Trichoderma viride Controls Macrophomina phaseolina through its DNA disintegration and Production of Antifungal Compounds

Abstract

Macrophomina phaseolina is a highly destructive pathogen of more than 500 plant species. It is difficult to eradicate it through chemical means as no patented fungicide is available against this pathogen. Biological control is the possible alternative method for its suitable management. The present study was carried out to evaluate the biocontrol potential of five Trichoderma spp. against M. phaseolina and the possible mechanisms of action. Identifications of all the Trichoderma spp. viz. T. hamatum, T. harzianum, T. koningii, T. longipile and T. viride were confirmed on molecular basis by using two universal primer pairs namely ITS and EF1. Their biocontrol potential was evaluated in dual culture plate method where T. viride showed the highest inhibitory efficacy (63%) against M. phaseolina. T. koningii, T. hamatum and T. longipile showed akin effects by arresting growth of the pathogen by 46-47% followed by T. harzianum (28%). To find out the mechanisms of action, secondary extrolites of the best biocontrol fungus T. viride were tested against the pathogenic genomic DNA where all the concentrations partially degraded DNA bands after 24 h of incubation and a complete DNA band disappearance was noted after 48 h incubation. In addition, T. viride culture filtrates were partitioned with chloroform and ethyl acetate and subjected to GC-MS analysis for identification of potential antifungal constituents. The most abundant identified volatile compounds in the two organic solvent fractions were 9,12-octadecadienoic acid (Z, Z)- (44.54%), n-hexadecanoic acid (24.02%), hexadecanoic acid, 2-hydroxy-1-(hydroxymethyl) ethyl ester (14.25%), 9-tricosene, (Z)- (10.43%) and [1,1‘-bicyclopropyl]-2-octanoic acid, 2‘-hexyl-, methyl ester (10.43%). To conclude, T. viride was the best biocontrol agent against M. phaseolina and acts against the pathogen by DNA disintegration and production of antifungal secondary metabolites.