Calcineurin B‐like interacting protein kinase 31 confers resistance to sheath blight via modulation of ROS homeostasis in rice

Sheath blight (ShB) severely threatens rice cultivation and production; however, the molecular mechanism of rice defence against ShB remains unclear. Screening of transposon Ds insertion mutants identified that Calcineurin B‐like protein‐interacting protein kinase 31 (CIPK31) mutants were more susceptible to ShB, while CIPK31 overexpressors (OX) were less susceptible. Sequence analysis indicated two haplotypes of CIPK31: Hap_1, with significantly higher CIPK31 expression, was less sensitive to ShB than the Hap_2 lines. Further analyses showed that the NAF domain of CIPK31 interacted with the EF‐hand motif of respiratory burst oxidase homologue (RBOHA) to inhibit RBOHA‐induced H(2)O(2) production, and RBOHA RNAi plants were more susceptible to ShB. These data suggested that the CIPK31‐mediated increase in resistance is not associated with RBOHA. Interestingly, the study also found that CIPK31 interacted with catalase C (CatC); cipk31 mutants accumulated less H(2)O(2) while CIPK31 OX accumulated more H(2)O(2) compared to the wild‐type control. Further analysis showed the interaction of the catalase domain of CatC with the NAF domain of CIPK31 by which CIPK31 inhibits CatC activity to accumulate more H(2)O(2).