Potential antagonism of some Trichoderma strains isolated from Moroccan soil against three phytopathogenic fungi of great economic importance

In this study, 17 Trichoderma strains were isolated from different soils (crop fields and Argan forests) in Morocco. Purified monospore cultures were identified using molecular methods and tested for their potential antagonism against three phytopathogenic fungi ( Fusarium oxyxporum, verticillium dahlia and rhizoctonia solani ). After DNA extraction, translation elongation factor (tef1) was amplified in extracts of 17 strains, sequenced and compared with their ex-types. As a result, three species were identified among the strains, which clustered in two different subclades of Trichoderma : the species T. afroharzianum , and T. guizhouense belong to the Harzianum clade, while T. longibrachiatum belongs to the Longibrachiatum clade. Investigation of potential antagonistic effects of these strains against the soil-borne phytopathogens F. oxysporum, R. solani and V. dahliae was conducted in a dual culture plate assay, using 17 promising Trichoderma strains that have been selected based on a polymerase chain reaction (PCR) screening approach. In vitro, Trichoderma isolates showed effective antagonistic performance by decreasing soil borne pathogens mycelium radial growth. Trichoderma afroharzianum showed the highest Percentage of Radial Inhibition Growth (PRIG %). The highest PRIG% = 98% was for 8A2.3 isolate against R. solani and the lowest PRIG%= 67% for T9i10 against F. oxysporum . On the other hand, T9i12, which is T. reesei species, led to a high radial inhibition of pathogens’ mycelium. Keywords: Trichoderma spp , Fusarium oxysporum, Verticillium dahlia, Rhizoctonia solani , antagonistic fungi. Resume Dans cette etude, 17 souches de Trichoderma on ete isolees a partir d’echantillons du sol de differentes origines (champs et foret d’arganier). Les especes ont ete identifiees par la caracterisation moleculaire des cultures monospores des isolats de Trichoderma et leur potentiel d’antagonisme a ete evalue contre trois champignons phyto-pathogenes telluriques ( Fusarium oxyxporum, verticillium dahlia et rhizoctonia solani ). Apres l’extraction de l’ADN, le facteur d’elongation et de traduction tef1 a ete utilise comme marqueur moleculaire pour amplifier, sequencer et par la suite caracteriser les 17 souches qui ont ete comparees avec leur ex-types deja references. Par consequent, l’identification moleculaire par tef1 a permis la caracterisation de trois especes de Trichoderma a savoir T. afroharzianum, et T. guizhouense appartenant a la branche Harzianum , et T. longibrachiatum appartenant a la branche Longibrachiatum . Les 17 isolats candidats ont ete selectionnes par une methode de criblage basee sur la PCR (polymerase chain reaction). L’evaluation du potentiel antagoniste des souches de Trichoderma contre les champignons phytopathogenes telluriques ( F. oxysporum, R. solani et V. dahliae ) a ete realisee par la methode de confrontation sur boites de petrie. L’etude in vitro de l’activite antagoniste par le «Pourcentage of Radial Inhibition Growth» (PRIG %) a permis de suivre l’evolution de la croissance radiale du mycelium des differents champignons phytopathogenes. Le pourcentage le plus eleve (PRIG% = 98%) a ete observe pour la confrontation entre l’isolat 8A2.3 et R. solani et le pourcentage le plus faible (PRIG% = 67%) a ete observe pour la confrontation entre l’isolat T9i10 et F. oxysporum . D’un autre cote, T9i12 qui est un isolat de l’espece T. reeseia a engendre une inhibition elevee de la croissance radiale du mycelium des differents pathogenes. Mots cles: Trichoderma spp , Fusarium oxysporum, Verticillium dahlia, Rhizoctonia solani , champignons antagonistes.