Term of Award

Summer 1995

Degree Name

Master of Science in Biology

Document Type and Release Option

Thesis (restricted to Georgia Southern)

Department

Department of Biology

Committee Chair

Sara Neville Bennett

Committee Member 1

Wayne A. Krissinger

Committee Member 2

Oscar J. Pung

Committee Member 3

James B. Claiborne

Abstract

New osmotic-sensitive mutants, SS-788 and SS-1044, of Neurospora crassa were isolated in the Georgia Southern University Neurospora Genetics Laboratory following UV irradiation of wild type 74 conidia, followed by a filtration concentration procedure in minimal medium containing 3% NaCI. The gross morphology of SS-788 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 morphology of SS-1044 is sparse and pale, unlike the typical osmotic sensitive mutants which are highly pigmented.

The mutants SS-788 and SS-1044 both produced fewer conidia than wild type, while SS-788 produced more conidia than the typical osmotic-sensitive mutants and SS-1044 produced less than the typical osmotic-sensitive mutants. Both mutants grew more slowly on W-M (2% NaCl) and produced less biomass in media supplemented with 2% NaCI. The mutants had longer time periods for germination in both ascospores and conidia and had lower germination percentages on W-M (6% NaCI). Crosses of SS-788 to wild type exhibited a 1:1 segregation of osmotic-sensitive to wild type progeny, indicating that the osmotic trait is under single gene Mendelian control. Preliminary genetic mapping indicated that the mutant was in Linkage Group (LG) VI or LG III. The mutant was found to be linked to the marker strains trp-2, ad-1, del and pan-2. A cross of the double mutant SS-788 del to pan-2 indicated that the mutant was located in the right arm of LG VI distal to the marker del. This is a new linkage group for osmotic-sensitive mutants.

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