Antimicrobial peptides: emerging next-generation strategy for sustainable plant disease management

Plant diseases reduce agricultural productivity worldwide, and this decline is further accelerated by climate variability, monoculture cultivation systems, and the excessive use of synthetic agrochemicals. Overuse of chemical (synthetic) pesticides in agriculture results in ecological stress, including loss of beneficial microbes. As a solution, antimicrobial peptides (AMPs) are viable natural alternative to antibiotics and pesticides, due to their potent, broad-spectrum, and targeted properties, as well as their low susceptibility to the development of resistance. As small cationic amphipathic molecules found in plants, animals, and microorganisms, these AMPs are known to modulate membrane permeabilisation, disrupt intracellular systems, and stimulate the immune response. The AMP defence system depends on the highly interconnected gene network that supports efficient signal transmission and tightly coordinated gene clusters that support systematic responses to pathogen attack. These molecules can be considered as attractive biocidal agents due to their ability to target microbial membranes and cause rapid cell death, thereby having potential as broad-spectrum biocontrol agents against bacteria, fungi, and viruses. AMPs are also effective against multidrug-resistant pathogens. In plants, AMP families such as defensins, thionins, cyclotides, LTPs (lipid transfer proteins), snakins, and hevein-like peptides act as constitutive "natural antibiotics" which are involved in activating defensive signalling cascades upon pathogen infection. Microbial AMPs, such as bacteriocins, suppress pathogenic and spoilage bacteria by forming pores and inhibiting cell wall synthesis. At the same time, lipopeptides promote beneficial biofilms and plant defence pathways without direct toxicity. Progress in molecular biology, computational modelling, and synthetic biology has revealed the discovery, engineering, and optimisation of AMPs for agriculture. This review summarises the mechanisms of antibiotic mimicry by AMPs and discusses their structural and functional diversity, as well as their potential applications in sustainable plant disease management. The present study also evaluated AMPs as an alternative to chemical pesticides and antimicrobial agents, offering an environmentally compatible, durable, and efficient approach to preventing plant diseases.