Applications of aptamer-based electrochemical biosensors for the specific recognition of plant pathogenic fungi and mycotoxins

Plant pathogenic fungi represent a formidable threat to global food security, causing substantial pre- and post-harvest crop losses annually. The effective management of fungal diseases is contingent upon early, accurate, and on-site detection, a capability that traditional diagnostic methods fail to provide. In response to this diagnostic gap, aptamer-based electrochemical biosensors have emerged as a powerful and promising technological platform. Aptamers, synthetic single-stranded oligonucleotides, offer significant advantages over traditional antibodies, including superior stability, cost-effective synthesis, and facile modification, making them ideal recognition elements for robust, field-deployable sensors. This review provides a comprehensive and critical analysis of the state-of-the-art in this burgeoning field. We first establish the agricultural imperative for advanced fungal diagnostics by evaluating the limitations of conventional methods. We then delve into the core of the technology, critically examining the strategies for aptamer selection against complex fungal targets, from whole spores to specific molecular biomarkers, and dissecting the inherent trade-offs between physiological relevance and mechanistic certainty. The principles of electrochemical transduction are explored, with a detailed analysis of sensor architectures, including labeled versus label-free and signal-on versus signal-off designs, highlighting the causal link between the target's nature and the optimal sensor configuration. Furthermore, we provide an exhaustive overview of signal amplification strategies, focusing on the multifunctional roles of nanomaterials and nucleic acid amplification techniques in achieving the sensitivity required for early-stage infection detection. Through specific case studies on economically significant pathogens such as Fusarium spp. , Magnaporthe oryzae , Botrytis cinerea , and Puccinia striiformis , we illustrate the practical application of these principles. Finally, we confront the overarching challenges that currently impede the transition from laboratory prototypes to commercially viable field instruments, and we outline the future trajectory of the field, emphasizing multiplexed detection and integration with smart agricultural technologies.