Term of Award

Spring 1994

Degree Name

Master of Science

Document Type and Release Option

Thesis (restricted to Georgia Southern)

Committee Chair

Sara Neville Bennett

Committee Member 1

Wayne A. Krissinger

Committee Member 2

Oscar J. Pung


A new osmotic sensitive mutant, SS-656, of Neurospora crassa was isolated in the Georgia Southern Neurospora Genetics Laboratory following UV irradiation of wild type 74A conidia, followed by a filtration concentration procedure in minimal medium containing 3% NaCI. The gross morphology of SS-656 resembles that of wild type and is unlike that of the typical osmotic sensitive mutants, which are characterized by deep orange-yellow to dark orange pigmentation and aerial hyphae that are typically close-cropped, aggregated and tend to rupture and exude pigmented cytoplasm (Perkins, et al., 1982). The mutant, SS-656, produces less biomass than wild type and more than the typical osmotic sensitive mutants. The mutant produces more conidia than the typical osmotic sensitive mutants of N. crassa, but fewer than the wild type strain. Examination of the branching pattern of the mutant revealed that it produced the same number of lateral branches at the hyphal tip as the wild type did after 12 hours growth. However, at 26 hours there was a significant difference in the number of lateral branches produced by the mutant and wild type 74A. Crosses of SS-656 to wild type exhibited a 1:1 segregation of osmotic sensitive to wild type progeny, indicating that the osmotic trait is under one gene Mendelian control. Preliminary genetic mapping of SS-656 indicated that the mutant was in Linkage Group I (LG I) or Linkage Group II (LG II) or was in Linkage Group IV (LG IV) or Linkage Group V (LG V). The mutant was found to be linked to the cut tester strain of N. crassa which is in the left arm of Linkage Group IV (LG IV). The mutant SS-656 was found to contain a translocation.

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