Li, P.; Kelley, B.; Li, Z.; Procter, B.; Corrion, A.; Xie, X.; Sheick, R.; Lu, Y.-j.; Nomoto, M.; Wei, C.-i.; Tada, Y.; He, S.-Y.; Xiao, S.; Day, B.

Remodeling of the actin cytoskeleton during the activation of plant immunity is a critical process for the transport and stabilization of immune regulatory organelles and molecules. In this process, actin depolymerization factors (ADFs) function as key player through both severing and depolymerizing actin microfilaments. However, recent evidence suggests that ADFs may possess non-canonical immune functions inside the nucleus, in addition to a cytosolic role, a phenomenon not adequately explained by the traditional mechanistic model of ADFs and actin. In this study, we demonstrate that ADFs indeed have a moonlighting function in the nucleus, interacting with transcriptional machinery and regulating the transcriptome during both resting states and immune responses. Specifically, ADF2/3/4 exhibit redundant functions in defense against virulent and avirulent Pseudomonas, but not certain species of Pectobacterium and powdery mildew. Notably, nuclear, rather than cytosolic, ADFs contribute to defense against Pseudomonas and mediate pro-immune transcription. Mechanistically, we demonstrate that nuclear ADFs interact with transcription factors, histone complexes, and other components of the transcriptional machinery. Specifically, ADF2/3/4 can form a complex with WRKY transcription factors (such as WRKY22/29/48), thereby binding to promoters and directly regulating WRKY activity to shape the pro-immune transcriptome. In summary, our study reveals that ADFs moonlight as direct nuclear regulators of transcription factors, mediating a broad range of nuclear-cytoplasmic regulation of plant immunity and other processes.