Pathogen‐Induced Endogenous Small Peptide Phytosulfokine Perceived by the Membrane Receptor OsPSKR2 Enhances Disease Resistance in Rice

Rice blast, caused by the fungus Magnaporthe oryzae, severely impacts rice yield and quality. Plants possess intricate molecular mechanisms to recognize and respond to pathogen infections. In this study, we demonstrated that the infection of M. oryzae induces the expression of prePSK, the precursor of the endogenous small peptide, phytosulfokine, in rice. The exogenous application of active PSKα significantly enhances rice resistance to rice blast. Conversely, the PSK septuple mutant exhibits reduced resistance against M. oryzae, indicating the involvement of PSK in the defense response against rice blast. Through genetic and biochemical evidence, we identified OsPSKR2 as a functional PSK receptor that is essential for PSK-mediated rice blast resistance. Intriguingly, the overexpression of OsPSKR2 promotes the expression of pathogenesis-related (PR) genes and increases reactive oxygen species (ROS) production, thus strengthening rice blast resistance without negatively affecting plant growth or yield. Moreover, we established that the OsPSK-PSKR2 signaling cascade, whose activity depends on OsTPST-mediated PSK tyrosine sulfation, is necessary for immunity against both rice blast and leaf blight. Thus, our study elucidates the role of PSK-PSKR module in broad-spectrum disease resistance in rice.