Ca2+-dependent nanodomain enrichment is crucial for the perception of bacterial outer membrane vesicles in plants

Outer membrane vesicles (OMVs) of Gram-negative bacteria play a crucial role in virulence, communication, and survival. In plants, OMVs induce an immune response. Also, OMVs have been utilised to prime plants against the pathogen. However, a thorough understanding of plant-bacterial interaction via OMVs is still less explored. Our research aims to comprehend the underlying events during the perception of Xanthomonas oryzae pv. oryzae (Xoo)-OMVs by the host plant, rice (Oryza sativa subsp. indica). We have identified that Xoo-OMVs contain virulence-associated proteins, MAMPs, cell wall-degrading enzymes, nutrient-acquisition proteins, and proteins to defend the bacteria against the host immune response. We establish that Xoo-OMVs can elevate cellular calcium (Ca2+) concentration in rice. We report that this early Ca2+ signal is essential for nanodomain enrichment in the rice plasma membrane after exposure to Xoo-OMVs. We have observed that Xoo-OMVs get incorporated into the plasma membrane of rice. Our results assert that the insertion of Xoo-OMVs into the plasma membrane of rice is also a Ca2+-dependent process. Moreover, we establish that with the chelation of Ca2+, the resistant rice seedlings exhibit a weakened immune response against Xoo-OMVs. Taken together, our study reveals the early events of Xoo-OMV perception by rice via the Ca2+ signal.