Evaluation of the extract of pseudopithomyces chartarum to be used as biocontrol agent against phytophthora cinnamomi in Lupinus luteus

Abstract

Endophytic fungi offer promising opportunities for a sustainable disease management in agricultural systems, often related to their secondary metabolites. In this study, the potential of the metabolites produced in vitro by Pseudopithomyces chartarum to protect the forage crop Lupinus luteus against the soil-borne pathogen Phytophthora cinnamomi was evalu- ated in different in vitro and in planta tests. The fungal extracts containing the metabolites were applied by two differ- ent procedures: to seeds by immersion (mycopriming) and to seedlings by spraying (post-emergence). The antagonism between the endophyte fitrates/extracts and the pathogen was studied by dual culture assays and the minimal inhibitory concentration. Other filtrate/extract traits, such as its phytohormones production and nutrient mobilization, were also ana- lyzed. The metabolites contained in the extract were tentatively identified by mass spectrometry. The endophyte’s filtrates and extracts exhibited significant inhibition on the P. cinnamomi growth in vitro. Additionally, seed mycopriming and post-emergence extract application positively influenced seed germination, reduced disease severity, and enhanced several growth parameters in treated seedlings. Auxins and gibberellins production, and phosphate solubilization activity were observed in the endophyte, traits potentially contributing to its biocontrol efficacy. The bioactive compounds ciclo(L-Phe- L-Pro), dihydroabikoviromycin, medelamine A, herniarin, and Piptamine, all with antimicrobial properties, were tenta- tively identified in the extracts, but further research is needed to confirm this identity and to evaluate the extract efficacy under field conditions. This study highlights the potential of certain endophytic fungi as sustainable and environmentally friendly alternatives for a disease management in agriculture