UNCOVERING THE TARGETS OF TOBAMOVIRUS MOVEMENT PROTEIN THAT PROMOTE SUSCEPTIBILITY AND EVADE HOST IMMUNITY

Plant viruses of the tobamovirus genus depend on their movement protein (MP) for cell-to-cell movement to allow systemic infection. A recent outbreak of a new tobamovirus, Tomato brown rugose fruit virus (ToBRFV) threatens the global tomato industry. ToBRFV overcomes all known tobamovirus resistances in tomatoes, including the durable Tm-2(2) immune receptor-mediated resistance. The Tm-2(2) protein recognizes tobamovirus MP to confer resistance. Our recent findings established that Tm-2(2) fails to recognize the ToBRFV MP and the same ToBRFV-MP polymorphisms that determine Tm-2(2) evasion also control cell-to-cell movement.The major goal of this project is to study the MP interaction network during viral pathogenesis. We hypothesize that multiple, yet specific interactions between the viral MP and host proteins determine host resistance and susceptibility. Based on this hypothesis, we propose following specific objectives:Objective 1: Study the trade-off between MP function and Tm-2(2) immune evasion. We will determine elements in MP that both regulate viral movement and promote evasion of host immunityObjective 2: Characterize the function of novel MP-associated proteins. We will characterize novel MP-interacting proteins that we have identified using TurboID-based proximity labeling approach using genetic, cellular and biochemical approaches to understand their role in tobamovirus pathogenesis and evasion of host immunityObjective 3: Study the function of MP-associated proteins in tomatoes. Using CRISPR/Cas9, we will mutate genes encoding MP interactors in tomato and test their function in tobamovirus resistanceAt the completion of the project, we expect to gain fundamental insights on the mechanisms underlying MP function in viral pathogenesis and immunity. These discoveries could lead to the development of novel approaches for tobamovirus resistance in tomatoes and other important solanaceous crops.