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Homologous expression of a mutated beta‐tubulin gene does not confer benomyl resistance on Trichoderma virens
Author(s) -
Mukherjee M.,
Hadar R.,
Mukherjee P.K.,
Horwitz B.A.
Publication year - 2003
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1046/j.1365-2672.2003.02061.x
Subject(s) - biology , benomyl , gene , mutagenesis , aspergillus nidulans , genetics , trichoderma , trichoderma viride , microbiology and biotechnology , mutation , fungicide , botany , mutant
Aims: To clone the beta‐tubulins and to induce resistance to benzimidazoles in the biocontrol fungus Trichoderma virens through site‐directed mutagenesis. Methods and Results: Two beta‐tubulin genes have been cloned using PCR amplification followed by the screening of a T. virens cDNA library. The full‐length cDNA clones, coding for 445 and 446 amino acids, have been designated as T. virens tub1 and T. virens tub2 . A sequence alignment of these two tubulins with tubulins from other filamentous fungi has shown the presence of some unique amino acid sequences not found in those positions in other beta‐tubulins. Constitutive expression of the tub2 gene with a histidine to tyrosine substitution at position 6 (known to impart benomyl/methyl benzimadazol‐2‐yl carbamate resistance in other fungi), under the P gpd promoter of Aspergillus nidulans , did not impart resistance to benomyl. Conclusions: The homologous expression of tub 2 gene with a histidine to tyrosine mutation at position +6, which is known to impart benomyl tolerance in other fungi, does not impart resistance in T. virens. Significance and Impact of the Study: Unlike other Trichoderma spp., T. virens , has been difficult to mutate for benomyl tolerance. The present study, through site‐directed mutagenesis, shows that a mutation known to impart benomyl tolerance in T. viride and other fungi does not impart resistance in this fungus. Understanding the mechanisms of this phenomenon will have a profound impact in plant‐disease management, as many plant pathogenic fungi develop resistance to this group of fungicides forcing its withdrawal after a short period of use.