<i>OsWRKY22</i>, a monocot <i>WRKY</i> gene, plays a role in the resistance response to blast

<jats:title>SUMMARY</jats:title><jats:p>With the aim of identifying novel regulators of host and nonhost resistance to fungi in rice, we carried out a systematic mutant screen of mutagenized lines. Two mutant <jats:italic>wrky22</jats:italic> knockout lines revealed clear‐cut enhanced susceptibility to both virulent and avirulent <jats:italic>Magnaporthe oryzae</jats:italic> strains and altered cellular responses to nonhost <jats:italic>Magnaporthe grisea</jats:italic> and <jats:italic>Blumeria graminis</jats:italic> fungi. In addition, the analysis of the pathogen responses of 24 overexpressor <jats:italic>OsWRKY22</jats:italic> lines revealed enhanced resistance phenotypes on infection with virulent <jats:italic>M. oryzae</jats:italic> strain, confirming that <jats:italic>OsWRKY22</jats:italic> is involved in rice resistance to blast. Bioinformatic analyses determined that the <jats:italic>OsWRKY22</jats:italic> gene belongs to a well‐defined cluster of monocot‐specific <jats:italic>WRKY</jats:italic>s. The co‐regulatory analysis revealed no significant co‐regulation of <jats:italic>OsWRKY22</jats:italic> with a representative panel of <jats:italic>OsWRKY</jats:italic>s, supporting its unique role in a series of transcriptional responses. In contrast, inquiring a subset of biotic stress‐related Affymetrix data, a large number of resistance and defence‐related genes were found to be putatively co‐expressed with <jats:italic>OsWRKY22</jats:italic>. Taken together, all gathered experimental evidence places the monocot‐specific <jats:italic>OsWRKY22</jats:italic> gene at the convergence point of signal transduction circuits in response to both host and nonhost fungi encountering rice plants.</jats:p>