P-134 - A blast pathogen Zinc Finger fold effector targets Tubby-like F-box proteins

Magnaporthe oryzae is a devastating fungal plant pathogen that delivers effector proteins to manipulate host signalling pathways and impact plant immunity. Effectors frequently group into structural families, maintaining a conserved fold while diversifying sequence to evade recognition and/or gain novel functions. One such family is the Zinc Finger (ZiF) fold family, which includes AVR-Pii. AVR-Pii binds to specific rice Exo70 alleles, triggering immune recognition. However, other ZiF family members do not interact with OsExo70, suggesting neofunctionalization. To investigate the roles of different ZiF effectors, we conducted IP-MS experiments to search for novel interactions. For one effector we identified Tubby-like protein 7 (TLP7) and confirmed the interaction of the effector (Tubby interacting effector 1 (Tie1)) with rice TLP7 by co-IP. TLPs are highly conserved proteins across plants, containing N-terminal F-box and C-terminal Tubby domains. Tubby domains are known to bind phosphatidylinositol-4,5-bisphosphate (PIP2) and act as transcriptional activators. We show that Tie1 directly binds to the Tubby domain of rice TLP7. Intriguingly, overexpression of the Tubby domain fused to GAL4 in N. benthamiana induces strong cell death, which is suppressed by Tie1, indicating a role for the effector in immune modulation. These findings reveal a novel function for a ZiF effector and sheds light on the understudied role of TLPs in plant immunity.