobia, first Beta-proteobacteria species (beta-rhizobia) were isolated from legume nodules in South Africa and America. Since then, numerous belonging to Burkholderiaceae family have been isolated. The presence a highly branching lineage nodulation genes beta-rhizobia suggests long symbiotic history. In this review, we focus on beta-rhizobial genus Paraburkholderia, which includes two main groups: American mimosoid-nodulating Paraburkholderia African predominantly papilionoid-nodulating Paraburkholderia. Here, discuss latest knowledge nitrogen-fixing symbionts each step symbiosis, their survival soil, through contact with legumes until formation an efficient symbiosis root nodules. Special attention is given strain P. phymatum STM815T that exhibits extraordinary features, such as ability to: (i) enter into more than 50 species, including agriculturally important common bean, (ii) outcompete other rhizobial for several legumes, (iii) endure stressful soil conditions (e.g., high salt concentration low pH) temperatures.