Tomato Brown Rugose Fruit Virus Evades Tm‐2 2 ‐Mediated Resistance by Avoiding the Induction of Tm‐2 2 Self‐Association

ABSTRACT Tomato brown rugose fruit virus (ToBRFV) overcomes Tm‐2 2 ‐mediated resistance, posing a serious threat to global tomato production. We previously identified that key residues in the movement protein (MP)‐H67, N125, K129, A134, I147 and I168 are essential for ToBRFV evasion of Tm‐2 2 resistance. However, the underlying mechanisms remain unclear. In Tm‐2 2 ‐transgenic Nicotiana benthamiana plants at later infection stages, MP mutations H67C, N125A, K129Q and A134N abolished ToBRFV‐GFP cell‐to‐cell and systemic movement, whereas I168N abolished ToBRFV‐GFP systemic but not cell‐to‐cell movement, and I147M partially impaired both. Correspondingly, the MP H67C , MP N125A , MP K129Q and MP A134N mutants elicited strong Tm‐2 2 ‐mediated hypersensitive response (HR), MP I168N elicited mild HR and MP I147M elicited none. Confocal microscopy revealed I147M reduced MP localisation at plasmodesmata in Tm‐2 2 ‐transgenic N. benthamiana leaves. The interaction with Tm‐2 2 was weak for wild‐type MP and I147M (slightly enhanced), but moderately or strongly enhanced for I168N and the other four mutants. Wild‐type MP and MP I147M failed to induce Tm‐2 2 self‐association, MP I168N only weakly induced it, whereas the other four markedly induced it. Collectively, these findings demonstrate that ToBRFV evades Tm‐2 2 ‐mediated resistance by attenuating MP–Tm‐2 2 interaction strength, thereby avoiding Tm‐2 2 self‐association and downstream immune activation.