Characterization Of The Two Benomyl-Resistant Mutants Of Magnaporthe Grisea

A transformation vector with the mutated Bml gene from Neurospora crassa as the selectable marker to benomyl and under the transcriptional control of the gpd promoter and terminator from the rice blast fungus, Magnaporthe grisea (isolate 0742), was used to transform M. grisea spheroplasts and two benomyl-resistant transformants (Ml and M2) were obtained. However, southern analysis showed that the resistance of the transformants were not to linked to the vector plasmid. Sequence comparison of the gene encoding β-tubulin from the wild-type and the mutants revealed 3 point mutations at position 56 178 1704 of the coding strand for mutant Ml and 5 point mutations at position 56 899 1040 1389 1704 of the coding strand for mutant M2. These results in the substitution of amino acid in M1, from threonine to alanine (position 352), and in M2, from threonine to alanine (position 107), from lysine to glutamic acid (position 154), from phenylalanine to serine (position 270), from threonine to alanine (position 352). The finding of benomyl-resistant mutation may lead to the development of a new genetic marker for the M. grisea.