The RLCK subfamily VII-4 controls pattern-triggered immunity and basal resistance to bacterial and fungal pathogens in rice.

Abstract

Receptor-like cytoplasmic kinases (RLCKs) mediate the intracellular signaling downstream of pattern-recognition receptors (PRRs). Several RLCKs from subfamily VII of rice (Oryza sativa) have important roles in plant immunity, but the role of RLCKVII-4 in pattern-triggered immune (PTI) signaling and resistance to pathogens has not yet been investigated. Here, we generated by multiplex CRISPR/Cas9-mediated genome editing rice sextuple mutant lines where the entire RLCKVII-4 subfamily is inactivated and, analyzed the resulting lines for their response to chitin and flg22 and for their immunity to Xanthomonas oryzae pv. oryzae (Xoo)and Magnaporthe oryzae. Analysis of the rlckvii-4 mutants revealed that they have an impaired ROS burst and reduced defense gene expression in response to flg22 and chitin. This indicates that the members of the rice RLCKVII-4 subfamily are required for immune signaling downstream of multiple PRRs. Furthermore, we found that the rice RLCKVII-4 subfamily is important for chitin-induced callose deposition and MAPK activation and that it is crucial for basal resistance against Xoo and M. oryzae pathogens. This establishes that the RLCKVII-4 subfamily has critical functions in the regulation of multiple PTI pathways in rice and opens the way for deciphering the precise role of its members in the control of rice PTI.