Abstract
Two loci (the incompatibility or mating type loci), a and b, govern the life cycle of Ustilago maydis, a fungal pathogen of corn. U. maydis diploids heterozygous at both a and b (a[unk] b[unk]) form mycelial colonies (Fuz+ phenotype), induce tumors, and produce teliospores able to undergo meiosis. We report here the isolation and characterization of nonmycelial (Fuz-) derivatives. These Fuz- diploids have allowed us to examine the requirement of a[unk] and b[unk] in maintenance of filamentous growth and tumor-inducing ability. The Fuz- diploids are of four classes: two are inferred to be homozygous for b (a[unk] b=); the other two are shown to be homozygous for a (a= b[unk]). These observations confirm the requirement for b[unk] and reveal the requirement for a[unk] in filamentous growth. U. maydis is thus like other basidiomycetes that have two loci governing growth of the dikaryotic filament. The mating behavior of the Fuz- diploids indicates that heterozygosity at a or b does not block mating. Although both a= b[unk] and a[unk] b= diploids are nonmycelial, they differ in that a[unk] b= diploids are nonpathogenic, whereas a= b[unk] diploids are pathogenic and produce teliospores able to undergo meiosis. These findings substantiate previous, more limited observations. They demonstrate that ability to induce tumors and produce normal teliospores requires different alleles at b but not at a.
Keywords: corn smut fungus, plant pathology, tumor induction, mating
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- CASSELTON L. A. THE PRODUCTION AND BEHAVIOR OF DIPLOIDS OF COPRINUS LAGOPUS. Genet Res. 1965 Jul;6:190–208. doi: 10.1017/s0016672300004080. [DOI] [PubMed] [Google Scholar]
- Casselton L. A., Lewis D. Compatibility and stability of diploids in Coprinus lagopus. Genet Res. 1966 Aug;8(1):61–72. doi: 10.1017/s0016672300009915. [DOI] [PubMed] [Google Scholar]
- Day P. R., Anagnostakis S. L. Corn smut dikaryon in culture. Nat New Biol. 1971 May 5;231(18):19–20. doi: 10.1038/newbio231019a0. [DOI] [PubMed] [Google Scholar]
- Day P. R., Anagnostakis S. L., Puhalla J. E. Pathogenicity resulting from mutation at the b locus of Ustilago maydis. Proc Natl Acad Sci U S A. 1971 Mar;68(3):533–535. doi: 10.1073/pnas.68.3.533. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Glass N. L., Vollmer S. J., Staben C., Grotelueschen J., Metzenberg R. L., Yanofsky C. DNAs of the two mating-type alleles of Neurospora crassa are highly dissimilar. Science. 1988 Jul 29;241(4865):570–573. doi: 10.1126/science.2840740. [DOI] [PubMed] [Google Scholar]
- HOLLIDAY R. INDUCED MITOTIC CROSSING-OVER IN RELATION TO GENETIC REPLICATION IN SYNCHRONOUSLY DIVIDING CELLS OF USTILAGO MAYDIS. Genet Res. 1965 Feb;6:104–120. doi: 10.1017/s0016672300003979. [DOI] [PubMed] [Google Scholar]
- Holliday R., Halliwell R. E., Evans M. W., Rowell V. Genetic characterization of rec-1, a mutant of Ustilago maydis defective in repair and recombination. Genet Res. 1976 Jun;27(3):413–453. doi: 10.1017/s0016672300016621. [DOI] [PubMed] [Google Scholar]
- Koltin Y., Raper J. R. Dikaryosis: genetic determination in Schizophyllum. Science. 1968 Apr 5;160(3823):85–86. doi: 10.1126/science.160.3823.85. [DOI] [PubMed] [Google Scholar]
- Puhalla J. E. Compatibility reactions on solid medium and interstrain inhibition in Ustilago maydis. Genetics. 1968 Nov;60(3):461–474. doi: 10.1093/genetics/60.3.461. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Roman H, Phillips M M, Sands S M. Studies of Polyploid Saccharomyces. I. Tetraploid Segregation. Genetics. 1955 Jul;40(4):546–561. doi: 10.1093/genetics/40.4.546. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sprague G. F., Jr, Jensen R., Herskowitz I. Control of yeast cell type by the mating type locus: positive regulation of the alpha-specific STE3 gene by the MAT alpha 1 product. Cell. 1983 Feb;32(2):409–415. doi: 10.1016/0092-8674(83)90460-9. [DOI] [PubMed] [Google Scholar]