Talk-all caused by Gaeumannomyces graminis var. tritici (Ggt) is one of the most important root and crown diseases of wheat. In this research, four basidiomycetes isolates as fungal endophytes were isolated from healthy cereal plants and were identified as Coprinopsis urticicola M2, Rhizoctonia endophytica M9, Rhizoctonia zeae M32 and Fomes fomentarius M40 based on phenotypic characteristics and molecular phylogenetic analysis of the ITS rDNA sequences (ITS1-5.8S rDNA-ITS2). Then, their effects as potential biological control agents (BCAs) against Ggt were tested in vitro and greenhouse conditions. All isolates had inhibitory effects on the development of Ggt growth in vitro by dual-culture method with inhibition zones ranging from 39.1% to 54.8%. Volatile antifungal effects were observed for M32 isolate with 23.7% inhibition, followed by the isolate M2 (18.7%). However, culture filtrates of M2 isolate showed maximum inhibition (29.8%). Only two of the four isolates (M2 and M32) had significant effects on controlling take-all in greenhouse conditions. M2 isolate produced IAA and gibberellin, which had the most effect on increasing of growth parameters of wheat plant in greenhouse conditions. M2 isolate was able to colonize the root cortex of wheat seedlings more rapidly compared to pathogen, as assessed by both cultural and microscopic methods. Therefore, its mode of action may depend on the internal root colonization of wheat by C. urticicola M2 and competition for space and nutrient with the Ggt. This is the first research which shows that the C. urticicola M2 could colonize the wheat roots and has great potential to be used as effective biocontrol agent of take-all. Additionally, it can improve growth parameters in wheat under greenhouse conditions. Therefore, the results of this research indicated that C. urticicola M2, due to its ability to colonize the root and crown internal tissues, may provide an advantage as biocontrol agents to be used in the field conditions.
