hide
Free keywords:
-
Abstract:
Microbes affect plant health, stress tolerance and life history. In different host populations, plants are colonized by distinct pathogenic and commensal microbiomes, but the factors driving intra and inter-geographic variation are largely unknown. I will present two studies that explore the abiotic and biotic factors that influence the composition of the phyllosphere of Arabidopsis thaliana populations, and specifically the abundance of the bacterial pathogen Pseudomonas syringae. In the first study, we characterize the distribution and evolution of Pseudomonas pathogens across A. thaliana populations in Southern Germany. In the second study, we measured the core leaf microbiome of A. thaliana in its native range, from almost 300 populations across Europe. In these studies we discovered marked, geography-dependent differences in microbiome composition within A. thaliana and between A. thaliana and other Brassicaceae. We find evidence that host plant genetics acts to maintain different strains of Pseudomonas within populations as well as is associated with microbiome compositional differences across Europe. We further find that microbiome composition is best predicted by drought-associated metrics that are well known to be a major selective agent on A. thaliana populations. The reproducible and predictable associations between specific microbes and water availability raise the possibility that drought not only directly shapes genetic variation in A. thaliana, but does so also indirectly through its effects on the leaf microbiome.
