Isolation and Characterization of a Benomyl-resistant Form of β-Tubulin-encoding Gene from the Phytopathogenic Fungus Botryotinia fuckeliana

Abstract

As an initial step to develop a DNA-mediated transformation system using benomyl resistance as a dominant selectable marker in the phytopathogenic fungus Botryotinia fuckeliana (anamorph, Botrytis cinerea), we have constructed a phage lambda genomic DNA library of a benomyl-resistant strain 91T-1, and a beta-tubulin-encoding gene benA was isolated, cloned and sequenced. Southern blot analysis suggested that a single copy of benA is present in the genome of B. fuckeliana. The benA gene is composed of seven exons which are separated by six introns of 52 to 135 bp. The intron consensus sequences are similar to those of other fungal genes. The deduced amino acid sequence (447 amino acid residues) is highly homologous to those of other fungal beta-tubulin-encoding genes. Comparison of the sequences around codons 198 and 200 in benomyl-resistant and sensitive strains revealed that the benAHR allele from the benomyl-resistant strain 91T-1 contained a mutation at codon 198 from GAG (Glu) to GCG (Ala), which has been correlated with high resistance to benzimidazole fungicides including benomyl in various filamentous fungi.

Part of CIRS Nexus · Curated by Lauren Lowenstein, The Biotoxin Lady