Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)




Starch gel electrophoresis has been used extensively in genetic studies of numerous plant species and to determine inheritance patterns and linkage relationships of individual enzyme loci. There has been only limited use of electrophoretic techniques to study genetic relationships and population structure in annual sunflower, Helianthus annuus. The objectives of this study were to detail the inheritance of additional enzyme loci in sunflower and to use enzyme loci to determine levels of outcrossing in an open-pollinated sunflower population over a three year period. In 1957, Hunter and Markert developed the methods currently in use for starch gel electrophoresis of plant proteins by combining histochemical staining techniques with the starch gel electrophoresis methods developed by Smithies in 1955. Refinements in electrophoretic techniques have resulted in an ability to gather large quantities of genetic information rapidly and efficiently. Electrophoresis is the movement of charged protein molecules in solution in an electric field. The size and shape of the molecule, its net electrical charge, and the sieving properties of the electrophoretic media affect the migration rate and separation of the proteins being assayed. After staining, the resulting banding patterns can be used to identify the genotypes of individuals. The term "isozyme" describes different molecular· forms of the same enzyme, and the term "allozyme" is used to describe different proteins produced by allelic forms of the same locus. A locus is considered to be monomorphic if only one allozyme phenotype is observed, and polymorphic if two or more allozyme phenotypes are observed. It is important to understand the inheritance and linkage relationships of enzyme marker loci in order to accurately utilize electrophoretic data for detailed genetic studies of a plant species. The formal genetics of only nine such enzyme loci of sunflower have been reported. Electrophoresis has been utilized to study mating systems in a number of plant species. The mating system plays an important role in determining the genetic composition of populations. Precise estimates of self-fertilization versus cross-fertilization are necessary to determine the forces that change gene and genotypic frequencies from generation to generation in open-pollinated populations. The outcrossing rates occurring in open-pollinated oilseed sunflower populations have not been precisely estimated. The purpose of this study was twofold. The first objective was to determine the inheritance and linkage relationships of enzyme marker loci in sunflower. The second purpose was to determine the level of self-pollination versus cross-pollination in an open-pollinated sunflower population, Helianthus Germplasm Pool II, over three years of testing, and to determine if the frequency of enzyme alleles changed during the study.

Library of Congress Subject Headings

Sunflowers -- Genetic engineering

Sunflower -- Breeding




Number of Pages



South Dakota State University