Distinct ankyrin repeat subdomains control VAPYRIN locations and intracellular accommodation functions during arbuscular mycorrhizal symbiosis

Abstract

AbstractOver 70% of vascular flowering plants engage in endosymbiotic associations with arbuscular mycorrhizal (AM) fungi. VAPYRIN (VPY) is a plant protein that is required for intracellular accommodation of AM fungi but how it functions is still unclear. VPY has a large ankyrin repeat domain with potential for interactions with multiple proteins. Here we show that overexpression of the ankyrin repeat domain results in a vpy-like phenotype, consistent with the sequestration of interacting proteins. We identify distinct ankyrin repeats that are essential for intracellular accommodation of arbuscules and reveal that VPY functions in both the cytoplasm and nucleus. VPY interacts with two kinases, including DOES NOT MAKE INFECTIONS3 (DMI3), a nuclear-localized symbiosis signaling kinase. Overexpression of VPY in a symbiosis-attenuated genetic background results in a dmi3 -like phenotype suggesting that VPY negatively influences DMI3 function. Overall, the data indicate a requirement for VPY in the nucleus and cytoplasm where it may coordinate signaling and cellular accommodation processes.