The known and unknown of wuyiencin: a potent natural product active against phytopathogenic fungi

Wuyiencin is a broad-spectrum agricultural antibiotic used to control fungal diseases in vegetables and crops. This nucleoside-type natural product has been granted an organic certification in China and is produced industrially. Wuyiencin has shown efficacy against several fungal pathogens, notably Botrytis cinerea and Sclerotinia sclerotiorum via inhibition of protein synthesis essentially. Plant infections by other pathogenic fungi, such as Sphaerotheca fuliginea and Didymella segeticola, can be prevented or treated with wuyiencin alone or in combination with other fungicides. In D. segeticola, wuyiencin functions as an inhibitor of threonine dehydratase implicated in pyruvate production and thus blocks ATP production needed for mycelium growth. It is an eco-friendly biopesticide efficient against fungi, with no major toxicity to the soil bacterial community. But surprisingly, wuyiencin is essentially unknown from a chemical viewpoint. An atypical chemical structure, with a tetra-peroxy side chain N-attached to a cytidine unit, has been reported in two patents only. No structural and chemical data are available on wuyiencin. Consequently, the exact wuyiencin structure is subject to controverse, despite its well-established use and the development of new wuyiencin-containing formulations. The present review underlines the agricultural interest of this product based on its mechanism of action and bioactivities. In parallel, the analysis advocates for the implementation of chemical studies on wuyiencin and drug design approaches.