Beta-rhizobial symbiosis: new insights from genome-wide transcriptome and proteome analysis
M. LARDI (1), Y. Liu (2), L. Eberl (2), G. Pessi (2) (1) University of Zurich, Switzerland; (2) University of Zurich, Switzerland

The Rhizobium-legume symbiosis is of major ecological and economic importance and accounts for a fourth of the total nitrogen fixed annually on earth. In addition to the well-investigated and phylogenetically diverse alpha-rhizobia, various beta-proteobacteria of the genera Cupriavidus and Burkholderia are also able to establish nitrogen-fixing symbiosis with legumes (beta-rhizobia). At present, very little is known about the molecular determinants underlying the successful symbiosis between legumes and beta-rhizobia. In this study, we use RNA-Sequencing and shotgun proteomics to investigate and compare the expression profiles of Burkholderia phymatum grown in free-living conditions and inside Phaseolus vulgaris root nodules. This first genome-wide expression study on beta-rhizobial root nodules confirmed that genes and proteins coding for known important symbiotic functions such as nitrogen fixation and hydrogenase were significantly up-regulated during symbiosis. In addition, genes coding for flagella and type IV secretion system showed decreased expression in nodules suggesting that these functions are not needed for life inside the plant. Currently, we are investigating several genes and proteins highly expressed and up-regulated in P. vulgaris root nodules for their potential role in symbiosis.

Abstract Number: P2-35
Session Type: Poster