Date of Award
Doctor of Philosophy (PhD)
Plant and Environmental Science
Soybean is an important legume crop worldwide. Plant-pathogenic nematodes are common pests that often rob the plant of optimal performance and, therefore, reduce yield potential. Reniform nematode (Rotylenchulus reniformis) is a soil-borne, plant-parasitic nematode found in a wide range of soil textures in tropical to subtropical environments and is capable of infecting soybean. The objectives of this research were to 1) identify quantitative trait loci (QTL) associated with soybean host suitability to reniform nematode using a breeding population carrying genetic resistance from the soybean genotype Forrest, 2) develop and validate molecular markers for use in identifying reniform nematode resistance in soybean germplasm, and 3) map the transcriptome of two reniform nematode-resistant soybean genotypes 24 hours after inoculation with high levels of reniform nematode. Three QTL regions were identified within the soybean genome associated with host suitability to reniform nematode. Single Nucleotide Polymorphisms (SNPs) were chosen within each of the three regions and a Kompetative Allele-Specific PCR assay (KASP) was designed to test their correlation with the phenotype in 84 soybean genotypes. Results indicate use of these markers provide a 76% rate of accurately calling a resistant/susceptible phenotype in soybean germplasm. The transcriptome study confirms that soybeans can detect reniform nematodes at least 24 hours after exposure. A number of defense-related genes were found differentially expressed in the root tissue, particularly cytochrome P450 genes, which may prove to be useful candidates for gene knock-out treatment to identify their importance in conferring resistance to the host plant. This study identifies several novel regions in the soybean genome that correlate to a host defense response to reniform nematode and are potential targets for use in the development of resistant cultivars.
Wilkes, Juliet Elizabeth Fultz, "Mapping Genetic Resistance to Reniform Nematode (Rotylenchulus reniformis) in Soybean" (2020). All Dissertations. 2740.