Biocontrol of potato late blight by Trametes versicolor fungal extract with antimicrobial properties

Potato late blight is a devastating disease affecting cultivated potato (Solanum tuberosum) and caused by the oomycete Phytophthora infestans. The use of biocontrol agents and plant resistance inducers are sustainable and alternative ways to fungicides to contrast the disease even at field level. In this study, we tested the effect against potato late blight of the cultural filtrate (CF) derived from the liquid culture of the lignin degrading basidiomycete Trametes versicolor, that we have already employed for its antioxidant and antimicrobial properties. CF is composed of exopolysaccharides (specifically, Tramesan), lipids, peptides, etc.; the mode of action of the singular components is currently undergoing studies. To evaluate if CF can be used to counteract P. infestans in potato, we conducted in vitro and in planta assays, by growing the pathogen in presence of the extract and analyzing plant defense responses (via HPLC-MS/MS and RT-qPCR). Interestingly we show that the CF of T. versicolor can affect the growth of P. infestans, inhibiting mycelium development and sporangia germination. Instead, when used as a biostimulant in potatoes, it did not enhance significant defense responses prior the infection, although it did not show any phytotoxic effect. Further studies in a potato-P.infestans pathosystem will help to confirm whether CF can be used as natural antimicrobial more than a priming agent and be implemented in field trials for sustainable potato disease management. This work was supported and funded by the project SOS TATA SVILUPPO DI NUOVE TECNOLOGIE NELL'AGRICOLTURA DI PRECISIONE PER LA PRODUZIONE SOSTENIBILE DI GENOTIPI DI PATATA CON ELEVATE QUALITÀ NUTRIZIONALI, n. F/200088/01-03/X45, Asse 1, azione 1.1.3. del Programma Operativo Nazionale «Imprese e Competitività» 2014-2020 FESR.