Abstract
Teflon film surfaces are highly conducive to the formation of infection structures (appressoria) in the plant pathogenic fungus, Magnaporthe grisea. We have utilized Teflon films to screen and select for mutants of M. grisea that are defective in appressorium formation. This approach and several others yielded a group of 14 mutants with a similar phenotype. All the mutant strains make abnormally shaped conidia and appressoria. When two mutant strains are crossed, abnormally shaped asci are formed. Ascus shape is normal when a mutant strain is crossed with a wild-type strain. Despite dramatic alterations in cell shape these strains otherwise grow, form conidia, undergo meiosis, and infect plants normally. This mutant phenotype, which we have termed Smo(-), for abnormal spore morphology, segregates in simple Mendelian fashion in crosses with wild-type strains. Some ascospore lethality is associated with smo mutations. In genetic crosses between mutants, smo mutations fail to recombine and do not demonstrate complementation of the abnormal ascus shape phenotype. We conclude that the smo mutations are alleles of a single genetic locus and are recessive with regard to the the ascus shape defect. Mutations at the SMO locus also permit germinating M. grisea conidia to differentiate appressoria on surfaces that are not normally conducive to infection structure formation. A number of spontaneous smo mutations have been recovered. The frequent occurrence of this mutation suggests that the SMO locus may be highly mutable.
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Selected References
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- Hamer J. E., Howard R. J., Chumley F. G., Valent B. A mechanism for surface attachment in spores of a plant pathogenic fungus. Science. 1988 Jan 15;239(4837):288–290. doi: 10.1126/science.239.4837.288. [DOI] [PubMed] [Google Scholar]
- Hoch H. C., Staples R. C. Visualization of actin in situ by rhodamine-conjugated phalloin in the fungus Uromyces phaseoli. Eur J Cell Biol. 1983 Nov;32(1):52–58. [PubMed] [Google Scholar]
- Hoch H. C., Staples R. C., Whitehead B., Comeau J., Wolf E. D. Signaling for growth orientation and cell differentiation by surface topography in uromyces. Science. 1987 Mar 27;235(4796):1659–1662. doi: 10.1126/science.235.4796.1659. [DOI] [PubMed] [Google Scholar]
- Parsons K. A., Chumley F. G., Valent B. Genetic transformation of the fungal pathogen responsible for rice blast disease. Proc Natl Acad Sci U S A. 1987 Jun;84(12):4161–4165. doi: 10.1073/pnas.84.12.4161. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Srb A. M., Basl M., Bobst M., Leary J. V. Mutations in Neurospora crassa affecting ascus and ascospore development. J Hered. 1973 Sep-Oct;64(5):242–246. [PubMed] [Google Scholar]