Date of Award

8-2025

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

School

Biological, Environmental, and Earth Sciences

Committee Chair

Dr. Micheal Davis

Committee Chair School

Biological, Environmental, and Earth Sciences

Committee Member 2

Dr. Dmitri Mavrodi

Committee Member 3

Dr. Ebrahiem Babiker

Abstract

Pierce’s disease (PD) and black rot disease cause severe economic losses for grape production under humid and warm conditions. Identifying resistance genes is crucial for controlling these disease by developing resistant cultivars. Muscadine grape (Vitis rotundifolia) cultivar ‘Pam’ has been identified to possess a high level of resistance to diseases. To elucidate the genetic basis of the resistance to the causal pathogens Xylella fastidiosa and Guignardia bidwellii in this cultivar, parents and 141 F1 individuals developed from open pollinated ‘Pam’ were evaluated for two seasons under natural disease pressure. The mapping population was genotyped using genotyping-by-sequencing (GBS) and a genome-wide association (GWAS) approach, based on 80,507 single-nucleotide polymorphism (SNP) markers. Results showed that only 10 genotypes were positive for PD during both seasons, and the average disease severity in the mapping population for black rot ranged from 0.09% to 14.10%. The GWAS analysis, using genotypic data and phenotyping data for black rot, identified major quantitative trait loci (QTL) on chromosome 16. The QTL for resistance was consistent across both years, and one significant SNP marker was consistently detected. Among the genes located in the major QTL interval, nine genes had annotation results, and the most significant candidate gene was found to encode a functional protein for bark storage protein A. The multiple significant markers identified in this study could be utilized to develop markers to assist in marker-assisted breeding programs.

ORCID ID

0000-0002-8421-5951

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