SynComs as novel delivery systems for dsRNA-based crop protection: design principles, challenges, and future prospects1

RNA interference (RNAi) offers a precise and environmentally sustainable approach to crop protection, yet its widespread field application is constrained by the rapid degradation of double-stranded RNA (dsRNA), inefficient pathogen uptake, and variable performance of both host-induced and spray-induced gene silencing strategies. In this review, we propose synthetic microbial communities (SynComs) as microbially integrated delivery systems designed to overcome these limitations. We introduce a functional framework in which SynCom members are rationally assigned specialized roles dsRNA producers, stabilizers, carriers, and helpers to enable continuous in situ RNA production, protection against nucleases and environmental stressors, and targeted delivery to pathogens across the rhizosphere, phyllosphere, and endosphere. We discuss niche-specific design principles, microbiome engineering strategies, and biosafety considerations essential for translating SynCom-mediated RNAi into robust field applications. Importantly, we address the emerging challenges, posed by agro-environmental pollutants such as microplastics, heavy metals, and pesticide residues and propose how engineered pollutant-tolerant SynComs can maintain RNAi efficacy in contaminated agroecosystems. Finally, we present a phased translational roadmap that progresses from combined SynCom-dsRNA sprays toward programmable self-regulating SynComs capable of adaptive dsRNA delivery. By bridging RNAi biotechnology, microbial ecology, and synthetic biology, this integrated SynCom-based platform offers a scalable, durable, and ecologically resilient strategy to reduce reliance on synthetic chemical inputs and enhance crop protection under real-world field conditions.