RT Journal Article SR Electronic(1) A1 Cooley, R. Neil A1 van Gorcom Robert, F. M. A1 van den Hondel Cees, A. M. J. J. A1 Caten, Christopher E.YR 1991 T1 isolation of a benomyl-resistant allele of the β-tubulin gene from Septoria nodorum and its use as a dominant selectable marker JF Microbiology, VO 137 IS 9 SP 2085 OP 2091 DO https://doi.org/10.1099/00221287-137-9-2085 PB Microbiology Society, SN 1465-2080, AB We have developed a homologous transformation system for the wheat-pathogenic fungus Septoria nodorum based on a benomyl-(MBC-) resistant allele of the β-tubulin gene. The β-tubulin gene was isolated by heterologous hybridization from a cosmid library prepared from an MBC-resistant mutant. Cosmids carrying the gene conferred MBC resistance when introduced into a sensitive strain, demonstrating that resistance to MBC fungicides in S. nodorum may be determined by the β-tubulin gene. This MBC resistant allele of the β-tubulin gene (tubAR) was subcioned into pUC18 and used as a dominant selectable marker for transformation of wild-type sensitive strains. Transformants arose at frequencies of approximately 5 per μg of DNA, were integrative in nature and were mitotically stable. Some transformants showed a marked reduction in vigour, both in the presence and absence of MBC; this is thought to arise from overproduction of β-tubulin. The S. nodorum tubAR gene also conferred MBC resistance on the related species Leptosphaeria maculans, a pathogen of Brassica, following its introduction by cotransformation. Probing digested S. nodorum DNA with tubAR at low stringency revealed only a single β-tubulin gene. We anticipate that tubAR will prove a useful tool for the investigation of the pathogenicity of S. nodorum and other fungi., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-137-9-2085