Antimicrobial Photodynamic Therapy in Plants

Fungal and bacterial plant diseases severely threaten global food security. Excessive use of chemical fungicides has caused widespread pathogen resistance and severe risks to ecosystems and human health. Antimicrobial photodynamic therapy (aPDT) serves as a sustainable alternative for crop protection. Upon the combination of photosensitizers, light, and oxygen, aPDT produces reactive oxygen species (ROS) that disrupt pathogen biomolecules and evade common resistance mechanisms. Their applications span the entire crop life cycle, demonstrating remarkable efficacy in seed desinfection, foliar disease control, and postharvest preservation. Importantly, aPDT-derived ROS activate plant systemic acquired resistance (SAR) to defend against subsequent infections. In this review, we systematically categorize recent agricultural advancements based on the structural classes of photosensitizers, including porphyrins, phthalocyanines, coumarins, phenothiazines, BODIPYs, and triphenylamines. Moreover, it also highlights current limitations and outlines future research prospects to facilitate the commercialization of photodynamic agrochemicals.