Date of Award

Winter 2014

Project Type

Dissertation

Program or Major

Plant Biology

Degree Name

Doctor of Philosophy

First Advisor

Thomas M Davis

Second Advisor

James E Pollard

Third Advisor

James B Loy

Abstract

Crosses were performed and progeny populations were developed in diploid and octoploid strawberry (Fragaria) species for the purposes of genetic analysis and breeding. A high throughput genotyping platform - the Affymetrix IStraw90® Axiom® strawberry SNP array - was evaluated and employed for these purposes. Phenotyping was conducted with respect to several traits of interest, including flower color, flower and fruit pigment compositions, and verticillium wilt resistance, for the ultimate purpose of identifying marker-trait associations useful in breeding. In the ancestral diploid species Fragaria iinumae, an F2 mapping population was developed from a cross between two accessions previously collected in Hokkaido, Japan. High-throughput genotyping platforms, the IStraw90 SNP Array and Genotyping-by-Sequencing (GBS), were utilized to develop high density linkage maps for F. iinumae. A linkage map based on 21 of the F2 generation plants genotyped on both platforms consists of 4,110 markers, while the second map based 85 F2 plants genotyped on only GBS consists of 895 markers. The linkage maps will used in a parallel research project to anchor an F. iinumae genomic sequence assembly, with the aim of providing an additional reference genome for Fragaria.

A 455 member Closed Pedigree Set of octoploid strawberry plants was developed with diverse flower colors and progress was made on improvement of fruit quality through selection. The range of floral cyanidin and pelargonidin contents determined by HPLC in the progeny exceeded the range of contents of the founding parents, and thus exhibited transgressive segregation. The non-white (NW) flower trait was found to be a completely dominant to white, and no true-breeding, non-white flowered plants were found. The IStraw90 SNP Array was utilized to genotype 41 members of the Closed Pedigree Set and among a total of 5,674 segregating markers, 35 markers predictive of NW flower color were identified on chromosome 5. Additional genotyping will be required to further characterize the marker-trait association for color and to identify quantitative trait loci for hue. Fragaria diploid and polyploid species were phenotyped for verticillium wilt resistance, and disease resistance ratings of the octoploid cultivars were compared to the results of previous published studies and presented in a pedigree format to help identify sources of resistance. The results will be used to identify germplasm for developing populations for high throughput genotyping on the IStraw90 Array for the ultimate goal of identifying marker-trait associations for the purpose of marker-assisted breeding for resistance.

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