Differential Expression of Paraburkholderia phymatum Type VI Secretion Systems (T6SS) Suggests a Role of T6SS-b in Early Symbiotic Interaction

Paraburkholderia phymatum STM815, a rhizobial strain of the Burkholderiaceae family, is able to nodulate broad range legumes including agriculturally important Phaseolus vulgaris (common bean). P. harbors two type VI Secretion Systems (T6SS-b and T6SS-3) in its genome that contribute high interbacterial competitiveness vitro infecting roots several legumes. In this study, we show T6SS-b found genomes soil-dwelling plant symbionts expression induced by presence citrate higher at 20/28°C compared 37°C. Conversely, T6SS-3 shows homologies T6SS clusters pathogenic Burkholderia strains, more prominently expressed with succinate during stationary phase addition, was activated germinated seeds as well Mimosa pudica root nodules. Phenotypic analysis selected deletion mutant strains suggested role motility but not later stages interaction contrast, affected any free-living symbiotic phenotypes examined. Thus, potentially for early infection step symbiosis