JANG-BAL RYU

Date of Award

Spring 1982

Project Type

Dissertation

Program or Major

Genetics

Degree Name

Doctor of Philosophy

Abstract

Genetic structure of eastern white pine (Pinus strobus L.) was studied with foliar isozymes from 27 provenances by starch gel electrophoresis. Twenty-one loci, five fixed, coding for 12 enzyme systems, including three invariants, were used for this study. Indirect evidence for genetic control of these loci was discussed.

Substantial genetic differentiation within and among provenances was evidenced according to several indices. Based on 12 loci, mean values of average heterozygosity, proportion of polymorphic loci and number of alleles per locus per provenance were .236, .69 and 2.01, respectively. By partitioning of total genetic diversity into its components, interprovenancial allele differentiation amounted to eight percent. Genetic distances among provenances, in general, increased as geographic distances increased. Provenances showing significant correlation between the two distances from one provenance to all the other provenances were clustered.

Allele frequencies at a few loci showed clinal variation with latitude. Central and marginal provenances were identified with cluster analysis, when all alleles were used. Another cluster analysis with frequencies of six alleles chosen for their high contributions to common variance in a factor analysis showed four clusters of provenances. Some ecotypic variation was indicated in the southern Appalachians and in the northern part of the species range.

Relationships among isozyme variables and growth performance were strong at a few loci. High average heterozygosity seems to be favoured in northernmost plantations. Southern provenances with high average heterozygosity showed better growth and less variability for relative height growth in northernmost plantations. Relationships among isozymes and morphological and physiological traits were relatively strong, whereas relationships among isozymes and concentrations of monoterpenes were relatively weaker.

Some possible applications of current study to tree improvement were discussed.

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