Phytocytokines: Key regulators of plant immunity and emerging tools for sustainable agriculture

In plant immunity and stress adaptation, phytocytokines, which are endogenous peptide signals, play a central role in regulating immunological responses. These molecules, functionally similar to animal cytokines, belong to several families, including systemins, phytoelicitor peptides (Peps), and rapid alkalinization factors (RALFs). They act through membrane-bound receptor kinases to coordinate complex signaling cascades. Phytocytokines are essential for both local and systemic immunity. They trigger calcium influx, activate defense-related gene expression, and initiate mitogen-activated protein kinase (MAPK) cascades in response to stress or pathogen attack. This study outlines the molecular functions of major phytocytokines, their hormonal crosstalk with the classical phytohormones salicylic acid (SA), jasmonic acid (JA), and ethylene (ET), which are discussed in relation to phytocytokine signaling and their integration into broader plant immune networks. We also highlight their roles in abiotic stress responses, including salinity and drought, supported by recent physiological and molecular data. Biotechnology strategies such as foliar peptide application, transgenic overexpression, and CRISPR/Cas9-mediated genome editing have been explored as tools to increase crop resilience. Case studies have demonstrated that modifying phytocytokine pathways can increase disease resistance, improve resource efficiency, and promote sustainable farming practices. Despite promising advances, challenges remain in terms of scalability, delivery methods, and signaling complexity. Finally, we discuss the future potential of integrating phytocytokines with omics technologies and gene editing to develop high-yielding, climate-resilient crops.