Next-Generation Cyanobacterial Biocontrol Agents for Crop Fungal Diseases: Molecular Mechanisms, Omics Insights, Applications, and Biosafety Considerations.

Fungal diseases are major constraint to global crop production, causing substantial losses and increasing reliance on chemical fungicides. Cyanobacteria offers a sustainable alternative for disease managment due to their ability to produce antifungal metabolites, including volatile organic compounds (VOCs), exopolysaccharides (EPS), and lytic enzymes. These bioactive molecules suppress phytopathogenic fungi by disrupting cell membranes, inhibiting virulence factors, inducing oxidative stress, and degrading cell wall components. Cyanobacteria also enhance plant defence responses by activating salicylic acid (SA), jasmonic acid (JA), ethylene, and nitric oxide (NO) signaling pathways, leading to upregulation of defense-related genes, including PR proteins, PAL, and WRKY transcription factors. Recent multi-omics approaches have provided valuable insights into biosynthetic gene clusters, regulatory networks, and metabolic pathways underlying cyanobacterial antifungal activity. Although laboratory evidence is encouraging, field application remains challenging by environmental variability and formulation limitations. Emerging advances in genome mining and synthetic biology may enhance the effectiveness of cyanobacterial biocontrol agents. This review highlights current progress in cyanobacteria-mediated management of fungal diseases, discusses biosafety considerations, and outlines future research directions for developing eco-friendly and sustainable crop protection solutions.