Degree Type

Creative Component

Semester of Graduation

Fall 2019

Department

Agronomy

First Major Professor

Dr. Shuizhang Fei

Degree(s)

Master of Science (MS)

Major(s)

Plant Breeding

Abstract

Many factors play a role in the evolution of agricultural crops and modern plant breeding. I can think of no greater force than that of resistance durability. Resistance durability may be described as the strength of resistance and duration of resistance displayed within a specific crop population against a specific or multiple biotic pest(s) or abiotic stresses.

What genes should be selected to establish sufficient pest resistance? There is no more important step in the process of combining genes than the initial step of choosing and crossing specific donor genotypes for the purpose of integration within a single line. Multiple resistance genes need to be available for this process, which is made possible when plant breeders have access to a wide range of genetic diversity that can be evaluated from large collections of accession data.

The soybean aphid epidemic which occurred in the United States during the early 2000’s as well as the response to the issue as it relates to establishing resistance durability within soybean crops will be the focus of this Creative Component. Additionally, resistance breakthroughs in the battle against alternative soybean pests will be discussed. Parallels may easily be drawn between the aphid epidemic experienced in soybean and the progression of pest problems occurring in other major crops. The goal is to show how breeders utilized pest resistance genes in order to establish increased resistance durability in superior soybean lines by using gene pyramiding. Genotypes carrying single dominant genes have contributed to higher yields by establishing pest resistance, but have quickly become susceptible because of evolving pest biotypes. Gene stacking has diversified the concept of gene integration for crop resistance and also has exposed unexpected results which include continued usefulness of previously susceptible genotypes. Additionally, the use of biotechnology in the form of marker assisted selection (MAS) and genome wide association studies (GWAS) has enhanced the gene pyramiding process. Ultimately, the implementation of MAS, GWAS, and reconstituted use of susceptibility alleles at resistance loci establishes gene pyramiding as superior for establishing durable resistance compared to the use of single dominant genes.

Copyright Owner

Poellnitz, Reginald

File Format

Word

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