P-042 - Functional Characterization of 16 GKL-type Plant U-box (PUB) Genes in Rice Blast Resistance

Rice blast, caused by the fungal pathogen Magnaporthe oryzae, is a globally prevalent disease, causing substantial yield losses and leading to total crop loss during severe outbreaks. Plant U-box E3 ubiquitin ligases (PUBs) have been identified as critical regulators of plant development, immune responses, and adaptation to abiotic stresses. In this study, we analyzed the function of 16 GKL-type rice PUB genes (OsPUB31-46) in rice blast resistance. Transcriptome analysis of Magnaporthe oryzae-treated leaves revealed that 9 out of 16 OsPUBs were upregulated at 3–4 days post-inoculation, with OsPUB41 exhibiting the highest induction (341.3-fold). Using an arrayed CRISPR/Cas9 library construction strategy, we generated 132 positive transgenic plants covering 14 OsPUB genes, while the 2 uncovered OsPUB genes are likely essential for rice development. Screening of 14 ospub mutants through M. oryzae inoculation revealed that ospub42 and ospub45 were more susceptible to rice blast infection, and ospub41 was more resistant. Furthermore, a yeast two-hybrid screen revealed that OsPUB41 interacts with at least 66 proteins, including receptor-like cytoplasmic kinases (RLCKs), mitogen-activated protein kinases (MAPKs) and calcium-dependent protein kinases (CDPKs). These results suggest that OsPUB41 is a central regulator of rice immunity.