Control of potato late blight by fungal secretome of Trametes versicolor as a biopesticide against Phytophthora infestans

Potato late blight caused by the oomycete Phytophthora infestans is one of the most destructive diseases affecting potato crops worldwide. Managing potato late blight primarily through chemical control is indeed effective but leads to significant health and environmental impacts. For this reason and according to EU directives, sustainable alternatives, including biocontrol agents, are needed. In this work we studied the effect by the cultural filtrate (CF) obtained from the in vitro culture of the ligninolytic basidiomycete Trametes versicolor as biopesticide candidate against P. infestans. CF, as the exo-secretome of the fungus, consists of bioactive molecules with antimicrobial properties, that can be tested in crude form or by separating its components by protein precipitation and polysaccharide purification. By performing in vitro assays, we evaluated the sporangia germination and mycelium growth of P. infestans when CF, the protein or the polysaccharide fractions were added to the media. Moreover, to test the effect of CF against late blight symptoms, we used a detached leaf assay on potato by spraying the plants with CF, infecting them with P. infestans and evaluating the lesions. Interestingly we show that crude CF of T. versicolor is capable to affect the growth of P. infestans, by inhibiting both sporangia germination and mycelium growth, suggesting that some secreted proteins can have antimicrobial activity. Further investigation on the compounds modes of action and in a potato-P.infestans pathosystem will help to assess how to apply crude CF or only bioactive components as biopesticides for integrated pest management strategy of potato disease. 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.