The MeCNL3-MeARF6 module plays an important role in cassava bacterial blight resistance

Abstract

Cassava bacterial blight (CBB) poses a substantial threat to the progression and sustainability of the cassava industry. While the NLR gene family is known to play a crucial role in plant disease resistance by encoding intracellular immune receptors, the specific molecular mechanisms underlying NLR-mediated resistance in cassava remain poorly understood and require comprehensive characterization. Our research identified MeCNL3, a CC-NBS-LRR resistance gene, demonstrating significant upregulation in response to Xanthomonas axonopodis pv. manihotis (Xam) infection. Functional characterization revealed that MeCNL3 overexpression confers enhanced resistance to Xam in cassava. Meanwhile, we demonstrated that MeCNL3 physically interacts with the transcription factor MeARF6, forming a regulatory module that controls Xam resistance. Notably, experimental evidence confirms that MeARF6 regulates MeRbohH transcription, orchestrating reactive oxygen species (ROS)-mediated defense responses against CBB. Furthermore, the type III effector protein XopR hijacks MeCNL3 to suppress the MeCNL3-MeARF6 signaling module, thereby weakening CBB resistance. Taken together, this work delineates the molecular mechanism of MeCNL3-driven CBB immunity and advances the understanding of NLR regulatory networks in cassava defense responses.