Biogenic copper oxide nanoparticles from Trichoderma harzianum: a novel approach for managing wheat blast disease

Abstract

Wheat blast, caused by the fungus Pyricularia oryzae Triticum pathotype (PoT), is a devastating disease in South America, Asia and Africa due to limited fungicide effectiveness and a lack of resistant varieties. More recently, it has also been detected in Africa, further exacerbat-ing the global threat posed by this pathogen. In Argentina, it has been detected since 2012, but although no outbreaks have yet been recorded, this pathogen represents an imminent risk due to its presence in the nearby countries. For that, new strategies should be considered for con-trolling the disease and proper surveillance. Nanotechnology can contribute to protecting crops since it offers different mechanisms of action against pathogens. Thus, metallic oxide nanopar-ticles obtained by physicochemical or biogenic methods can act as antimicrobials. This study involved the biosynthesis of green copper oxide nanoparticles (CuONPs) from the fungus Tricho-derma harzianum and evaluation of their ability to reduce fungal mycelium growth and wheat blast disease symptoms in plants. Physicochemical characterization of the CuONPs performed by TEM and EDS showed elongated fibers in shape and an average size of 397 ± 55 nm in length and 124 ± 13 nm in width, as good physico-chemical stability. In vitro and in vivo experiments to evaluate the potential of CuONPs against PoT showed that they were effective in strongly inhibit-ing the mycelial growth of PoT native aggressive strains PY15, PY22 and PY34 by 74, 72 and 67% respectively, at a concentrationof 1000 ppm. Moreover, CuONPs at a concentration of 500 ppm applied as a foliar spray on wheat plants inoculated with PY34 caused a reduction of 95% in disease severity. Further, wheat plants in which their seeds were previously pelletized with 500 ppm CuONPs showed a disease symptom reduction of 90%. These findings confirm that the bio-synthesized CuONPs have a promising antifungal activity, which could be used as protection of wheat against PoT pathogen.