Find in Library

Rice bacterial blight caused by <i>Xanthomonas oryzae</i> pv. <i>oryzae</i> (<i>Xoo</i>) seriously affects rice yield production. The discovery and application of broad-spectrum resistance genes are of great advance for disease resistance breeding. Previously, we identified that multiple <i>receptor-like kinase (RLK)</i> family gene deletions induced by the <i>Ac/Ds</i> system resulted in a lesion mimic symptom. In this study, the mutant #29 showed that this lesion mimic symptom was isolated. Further analysis identified that four <i>RLK</i> genes <i>(</i><i>RLK19-22)</i> were deleted in the #29 mutant. The #29 mutant exhibited broad-spectrum resistance to <i>Xoo</i> and subsequent analyses identified that pathogenesis-related genes <i>PR1a, PBZ1</i>, and cellular H₂O₂ levels were significantly induced in the mutant compared to wild-type plants. A genetic analysis revealed that reconstruction of <i>RLK20</i>, <i>RLK21,</i> or <i>RLK22</i> rescued the lesion mimic symptom of the #29 mutant, indicating that these three <i>RLKs</i> are responsible for broad-spectrum resistance in rice. Further yeast two hybrid and bimolecular fluorescence complementation assays demonstrated that RLK20 interacts with RBOHB, which is a ROS producer in plants. Compared to wild-type plants, the #29 mutant was more, while #29/<i>RLK20</i><i>ox</i> was less, susceptible to MV (methyl-viologen), an ROS inducer. Co-expression of <i>RLK20</i> and <i>RBOHB</i> reduced RBOHB-promoted H₂O₂ accumulation in the cells. Taken together, our research indicated that the RLKs may inhibit RBOHB activity to negatively regulate rice resistance to <i>Xoo</i>. These results provide the theoretical basis and valuable information about the target genes necessary for the successful breeding of rice cultivars resistant to bacterial blight.