Plant Elicitor Peptide Mediated Signalling Cascades During Plant–Pathogen Interaction

The constant coevolution between plants and pathogen species causes pathogens to evolve into new strains to evade immune system of plants. Concurrently, plants continue to generate a vast array of different elicitor peptides, small signalling molecules with pivotal roles in orchestrating defence strategies against various biotic stresses, such as pathogen attacks. This chapter delves into elucidating the multifaceted functions and molecular mechanisms involving the regulatory signalling cascades of several peptides, including plant defensins (PDFs), systemin, thionin, hevein-like peptides, knottin-type peptides, α-hairpin family peptides, lipid transfer protein, snakins, Pep2 and 3 (plant elicitor peptides), cyclotides, puroindolines, AtPeps, rapid alkalinization factor 23 (RALF23), PIP1 and 2 (PAMP-induced secreted peptides), serine-rich endogenous peptide 12 (SCOOP12), CLV1 (CLAVATA 1), HYPSYS (hydroxyproline-rich glycopeptide systemins) peptides, PSK (phytosulfokine), and PSY1 (plant peptide containing sulphated tyrosine 1). These peptides ultimately activate the expression of defence-related genes, the production of antimicrobial compounds, and the induction of systemic acquired resistance (SAR) to strengthen plant immunity against pathogen attack (biotic stress). Furthermore, this chapter discusses some of their potential applications in genetic engineering, emphasising the use of these peptides as biocontrol agents as alternatives to harmful chemical pesticides and insecticides. This approach aims to improve crop protection, tolerance, resilience, and resistance from subsequent pathogen infections, leading to sustainable agricultural practises, including improvements in crop quality and yield. Such strategies can be economically advantageous for farmers while simultaneously meeting all criteria for global food security.