The Ca2+ Channel CYCLIC NUCLEOTIDE GATED CHANNEL13 (CNGC13) regulates systemic wound signalling and immunity against Spodoptera herbivory

Abstract

Insect herbivory elicits rapid and complex signalling responses in plants, including membrane depolarization, cytosolic Ca2+ elevation and activation of jasmonate-mediated defense pathways in local and systemic leaves. These early events are orchestrated by calcium-permeable channels and regulatory components that generate stimulus-specific cytosolic Ca2+ signatures. However, the molecular mechanisms that generate long-distance Ca2+ propagation and systemic immune activation on herbivory remain poorly defined. Here, we identify CYCLIC NUCLEOTIDE GATED CHANNEL13 (CNGC13) as a novel plasma membrane-localized, phloem-expressed Ca2+ channel that is essential for systemic wound signalling and defense against lepidopteran pest, Spodoptera litura in Arabidopsis thaliana. CNGC13 is rapidly induced by wounding and herbivory, mediates cytosolic Ca2+ influx, and is required for efficient propagation of Ca2+ signals from wounded to distal leaves. Loss of CNGC13 compromises the thioglucosidase-dependent breakdown of aliphatic glucosinolates into aglucones/isothiocyanates within the vascular tissue, which are essential for wounding-induced systemic Ca2+ wave propagation. Consequently, cngc13 mutants display impaired systemic jasmonate accumulation in distal leaves, reduced glucosinolate levels and enhanced herbivore susceptibility. CNGC13 is also required for AtPep-induced Ca2+ elevation and Reactive Oxygen Species (ROS) signalling and interacts with the receptor kinase, PEPR2, implicating it in DAMP-mediated immune responses. Although CNGC13 and CNGC19 function cooperatively in herbivore defense, they do not physically interact, suggesting independent but converging roles. Our study identifies CNGC13 as a vasculature-localized Ca2+-permeable channel that functions downstream of PEPR2 receptor, to sustain systemic signalling, operating in a distinct yet converging pathway alongside known glutamate receptor-like channels during long-distance wound responses. SignificancePlants must detect and respond to insect herbivory rapidly by activating systemic immunity to trigger defense responses. Calcium (Ca2+) signalling plays a central role in this defense network, yet the identities and specific functions of Ca2+ channels involved in long-distance herbivory signalling remain poorly understood. Here, we identify the plasma membrane-localized channel CYCLIC NUCLEOTIDE GATED CHANNEL13 (CNGC13) as a key integrator of mechanical damage perception, ricca factor-mediated systemic signalling, and jasmonate-dependent defense against Spodoptera herbivory in Arabidopsis. CNGC13 facilitates systemic Ca2+ wave propagation, activates jasmonate and glucosinolate biosynthesis, and promotes the perception of damage-associated molecular pattern (DAMP) molecules to confer herbivore resistance. This work uncovers a previously uncharacterized calcium channel that plays a crucial dual role in systemic wound signalling.