Biodegradable, lignin-based encapsulation enables delivery of Trichoderma reesei with programmed enzymatic release against grapevine trunk diseases

Antagonistic fungi such as Trichoderma reesei are promising alternatives to conventional fungicides in agriculture. This is especially true for worldwide occurring grapevine trunk diseases, causing losses of US$1.5 billion every year, at which conventional fungicides are mostly ineffective or prohibited by law. Yet, applications of Trichoderma against grapevine trunk diseases are limited to preventive measures, suffer from poor shelf life, or uncontrolled germination. Therefore, we developed a mild and spore-compatible layer-by-layer assembly to encapsulate spores of a new mycoparasitic strain of T. reesei IBWF 034-05 in a bio-based and biodegradable lignin shell. The encapsulation inhibits undesired premature germination and enables the application as an aqueous dispersion via trunk injection. First injected into a plant, the spores remain in a resting state. Second, when lignin degrading fungi infect the plant, enzymatic degradation of the shell occurs and germination is selectively triggered by the pathogenic fungi itself, which was proven in vitro. Germinated Trichoderma antagonizes the fungal pathogens and finally supplants them from the plant. This concept enables Trichoderma spores for curative treatment of esca, one of the most infective grapevine trunk diseases worldwide.