Degree Name

MS (Master of Science)

Program

Biology

Date of Award

8-1995

Committee Chair or Co-Chairs

Foster Levy

Committee Members

David Benner, Lee Pike

Abstract

Prior studies of reproductive isolation among three varieties of Phacelia dubia have found that gene loci encoding isozymes of glutamate oxaloacetate transaminase (GOT) were associated with hybrid sterility. In the first part of this study, I generated three-way hybrids to determine if the genetic or chromosomal region linked to GOT encoding loci has major effects on hybrid sterility and if any observed effects were similar in different genetic backgrounds. In three-way crosses, F1 hybrids of two varieties were crossed to a third variety. Fertilities of three-way hybrids were estimated and their GOT genotypes were ascertained by starch gel electrophoresis. A significant correlation between fertility and GOT genotype was observed in most crosses. In addition, three flower characteristics of three-way hybrids (filament length, petal width and petal length) were associated with pollen fertility and GOT genotype. These correlations were attributed to pleiotropic effects. The genetic causes of hybrid sterility could be genie (due to specific gene interactions) or chromosomal (caused by differences of gene arrangements on the chromosomes among three varieties).

In order to distinguish the genetic causes of hybrid sterility, more genetic markers associated with sterility and/or GOT loci have to be identified. After mapping these markers, gene rearrangements involving chromosomes among three varieties and the position of possible translocations can be determined. In this research, I used the polymerase chain reaction to locate a DNA marker that was associated with sterility in three-way hybrids.

Document Type

Thesis - unrestricted

Copyright

Copyright by the authors.

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