Electrical and calcium signaling in plant systemic defense: from local wounds to global responses

Sessile plants, constrained by their immobile nature in dynamic environments, have evolved sophisticated defense mechanisms to ensure survival. When confronted with threats such as insect feeding or mechanical wounding, plants not only activate localized defense responses at the injury site but also quickly transmit danger signals from the wound to the distal undamaged tissues for the activation of systemic defense signaling, which enables the plant to prepare for the upcoming threats effectively. Emerging evidence highlights the pivotal role of vascular-mediated long-distance transmission of electrical signals and calcium (Ca²⁺) waves in coordinating whole-plant defense programs. Recent advances have significantly expanded our understanding of wound-induced systemic signaling, with key genes and signaling molecules identified as central components in these cascades. In this review, we first provide an overview of these key findings and then discuss the mechanisms driving the long-distance transmission of electrical and Ca²⁺ signals. Furthermore, we explore the roles of wound- and mechanically stimulated electrical and Ca²⁺ signals in other plant species, contributing to a broader understanding of plant defense responses.