Metabolome and (R)-Mellein Production in Neofusicoccum parvum Strains are Differentially Affected by Grapevine Woody Biomass.

Neofusicoccum parvum is a wood-colonizing fungus that threatens grape production. Its ability to colonize the host may involve the secretion of effector molecules, such as the phytotoxic metabolite (R)-mellein. However, the role of (R)-mellein in disease development and the factors influencing its production are poorly understood. Additionally, how this pathogen alters its metabolome during host interaction remains unclear. Here, we compared the metabolomes and (R)-mellein production of two wild-type N. parvum strains (Bt67 and NpB) and a UV mutant (UV9) cultured with grapevine wood in bioreactors. We found that wild-type strains reduced (R)-mellein production but increased the diversity of secreted metabolites, whereas the UV mutant showed minimal changes when grown with the host tissue. In particular, grapevine wood promoted the production of auxin-related compounds, tyramines, and phenylethanoids. Our findings suggest that N. parvum adapts its metabolite profile in response to host biomass, producing compounds with phytotoxic and antibiotic properties. Finally, (R)-mellein was purified using Centrifugal Partition Chromatography and preparative HPLC, which will aid future research into its role in disease.