Exploring the mechanisms of immunosuppression by the plant-beneficial rhizobacterium Pseudomonas capeferrum WCS358
K. YU (1), R. Berendsen (1), C. Pieterse (1), P. Bakker (1) (1) Plant-Microbe Interactions, Faculty of Science, Utrecht University, Netherlands

Efficient root colonization by specific beneficial microbes is a crucial step for the onset of induced systemic resistance (ISR). Innate immune responses are activated in roots by recognition of microbe-associated molecular patterns (MAMPs). Whereas beneficial microbes possess MAMPs similar to those of plant pathogens, this does not lead to massive activation of plant defenses by the beneficials. The ISR-eliciting model strain Pseudomonas capeferrum WCS358 (WCS358) suppressed root immune responses elicited by flg22, a peptide derived from the bacterial MAMP flagellin. It is hypothesized that suppression of immunity is required for successful root colonization, but the mechanisms remain elusive. We initiated a transposon mutant library screening of WCS358 to explore the strategies of root immunosuppression by beneficial microbes. Several putative mutants were isolated and characterized, and are tested for rhizosphere competence. These experiments provide a more comprehensive understanding about how beneficial microbes suppress root immune responses and its relevance for rhizosphere colonization.

Abstract Number: P9-327
Session Type: Poster