Trichoderma as a Biological Nanofactory: Metabolic Control of Silver Nanoparticle Biosynthesis and Activity Against the Grapevine Trunk Pathogen Neofusicoccum parvum

Abstract

Grapevine trunk diseases, particularly those caused by Neofusicoccum parvum, represent a major threat to vineyard productivity and are increasingly difficult to control with conventional fungicides. Green synthesis of silver nanoparticles (AgNPs) using biocontrol fungi offers a promising alternative, but the factors governing the efficiency and bioactivity of biogenic nanoparticles remain poorly understood. Here, three Trichoderma species (T. harzianum, T. asperellum and T. virens) were evaluated as biological nanofactories for AgNP production. Cell-free fungal filtrates were used to synthesize AgNPs, which were characterized by UV–visible spectrophotometry, Dynamic Light Scattering (DLS) and transmission electron microscopy, while fungal redox metabolism was assessed using DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assays and HPLC profiling of extracellular metabolites. AgNPs were tested against two isolates of N. parvum in vitro. The Trichoderma strains differed markedly in nanoparticle yield, size and antifungal activity, with T. harzianum T0 producing the highest amounts of small, well-dispersed AgNPs that exerted a strong fungistatic effect on N. parvum. Nanoparticle production correlated with antioxidant capacity and the abundance of redox-active metabolites. Integration of these parameters into a Fungal Nanofactory Efficiency Index (FNEI) revealed that nanoparticle bioactivity depends on both dose and biological origin. These results demonstrate that fungal metabolism is a key determinant of biogenic nanoparticle performance and identify Trichoderma as a platform for sustainable nanotechnology-based control of grapevine trunk pathogens.