A Calcium-Dependent Protein Kinase Regulates the Defense Response in .

Citrus Huanglongbing (HLB), which is caused by ' Liberibacter asiaticus' (CLas), is one of the most destructive citrus diseases worldwide, and defense-related gene resources remain largely unexplored. Calcium signaling plays an important role in diverse biological processes. In plants, a few calcium-dependent protein kinases (CDPKs/CPKs) have been shown to contribute to defense against pathogenic microbes. The genome of encodes dozens of CPKs. In this study, the role of calcium-dependent protein kinases (CsCPKs) in defense was investigated. Silencing of compromised the induction of defense-related genes in . Expression of a constitutively active form of CsCPK6 (CsCPK6) triggered the activation of defense-related genes in . Complementation of CsCPK6 rescued the defense-related gene induction in an mutant, indicating that CsCPK6 carries CPK activity and is capable of functioning as a CPK in . Moreover, an effector derived from CLas inhibits defense induced by the expression of and autophosphorylation of CsCPK6, which suggests the involvement of CsCPK6 and calcium signaling in defense. These results support a positive role for CsCPK6 in defense against CLas, and the autoinhibitory regulation of CsCPK6 provides a potential genome-editing target for improving defense. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.