|Van Berkum, Peter|
Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/2001
Publication Date: N/A
Interpretive Summary: Bean is an important grain legume. Because it is a legume it benefits from biological nitrogen fixation through a symbiosis with soil bacteria referred to as rhizobia. In agriculture, the benefit is in the form of enhanced efficiency of crop production. Management of biological nitrogen fixation involves the inoculation of the appropriate bacterial cultures at the time of sowing. These bacterial cultures are available to the farmer as inoculants manufactured by industry. The problem is that many different bacteria are available for bean, but comprehensive investigations for differences involve many sophisticated methods. Here we report that the analysis of low molecular weight ribonucleic acids is useful as a diagnostic tool to identify newly isolated symbionts of bean. Our results will be useful to scientists who are interested in evolutionary biology, taxonomy and strain identification.
Technical Abstract: Common bean is nodulated by genetically heterogeneous rhizobia that are present in widely separate geographic locations. A rapid method for the presumptive phylogenetic placement of newly isolated cultures from bean nodules is not available. Therefore, we examined an approach based on the analysis of low molecular weight (LMW) RNA molecules using Staircase electrophoresis. We obtained profiles of the type strains of the proposed rhizobial species that nodulate bean and also of other isolates assigned to these different species. The profiles we obtained for strains placed within the proposed species were identical even though the profiles across species varied. We also examined bean isolates obtained from two different regions in Spain. Based on our results we demonstrated that bean isolates from a soil in Andalucia shared profiles with R. etli, R. gallicum, R. giardinii, R. leguminosarum bv. trifolii and Sinorhizobium fredii. Bean isolates originating from a soil in Leon had profiles characteristic of R. leguminosarum bv. viciae and R. leguminosarum bv. trifolii.