Date of Graduation

5-2018

Document Type

Thesis

Degree Name

Master of Science in Crop, Soil & Environmental Sciences (MS)

Degree Level

Graduate

Department

Crop, Soil & Environmental Sciences

Advisor

Richard Mason

Committee Member

John Rupe

Second Committee Member

Mary Savin

Third Committee Member

Ehsan Shakiba

Keywords

Fusarium Head Blight, Genome-wide Association Study, Plant Disease Resistance, Wheat Breeding

Abstract

Fusarium head blight (FHB) is a disease of small grains caused by the fungal pathogen Fusarium graminearum. FHB poses potential economic losses and health risks due to the accumulation of the mycotoxin deoxynivalenol (DON) on infected seed heads. The objectives of this study are: 1) evaluate soft red winter wheat (SRWW) lines for resistance to FHB in terms of resistance to initial inoculum (incidence); resistance to spread within the head (severity); resistance to DON accumulation; and resistance to Fusarium damaged kernels (FDK), 2) determine the frequency and effect of known FHB resistance genes and quantitative trait loci (QTL), and 3) identify novel resistance loci using a genome wide association (GWA) approach. From 2014-2017, 360 SRWW breeding lines were evaluated in inoculated misted FHB nurseries in Fayetteville and Newport, AR and Winnsboro, LA (2017 only) in a randomized complete block design. At all locations, lines were sown in two row plots, inoculated with F. graminearum infected corn (Zea mays L.) and overhead misted throughout the months of April and May to provide optimal conditions for FHB infection. In addition to visual ratings and DON analysis, lines were screened with KASP® markers linked to known FHB resistance genes, including Fhb1. The known resistance QTL, Qfhb.nc-2B.1 (Bess), on chromosome 3B was significantly associated with a reduction in incidence, severity, and DON accumulation. Genome wide SNP markers generated through genotype by sequencing (GBS) were used to perform GWA in order to identify marker-trait associations for FHB resistance. The GWA analysis identified 58 highly significant SNPs associated with the four disease traits. The most highly significant SNP was found on chromosome 4A and the minor allele was found to significantly reduce incidence by 1.17%. Results from this study will facilitate the development of SRWW cultivars with improved resistance to FHB.

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