Isolation, morpho-physiological and molecular characterization, phylogenetic analysis  of Trichoderma asperellum in Bangladesh

Abstract

The experiment was conducted at four laboratories, Bangladesh Agricultural University, Mymensingh to identify T. asperellum and its characterization was obtained from the rhizosphere of 49 different crops in 109 different locations in Bangladesh. Fifteen isolates of 88 isolates in T. asperellum were characterized on morphological and physiological features. TR27 and TR45 were grown and sporulated at 40°C except all the isolates of 35°C. As the increasing pH value mycelial growth of all the isolates was reduced. Molecular characterization in four isolates of (TR27) Sadar, Moulvibazar (Rice), (TR45) Sadar, Mymensingh (Sweet gourd), (TR70) Chapra, Chapai Nawabganj (Sesame) and (TR85) Nayanpur, Lalmonirhat (Maize) were studied at ITS and TEF region nucleotide sequencing among 15 isolates of T. asperellum, and the morphological characterization at ITS and tef1 nucleotide sequencing was assimilated with molecular characterization. Isolates of TR45, TR70 and TR85 were found with 98% homology and TR27 exhibited 88% against their respective closest isolate. Isolates of TR27 and TR85 marked their respective nearest homology (96%), while TR45 showed 99%, and 93% homology was signified with TR70 in TEF sequences. Isolates of TR45, TR70 and TR85 were identified as T. asperellum of 100% bootstrap value and TR27 isolate was also recognized with 72% bootstrap value in the phylogenetic tree. In phylogenetic analysis, tef1 extended better differentiation among the Trichoderma isolates within and among the groups of closely related species than rDNA of the ITS region in reflecting wider variability in the isolates while a higher transversion ratio and evolutionary divergence were defined.