Antifungal Potential of Trichoderma afroharzianum Metabolites

Abstract

Trichoderma is a fungal genus of undeniable importance for agriculture, whose species being used as biofungicides or even as biofertilizers. The objective of this work was to evaluate the in vitro production of volatile and non-volatile metabolites by five Trichoderma afroharzianum strains active against the phytopathogenic fungi Phaeocytostroma sacchari, Macrophomina phaseolina, Sclerotium rolfsii, Sclerotinia sclerotiorum and Fusarium verticillioides. In the investigation of volatile metabolites production, the technique of overlapping Petri dishes was used while in the non-volatile metabolites bioassay, the technique of incorporation of the filtrates in the potato-dextrose-agar medium was used. For evaluation antifungal effects, the radial mycelial growth of the fungi and the mycelial growth inhibition index (MGI) were used as parameters. All Trichoderma isolates produced volatile metabolites capable of inhibiting, to some degree, the growth of the phytopathogens in question. Inhibition by volatile metabolites of M. phaseolina ranged from 20.02 to 29.32%; S. sclerotiorum between 28.46 and 51.19%; S. rolfsii from 40.0 to 51.47%; P. sacchari from 51.29 to 56.91% and for F. verticillioides between 26.77 and 40.92%. Regarding non-volatile metabolites did not inhibit the growth of M. phaseolina, while for S. sclerotiorum the MGI varied from 11.76 to 52.94%, S. rolfsii between 7.84 and 62.74%, P. sacchari, from 0.0 to 33.72% and for F. verticillioides between 16.47 and 31.37%. The present study presents a better understanding of the mechanism of action of Trichoderma isolates against plant pathogenic fungi, observing an isolate-specific inhibitory activity.