Antifungal Biocontrol in Sustainable Crop Protection: Microbial Lipopeptides, Polyketides, and Plant-Derived Agents

Fungal phytopathogens cause significant global crop losses and remain a constant obstacle to sustainable food production. Biological control has become a vital alternative to synthetic fungicides, supported by the wide variety of antifungal molecules produced by bacteria, fungi, yeasts, and plants. This review consolidates current knowledge on the main classes of microbial secondary metabolites-particularly cyclic lipopeptides and polyketides from Bacillus, Pseudomonas, Streptomyces, Trichoderma, and related generа. It emphasizes their structural diversity, biosynthetic pathways, regulatory networks, and antifungal mechanisms. These molecules, including iturins, fengycins, surfactins, syringomycins, candicidins, amphotericin analogs, peptaibols, and epipolythiodioxopiperazines, target fungal membranes, mitochondria, cell walls, and signaling systems, offering broad activity against damaging pathogens such as Fusarium, Botrytis, Magnaporthe, Colletotrichum, Phytophthora, and Rhizoctonia. The plant-derived antifungal metabolites include essential volatile compounds that complement microbial agents and are increasingly important in eco-friendly crop protection. Recent progress in genomics, metabolic engineering, and synthetic biology has accelerated strain improvement and the discovery of new bioactive compounds. At the same time, global market analyses indicate rapid growth in microbial biofungicides driven by regulatory changes and consumer demand.