IJPB Seminar Martin Potocký

The exocyst is an evolutionarily conserved octameric vesicle-tethering complex that mediates the first contact between secretory vesicles and the plasma membrane. In plants, this ancient machinery has been extensively remodeled: several subunits — most dramatically EXO70 — have multiplied into large paralog families whose origins and functions have long remained enigmatic. I will present our work tracing how the plant exocyst reads membrane identity and how its diversification gave rise to specialized secretion pathways. We showed that the plant exocyst is recruited to the plasma membrane primarily through EXO70 subunit, which recognizes a plant-specific anionic phospholipid signature. Phylogenomic reconstruction across streptophytes, combined with cross-species functional complementation, reveals that the three major EXO70 subfamilies originated at the dawn of plant terrestrialization, and that land-plant SEC3 lost its ancestral autonomous membrane-binding capacity, shifting the burden of exocyst targeting onto EXO70 paralogs. This evolutionary rewiring enabled specialized exocyst modules: we have recently identified a plasmodesmata-associated exocyst built around EXO70G1 that regulates callose turnover, thereby controlling symplastic connectivity, development, and antibacterial defense. Together, these findings establish EXO70 diversification as a key innovation that links membrane lipid codes to the evolution of targeted secretion during the conquest of land.

Martin Potocký, "Institute of Experimental Botany" IEB, Czech Academy of Sciences, Czech Republic

Invitation:  Kalina Haas, "Physiology of plant cell wall assembly, remodelling, and expansion" phyWALL team


Seminar in connection with the research developed at theInstitute Jean-Pierre Bourgin for Plant Sciences.