Date of Award

Winter 1985

Project Type

Dissertation

Program or Major

Plant Science

Degree Name

Doctor of Philosophy

Abstract

Glycine soja seeds collected from South Korea and Japan were studied for their genetic structure and quantitative variation. Seventy two G. soja seed accessions were examined for genetic variation by gel electrophoresis. Based on a total of 43 loci of 15 enzymes and one protein, an average of 67.4% polymorphism (at 99% level) was observed. The expected heterozygosity is 0.160, and the number of alleles per locus is 2.14. Genetic purity of these seed accessions are very high.

The four natural G. soja populations collected along the Kitakami river, Japan, showed 38.1% polymorphic loci, and the average number of alleles per locus is 1.55. Their overall expected heterozygosity is 0.114 which is much higher than the average observed heterozygosity (0.023). 19.8% of gene diversity of the four natural populations resides among populations and 81.2% within populations. The G(,ST) value calculated from isozyme and protein variation indicates that the four local populations are well differentiated isoenzymatically. The average Nei's genetic distance between each pair of these four populations is 0.044.

Four enzyme loci, Ap, Ti, Lap1 and Pgd2, belong to Linkage Group 9 of soybeans. The gene order of the four loci is Ap-Ti-Lap1-Pgd2, and the recombination frequency between each pair of loci Ap-Ti is 9.41% (+OR-) 1.07%, Ap-Lap1 22.65% (+OR-) 0.73%, Ap-Pgd2 39.78% (+OR-) 0.98%, Ti-Lap1 17.96% (+OR-) 1.33%, Ti-Pgd2 36.85% (+OR-) 1.39%, and Lap1-Pgd2 20.62% (+OR-) 0.99%. Another gene pair, Pgi1-Pgd2, is linked with a recombination frequency of 15.34% (+OR-) 0.74%.

Twelve G. soja accessions were selected based on their latitudinal locations to study their genetic and quantitative variations. The measure of quantitative variation consists of morphological, agronomic, and phenological traits. These 12 seed accessions are significantly different from one another in most of the quantitative traits measured. The principal component analysis shows about 60% of the phenological variation and about 43% of the agronomic variation among these 12 G. soja seed accessions are highly associated with their latitudinal locations. Among three reproduction components only the number of pods per plant is positively correlated with the total yield per plant. The average number of nodules per plant is positively correlated with the percent of 3-seed pods and 4-seed pods. The congruence of population differentiation based on genetic (protein) and quantitative variations of these 12 seed accessions is low.

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