Salim Bourras

THE PLANT IMMUNITY GROUP

THE SLU PLANT CLINIC LABORATORY

BASIC RESEARCH

PLANT-PATHOGEN-MICROBIOME INTERACTIONS 

The plant rhizosphere and phyllosphere are taxonomically rich habitats for a variety of microorganisms competing for the same limited resources. Our first line of research aims at understanding the molecular mechanisms that pathogens have evolved to outcompete the local microbiome and persist in nature. The first answer to this question can be traced back to Alexander Fleming’s discovery of Benzylpenicillin (Penicillin), a substance produced by the Ascomycete fungus Penicillium chrysogenum primarily employed to outcompete bacteria for food sources. Considering the ecological role of antibiotics, our work and the work of others suggest there is a much larger diversity of antimicrobial agents and strategies employed by plants and fungi to interact with their environment and other organisms. Our work focuses on the antimicrobial interactome regulating plant-pathogen-microbiome interactions, and the specific contribution of cross-kingdom molecular mobility provided by small RNAs, effectors proteins, and antimicrobial proteins, to the establishment and resilience of ‘healthy’ plant populations.

PLANT IMMUNITY AND RESISTANCE TRADEOFFS

The plant immune system is the master regulator of both beneficial and pathogenic plant-microbe interactions. Our second line of research aims at understanding the contribution of Plant-Microbiome and Plant-Plant interactions to the regulation of non-host resistance (NHR) and multi-pathogen resistance (MDR). Immunity is costly. When the immune system is activated, plants must make lifesaving decisions as to what resistance gene goes first (timing and prioritization), where it must be expressed (tissue specificity), how long and how strong it is must expressed (energy cost). An additional layer of complexity is provided by the fact that resistance to different, simultaneously occurring diseases might require diametrically opposed immune responses thus leading to important tradeoffs. There is increasing evidence suggesting that pathogens have evolved the capacity to highjack these tradeoffs, while in other cases, interference between host’s immune receptors has been reported. Our works aims at uncovering novel mechanisms in plant immunity and diseases resistance based on the study of plant immune receptors, trade-off mitigation traits, and plant-plant interactions.