Messenger and message: Uncovering the roles, rhythm and regulation of extracellular vesicles in plant biotic interactions.

Extracellular vesicles (EVs) are membrane-delimited nanoparticles found in every kingdom of life and are known to mediate cell-cell communication in animal systems through the trafficking of proteins and nucleic acids. Research into plant and microbial EVs suggests that these have similar transport capacity, and moreover are able to mediate signalling not only within an organism but also between organisms, acting between plants and their microbial partners in cross-kingdom signalling. Here, we review recent research exploring the roles of these EVs, both plant and microbial, highlighting emerging trends of functional conservation between species and across kingdoms, complemented by the heterogeneity of EV subpopulations at the organism level that places EVs as powerful regulatory mechanisms in plant biotic interactions.