title: Construction of chimeric alleles with altered specificity at the b incompatibility locus of Ustilago maydis.
abstract: Multiallelic incompatibility systems found in many fungi and plants function to limit inbreeding by mediating self versus nonself recognition. The plant pathogenic fungus Ustilago maydis has a locus called b that governs incompatibility. Two multiallelic genes, bE and bW, are present at the b locus. Fusion of haploid strains carrying different alleles at bE and bW establishes an infectious dikaryon capable of pathogenesis on maize (Zea mays). Cells carrying a single type of b locus, whether haploid or dikaryotic, are nonpathogenic. To identify sequences within the bE gene that determine allelic specificity, targeted gene replacement was employed to produce a series of chimeras between the b1E and b2E alleles. Incompatibility tests with strains carrying the chimeric alleles identified a 30- to 48-amino acid region responsible for specificity. Suprisingly, the chimeras with recombination points within this region had a specificity different from both parent alleles. Overall, these results define an important domain in bE involved in self versus nonself recognition.
authors.affiliation: Biotechnology Laboratory, University of British Columbia, Vancouver, Canada.
authors.forename: A R
authors.initials: AR
authors.lastname: Yee
authors.forename: J W
authors.initials: JW
authors.lastname: Kronstad
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D002874:Chromosome Mapping; D003433:Crosses, Genetic; D004274:DNA, Recombinant / Q000235:genetics*; D004171:Diploidy; D005800:Genes, Fungal / Q000235:genetics*; D006238:Haploidy; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D014170:Transformation, Genetic; D014588:Ustilago / Q000235:genetics* / Q000472:pathogenicity; D014774:Virulence; D003313:Zea mays / Q000382:microbiology
chemical_list: D004274:DNA, Recombinant