HARNESSING THE PLANT MICROBIOME: ENGINEERING SYNTHETIC MICROBIAL CONSORTIA FOR BROAD-SPECTRUM FUNGAL PATHOGEN SUPPRESSION

Fungal pathogens represent one of the most significant threats to global food security, causing devastating yield losses in major crops worldwide. Traditional biological control strategies have relied predominantly on single-strain inoculants such as Trichoderma and Bacillus species. While effective under controlled conditions, these single-agent approaches frequently exhibit inconsistent performance under field conditions due to poor colonization, limited functional redundancy, and susceptibility to environmental fluctuations. The engineering of synthetic microbial communities (SynComs)—carefully designed multi-strain consortia that mimic natural microbiome assemblies—offers a transformative alternative. This review critically examines the shift from single biocontrol agents to rationally designed SynComs for broad-spectrum fungal pathogen suppression. We evaluate the synergistic antifungal mechanisms that emerge from multi-strain interactions, including complementary siderophore production, enhanced volatile organic compound profiles, and the induction of systemic resistance through integrated plant immune signaling. The critical challenges of delivery formulation—encompassing encapsulation technologies and seed coating strategies—are assessed alongside the persistent obstacles of field persistence and interactions with native soil microbiota. Our analysis reveals that well-structured SynComs consistently outperform single strains and random assemblages, with cross-kingdom (bacterial-fungal) consortia demonstrating particularly robust disease suppression. However, significant gaps remain in understanding SynCom dynamics under field conditions, long-term community stability, and the ecological consequences of introducing synthetic consortia into agricultural soils. We identify future directions, including machine learning-guided SynCom design, precision delivery systems, and the integration of SynComs into integrated pest management frameworks.