A Colletotrichum gloeosporioides effector Vne1 targets the transcription factor MdAHL17 to subvert MdCNL1 ‐mediated plant immunity in apple

Plants employ nucleotide-binding site-leucine-rich repeat (NBS-LRR) proteins to monitor pathogen-secreted proteins and initiate innate immune responses. This naturally raises the question of how pathogens subvert the NBS-LRR protein-mediated resistance. Here, we characterize a nucleus-localized effector, Vne1, secreted by Colletotrichum gloeosporioides, the causal agent of Glomerella leaf spot of apple (Malus × domestica). We reveal that Vne1 interacts directly with the 'PRGRP' residues of MdAHL17, an apple AHL protein. Our findings indicate that MdAHL17 acts as a transcription factor (TF) governing the expression of MdCNL1. We further show that MdCNL1 encodes a coiled-coil-NBS-LRR protein that enhances apple resistance to C. gloeosporioides. Furthermore, we demonstrate that MdAHL17 binds directly to the promoter region of MdCNL1 through an AT-rich element characterized by a 'TATATATATT' motif. Our study highlights that Vne1 interferes with the DNA-binding affinity of MdAHL17, thereby perturbing MdCNL1-mediated immunity. This elucidates a sophisticated mechanism through which fungal effectors strategically target the TF to subvert the resistance conferred by NBS-LRR proteins during pathogen invasion.