Outer membrane vesicles (OMVs), pinching off the cell-wall of Gram-negative bacteria, are involved in multiple processes including response to stresses, delivery of virulence factors, host immune modulation and more. Nevertheless, very few reports studied the role OMVs play during plant-microbe interactions. We recently demonstrated that Arabidopsis up-regulates specific immune markers in response to OMVs purified from Xanthomonas campestris pv. campestris (Xcc) and other bacterial pathogens. To better understand the broader response of Arabidopsis to OMV challenge, we conducted RNA-seq analysis and plant pretreatment assays. Arabidopsis seedlings challenged with Xcc OMVs induced the expression of a large suite of immune-related genes including surface-bound and intracellular immune receptors. This transcriptional shift towards immune activation, primed Arabidopsis plants, rendering them more resistant to subsequent infection. OMVs proteomic analyses of four different plant-associated bacteria revealed a variety of potential MAMPs, virulence factors and secreted enzymes that may play a role during plant colonization. Interestingly, grouping OMV proteins by their predicted cell compartment localizations revealed variations among the different bacteria, hinting on a slightly different secretion mechanism or perhaps a different protein sorting process. Further research is underway to explore the full spectrum of OMV functions during plant colonization.

​The biennial Congress on Molecular Plant-Microbe Interactions is a major function of IS-MPMI. This is an excellent opportunity to learn and share with all of the international members. The Congress has been held throughout the world, with locations varying from, most recently, U.S., Greece, Japan, Italy, Mexico, and Russia. Always well attended, the Congress speaks to the vitality of IS-MPMI and the important role this meeting plays in helping facilitate the important work of our members. ​