Genome-wide PfSWI/SNF characterization identifies PfSWP73B2 as a target of effector Pawb57 in regulating gibberellin-mediated juvenile shoot growth

The SWI/SNF chromatin remodeling complex is pivotal in regulating gene expression, yet its functions in woody perennials, particularly under biotic stress, remain largely unexplored. Here, we performed a genome-wide analysis of SWI/SNF complex subunits in Paulownia fortunei and identified 51 members with diverse physicochemical properties, gene structures, and protein domains. Expression profiling revealed that the SWI/SNF subunit PfSWP73B2 emerged as a key candidate involved in pathogen stress response. Functional characterization demonstrated that overexpression PfSWP73B2 in poplar significantly increased height at the juvenile stage, concomitant with elevated gibberellin levels. Protein–protein interaction assays confirmed that PfSWP73B2 interacts with the DELLA repressor PfRGA1, linking chromatin remodeling to gibberellin signaling in paulownia. Furthermore, we identified that the phytoplasma effector Pawb57 is up-regulated during infection and targets PfSWP73B2 in the nucleus. Together, these findings uncover a molecular mechanism by which a pathogen effector subverts host chromatin remodeling to manipulate hormone signaling and promote disease development, offering new insights into the epigenetic regulation of plant-pathogen interactions.