FIGURE 6.

Extracellular vesicle roles in interactions of plants with fungi and oomycetes. Plants and their eukaryotic pathogens exchange EVs during infection. Plant EVs carrying Tetraspanin8 (Tet8) but lacking syntaxin PEN1 (TET8+ PEN1– EVs) carry small RNAs (sRNAs) and other defense compounds including small molecules, enzymes and other proteins. The specific role of plant TET8-negative PEN1-positive (TET– PEN1+) EVs remains unclear. Some of those molecules may enter the pathogen cytoplasm or the nucleus where sRNAs may bind to pathogen RNA-induced silencing complexes (RISC); some enzymes such as callose synthase may be targeted to papillae to strengthen cell wall defenses against pathogen invasion. Pathogen EVs may carry sRNAs as well as other virulence compounds, possibly including some effectors. sRNAs may target plant RISC complexes. MVBs, multivesicular bodies; PRR, pattern recognition receptor; BAK1, BRASSINOSTEROID INSENSITIVE 1-associated receptor kinase 1; SOBIR1, suppressor of BRASSINOSTEROID INSENSITIVE 1 (BRI1)-associated kinase (BAK1)-interacting receptor kinase 1.