Ca2+-Driven Nanodomain Enrichment And Plasma Membrane Proteome Remodelling Govern Plant Response To Bacterial Outer Membrane Vesicles

Abstract

Phytopathogenic outer membrane vesicles (OMVs) can elicit protective immune responses and can be utilised for crop protection. Xanthomonas oryzae pv. oryzae (Xoo), a Gram-negative bacterium that causes Bacterial Blight of rice, releases OMVs. However, the role of Xoo-OMVs in the Xoo-rice interaction remains unexplored. We investigated the early signalling events underlying the plant's response to Xoo-OMV to gain insight into plant-pathogen interactions. We observed that Xoo-OMVs trigger a rapid, unique Ca2+ signal in rice that is essential for evoking an immune response. By imaging and proteomic analysis of the rice plasma membrane (PM), we found that this Ca2+ signal is required for Xoo-OMV-induced nanodomain enrichment and aggregation of defence response-associated proteins in rice PM. The specific protein assembly in the PM helps the plant defend itself against Xoo. In the absence of the early Ca2+ signal, rice cannot respond effectively to Xoo-OMVs, resulting in a compromised immune response. Collectively, our study shows that rice responds to Xoo-OMVs via Ca2+-signal-induced nanodomain assembly and protein reorganisation at the PM, preparing the plant for an imminent pathogen invasion.