Paladin, a tyrosine phosphatase-like protein, is required for -mediated immunity in rice.

encodes a rice immune receptor that confers robust resistance to most strains of the Gram-negative bacterium pv. ()-mediated immunity is triggered by recognition of a small protein called RaxX-sY (required for activation of -mediated immunity X, tyrosine-sulfated) secreted by To identify components regulating -mediated immunity, we generated and screened a mutant population of fast-neutron-mutagenized rice expressing for those susceptible to . Here, we report the characterization of one of these rice mutants, named (). Whole-genome sequencing revealed that carries a deletion of the () gene encoding a protein with three putative protein tyrosine phosphatase-like domains (PTP-A, -B, and -C). Expression of in the genetic background was sufficient to complement the susceptible phenotype, which requires the catalytic cysteine of the PTP-A active site to restore resistance. PALD co-immunoprecipitated with the full-length XA21 protein, whose levels are positively regulated by the presence of the transgene. Furthermore, we foundd that retains many hallmarks of -mediated immunity, similar to the wild type. These results reveal that PALD, a previously uncharacterized class of phosphatase, functions in rice innate immunity, and suggest that the conserved cysteine in the PTP-A domain of PALD is required for its immune function.