Unlocking plant defense: Exploring the nexus of biochar and Ca2+ signaling

• Biochar affects soil Ca 2+ dynamics & plant immunity. • Biochar influences priming of defense genes. • Ca 2+ signaling is triggered by biotic and abiotic stress. • Improving environment can improve Ca 2+ fluxes. The interaction between biochar application and calcium ions (Ca 2+ ) in plants, in terms of activating plant defense mechanism would be useful to improve plant resilience and sustainable agriculture. This review aims to highlight the possible connection between biochar-induced changes in soil physicochemical properties, microbial interactions, and Ca 2+ dynamics, ultimately leading to promote the plant defense mechanisms. We are also interested to discuss the role of Ca 2+ signaling in coordinating plant responses to various biotic and abiotic stresses such as pathogen and insects attacks, cold or heat stress and drought stress as well as how Ca 2+ fluxes, calcium-binding proteins, and ion channels are influenced by biochar application in the soil environment. Furthermore, we examine the impact of biochar on plant Ca 2+ signaling pathways and how it can prime defense genes and strengthen call wall barriers to improve plant immunity. Despite significant progress, there is a need for interdisciplinary collaboration to fully sort out the mechanism of Ca 2+ signaling in plants and induction of Ca 2+ ions by biochar induction in soil environment. Advanced imaging techniques, proteomics and omics approaches could be helpful to unlock the complex interaction between biochar application and Ca 2+ signaling. Overall, this review contributes substantially to the literature by describing the relationship between biochar and Ca 2+ signaling and providing insights into novel approaches for enhancing plant defense mechanisms and development of sustainable agricultural solutions.