Dr. Matthew T. Agler (University Jena) (online)
As guest of the CRC 1182
Dr. Matthew T. Agler
Pathogens are highly efficient (and apparently typical) early colonizers of Arabidopsis thaliana. Should we reconsider our plans for them?
Microbial colonizers play important roles in practically every aspect of plant life. Leaves are highly sensitive plant organs that are also home to diverse microbial communities. Since plant immune systems and microbe-microbe interactions play large roles in shaping leaf microbiota, it is often assumed that we should try to leverage these tools to completely exclude potential pathogens. In wild plants, however, potential pathogens can readily be recovered from apparently healthy leaves and we know little about why this is or its importance for plants. In controlled experiments we found that when inoculation was delayed beyond seed germination, plant microbiomes and phenotypes were significantly changed, underscoring the importance of early colonization. Using single-bacterial cell inoculation of germinating seeds, we found that both commensal and parasitic bacteria can be competitive early leaf colonizers, but the most efficient are potentially devastating pathogens including Pseudomonas syringae and Xanthomonas campestris. Despite their pathogenicity, when added to soil as inoculum for germinating seeds, these seem to contribute to consistently healthy, robust plants, possibly suggesting dual roles in natural systems. Whereas commensal early colonizers associate differentially with diverse A. thaliana genotypes, “pathogens” colonize consistently and mostly independent of host genotype. This is in part because they are well-adapted to resist host defense chemistry. Thus, we argue that understanding alternative ecological roles of potential pathogens in plants will help in our efforts to design microbiomes that consistently benefit plants.
Register in advance for this Zoom meeting:
October 19th, 2021