The Plants are often threatened by several biotic as well as abiotic stresses and have developed sophisticated systems to detect and respond to these challenges. Their responses involve complex molecular signalling, mainly regulated by phytohormones small molecules playing a pivotal role in defense and further development. The defense system of plants involves PAMP-triggered immunity (PTI) and effector-triggered immunity (ETI) cascade, following a zigzag model. Hormones such as auxins, gibberellins (GAs), cytokinin’s (CKs), salicylic acid (SA), abscisic acid (ABA), jasmonic acid (JA), ethylene (ET), and brassinosteroids (BRs) coordinate responses against the stress through the interactions, known as hormonal crosstalk. Pathogens often alter hormone signalling pathways to weaken plant immunity and facilitate infection. Gaining deeper insights into hormonal regulation is crucial for enhancing disease resistance in plants. Hormonal treatments can reprogram host metabolism and gene expression, thereby influencing resistance to microbial pathogens. The effects of these hormones vary with the nature of plant–pathogen interactions, with different hormones exerting either positive or negative effects on defenses against biotrophic, hemibiotrophic or necrotrophic pathogens. Phytohormones work together to regulate gene networks, allowing plants to adapt to environmental changes while maintaining growth and development.
Phytohormones, Plant immunity, Signalling pathways, Gibberelins, Salicylic acid
Bari, R., & Jones, J. D. (2009). Role of plant hormones in plant defence responses. Plant Molecular Biology, 69, 473–488.
Berens, M. L., Berry, H. M., Mine, A., Argueso, C. T., & Tsuda, K. (2017). Evolution of hormone signalling networks in plant defense. Annual Review of Phytopathology, 55(1), 401–425.
Kazan, K., & Lyons, R. (2014). Intervention of phytohormone pathways by pathogen effectors. The Plant Cell, 26(6), 2285–2309.
Liu, Y., Sun, T., Sun, Y., Zhang, Y., Radojičić, A., Ding, Y., Tian, H., Huang, X., Lan, J., & Chen, S. (2020). Diverse roles of the salicylic acid receptors NPR1 and NPR3/NPR4 in plant immunity. Plant Cell, 32, 4002–4016.
Navarro, L., Bari, R., Achard, P., Lisón, P., Nemri, A., Harberd, N. P., & Jones, J. D. (2008). DELLAs control plant immune responses by modulating the balance of jasmonic acid and salicylic acid signalling. Current Biology, 18(9), 650–655.
Pieterse, C. M., Van der Does, D., Zamioudis, C., Leon-Reyes, A., & Van Wees, S. C. (2012). Hormonal modulation of plant immunity. Annual Review of Cell and Developmental Biology, 28(1), 489–521.
Tian, H., Xu, L., Li, X., & Zhang, Y. (2025). Salicylic acid: The roles in plant immunity and crosstalk with other hormones. Journal of Integrative Plant Biology, 67(3), 773–785.
Vinod, K., & Sabah, A. (2018). Plant defense against pathogens: The role of salicylic acid. Research Journal of Biotechnology, 13(12), 97–103.
Wu, D., Tian, H., Xu, F., Yang, J., Feng, W., Bell, S., Gozdzik, J., Gao, F., Jetter, R., & Zhang, Y. (2024). The prodomain of Arabidopsis metacaspase 2 positively regulates immune signalling mediated by pattern‐recognition receptors. New Phytologist, 241(1), 430–443.
