Harnessing Plant Antimicrobial Peptides for Crop Protection: From Molecular Defence Mechanisms to Peptide Engineering and Field Applications

Abstract

Plant pathogens destroy a substantial share of global crop production every year, and reliance on conventional agrochemicals is increasingly constrained by resistance evolution, residue regulation and environmental concern. Antimicrobial peptides synthesised by plants as part of their innate immune repertoire offer an alternative route to durable disease control. These small, predominantly cationic and cysteine-rich molecules fall into several structurally distinct families, including defensins, thionins, lipid transfer proteins, snakins, cyclotides and hevein-like peptides, each combining membrane-permeabilising activity with, in many cases, additional intracellular or signalling functions. This review synthesises current understanding of the molecular architecture and mechanisms of action of plant antimicrobial peptides, their integration with pattern-triggered and effector-triggered immune signalling, and the principal strategies used to engineer them for improved potency, stability and selectivity, including rational design, recombinant and transient expression platforms, genome editing and computational discovery pipelines. Approaches for translating these molecules into field-deployable products are examined, spanning transgenic and cisgenic expression, viral-vector-mediated transient expression, nanocarrier-assisted foliar delivery and postharvest application, together with documented cases of disease resistance achieved in model and crop species. Persistent obstacles, including proteolytic instability, high production cost, regulatory uncertainty for genetically modified and gene-edited crops, and limited field-scale validation, are discussed alongside emerging solutions. The review concludes that plant antimicrobial peptides represent a scientifically mature but commercially underexploited resource, and that further progress depends on closer integration of structural biology, synthetic biology and agronomic trial design.