Date of Award

Winter 12-18-2020

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Plant Science

Advisor

Gregory A. Porter

Second Committee Member

Ek Han Tan

Third Committee Member

Michael E. Day

Additional Committee Members

Jianjun Hao

Kathleen G. Haynes

Abstract

This study establishes the start of late blight genetic profiles for varieties and clones used as potato breeding material across the United States,and a Mendelian use of marker-assisted selection is employed to estimate allele dosage.

Potato is the fourth most important staple crop worldwide, with both high nutritional and economic values. Breeders seek improvements for many traits related to yield, dry matter, and surface and internal defects. Resistances to several diseases are also desired traits that breeders try to incorporate into their programs. The advent of DNA-based genetic technologies help breeding programs facilitate faster selection, including the use of marker-assisted selection. When specific alleles or linked markers may be present, breeders can test offspring early in the process and eliminate unwanted plant material that does not possess the trait of interest. However, these programs only work when breeders know what genes are in their program. Resistance to late blight, one of the most devastating potato diseases, is graded on a spectrum and facilitated by dozens of resistance genes throughout the Solanum genera. Genes from S. demissum, S. bulbocastanum, S. phureja and others have been introgressed into S. tuberosum, generating late blight resistant varieties like Defender, Yukon Gold, Tollocan, and Missaukee, yet their genotypes are largely unknown. Gene stacking is generally the preferred approach to incorporating gene resistance and is being pursued through trans- and cisgenic biotechnologies. But gene stacking is difficult to achieve through traditional breeding techniques without knowing what genes are present within the resistant cultivars. This study establishes the start of late blight genetic profiles for varieties and clones used as potato breeding material across the United States, as well as offering time-saving methodologies through a multiplex protocol. Additionally, a Mendelian use of marker-assisted selection is employed to estimate allele dosage in breeding clone NY121. This protocol solves a long-standing problem in potato breeding and can be easily utilized for any gene in potato to give an estimate for allele number.

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