Outcrossing in the homothallic oomycete, Pythium ultimum, detected with molecular markers (original) (raw)
Abstract
The oomycete Pythium ultimum is homothallic, thus a single isolate completes the sexual stage in pure culture. It has been generally assumed that homothallic oomycetes are predominantly inbreeding. In P. ultimum, antheridia occasionally develop from hyphae not directly connected to the oogonium and appear to participate in fertilization, suggesting a possible mechanism for outcrossing. We have used molecular markers to confirm that outcrossing can occur between isolates of P. ultimum. Genetic markers based on randomly amplified polymorphic DNA (RAPD) and restriction fragment length polymorphisms (RFLP) were used to distinguish isolates in a collection of P. ultimum. Two isolates displaying a high level of polymorphism were mixed and placed on media which allows the development of the sexual stage. RAPD markers were used to screen single oospore progeny to identify potential hybrids between the two parental isolates. Subsequent self-fertilization of one putative F1 yielded a F2 population which demonstrated segregation and independent assortment of RAPD and RFLP markers. A similar strategy was used to show that an isolate which is incapable of producing oospores in pure culture can outcross when mixed with a homothallic isolate. These results suggest that other homothallic oomycetes may be capable of outcrossing, and sexual reproduction may, therefore, play an important role in the generation of variation in homothallic oomycetes.
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References
- Adaskaveg JE, Stanghellini ME, Gilbertson RL, Egen NB (1988) Mycologia 80:665–672
Google Scholar - Bell G (1982) The masterpiece of nature: the evolution and genetics of sexuality. University of California Press, Berkeley, California
Google Scholar - Bernatzky R, Tanksley SD (1986) Genetics 112:887–898
Google Scholar - Buchko J, Klassen GR (1990) Curr Genet 18:203–205
Google Scholar - Campbell WA, Hendrix FF (1967) Mycologia 59:274–278
Google Scholar - Forster H, Oudemans P, Coffey MD (1990) Exp Mycol 14:18–31
Google Scholar - Gallindo J, Gallegly ME (1960) Phytopathology 50:123–128
Google Scholar - Hendrix FF, Campbell WA (1968) Mycologia 60:802–805
Google Scholar - Hendrix FF, Campbell WA (1973) Annu Rev Phytopathol 11: 77–98
Google Scholar - Hulbert SH, Ilott TW, Legg EJ, Lincoln SE, Lander ES, Michelmore RW (1988) Genetics 120:947–958
Google Scholar - Maniatis T, Fritsch EF, Sambrook J (1989) Molecular cloning, 2nd edn. Cold Spring Harbor Laboratory, Cold Spring Harbor, New York
Google Scholar - Martin FN (1989) Curr Genet 16:373–374
Google Scholar - Martin FN (1990) Exp Mycol 14:47–56
Google Scholar - Martin FN (1991) Phytopathology 81:742–746
Google Scholar - Martin FN, Kistler HC (1990) Exp Mycol 14:32–46
Google Scholar - McCarten SM, Littrell RH (1970) Phytopathology 60:264–268
Google Scholar - Pratt RG, Green RJ (1971) Can J Bot 49:273–279
Google Scholar - Pratt RG, Green RJ (1972) Can J Bot 51:429–436
Google Scholar - Raper JA (1940) Mycologia 32:710–727
Google Scholar - Raper JA (1960) Am J Bot 47:794–808
Google Scholar - Ribeiro OA (1978) A source book of the genus Phytophthora. J. Cramer Publications, Germany
Google Scholar - Saunders GA (1986) Chloride and other mineral salt requirements for reproduction of Pythium ultimum and other oomycetes. PhD dissertation, University of California, Berkeley
- Shaw DS (1983) The Peronosporales, a fungal geneticists nightmare. In: Buczacki SJ (ed) Zoosporic plant pathogens—a modern prospective. Academic Press, New York, pp 85–121
Google Scholar - Shaw DS (1988) The Phytophthora species. In: Sidhu GS (ed) Advances in Plant Pathology. Academic Press, New York, pp 27–51
Google Scholar - Suiter KA, Wendel JF, Case JS (1983) J Hered 74:203–204
Google Scholar - Tooley PW, Fry WE, Villarreal Gonzalez MJ (1985) J Hered 76:431–435
Google Scholar - Van Der Plaats-Niterink AJ (1981) Monograph of the genus Pythium. Studies in Mycology 21. Institute of the Royal Netherlands Academy of Sciences and Letters, Centraalbureau Voor Schimmelcultures, Baarn, the Netherlands
Google Scholar - Williams JGK, Kubelik AR, Livak KJ, Rafalski JA, Tingey SV (1990) Nucleic Acids Res 18:6531–6535
Google Scholar
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Authors and Affiliations
- Department of Vegetable Crops, University of California, 95616-8746, Davis, CA, USA
David M. Francis & Dina A. St. Clair
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- David M. Francis
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Communicated by O. C. Yoder
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Francis, D.M., St. Clair, D.A. Outcrossing in the homothallic oomycete, Pythium ultimum, detected with molecular markers.Curr Genet 24, 100–106 (1993). https://doi.org/10.1007/BF00324672
- Received: 14 September 1992
- Accepted: 23 December 1992
- Issue Date: July 1993
- DOI: https://doi.org/10.1007/BF00324672