The molecular basis of efficient interspecies competition during host plant colonization
J. RUHE (1), M. Müller (1), M. Agler (1), I. Finkemeier (2), S. Ryazanov (3), C. Griesinger (3), E. Kemen (1) (1) Max Planck Institute for Plant Breeding Research, Germany; (2) Institute for Plant Biology and Biotechnology, University of Muenster, Germany; (3) Max Planck Institute for Biophysical Chemistry, Germany

The diversity of microbial phyllosphere communities is significantly influenced by biotic factors. Within microbial community networks few “hub” microbes show disproportionally high levels of connectivity and the ability to reshape communities. To elucidate how hub microbes influence bacterial growth in a community context we studied the endophytic hub genus Albugo during different stages of infection on Arabidopsis thaliana. During early Albugo infection phases, stomatal responses in various plant mutant backgrounds revealed LOX-dependent stomatal closure. This Albugo-induced stomatal closure was not triggered by microbe-associated molecular patterns, but by an Albugo-produced fatty acid and resulted in significantly reduced growth of bacterial endophytes. During later stages of infection, shotgun proteomics of apoplastic fluids showed high concentrations of Albugo-secreted amyloid proteins, which accumulated at hyphal cell walls and were important for Albugo fitness. Furthermore, they were at least partially responsible for antimicrobial effects in Albugo-infected apoplast. We suggest that via induced stomatal closing the microbial hub Albugo limits the entry of potential competitors or even destroyers of its ecological niche. Once its lifestyle is established, direct Albugo-endophytes interactions limit bacterial growth in the apoplast. Uncovering these microbial selection mechanisms opens great chances to specifically influence microbial communities for crop protection.

Abstract Number: P3-75
Session Type: Poster