Date of Award
12-2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Plant and Environmental Science
Committee Chair/Advisor
Dr Sandra Branham
Committee Member
Dr Patrick Wechter
Committee Member
Dr Amnon Levi
Committee Member
Dr Richard Boyles
Committee Member
Dr William Bridges
Abstract
Watermelon and cantaloupe are two widely consumed cucurbits, but their acreage in the United States reduced by nearly 50% in last two decades. Fusarium wilt caused by a soil borne pathogen Fusarium oxysporum f. sp. niveum(Fon) race 2 is a major limiting factor in watermelon production as it reduces yields by 80%. Grafting watermelon plants onto the root stock of wild, disease-resistant varieties like ‘Carolina Strongback’ is the best strategy to manage Fon race 2. Though effective, this approach increases production costs.
Part of this dissertation focused on finding more sustainable, cost-effective solutions to control Fusarium wilt in Watermelon. We screened 127 wild watermelon accessions to identify the sources of resistance to Fusarium wilt caused by Fon race 2. Genome-wide association study identified four genomic regions Fon race 2 resistance. QTL mapping technique mapped the Fusarium wilt race 2 resistance regions of watermelon genome with a population developed between resistant and susceptible parent USVL246-FR2 and USVL114, respectively. This led to the development of simple high-throughput DNA-based tools, called markers. Developed markers were thoroughly validated and a set of markers were released to predict the resistance to Fusarium wilt race 2. Plant breeders can use these markers to quickly and accurately identify resistant plants—making the breeding process faster and more efficient.
Delayed female flowering and fruit initiation of watermelon hybrids grafted onto the root stock Carolina Strongback increases crop growth duration. A population varying for days to female flowering and fruiting was evaluated in four field trials. Stable genomic regions altering days to female flowering and fruiting were identified with help of QTL mapping. Two genomic regions influencing flowering time were identified on Chromosome 3. These findings help the development of markers that can be used by geneticists and watermelon breeders to design and develop root stocks with early female flowering habit.
Local production and consumption of cantaloupe experienced a 50% decline in past two decades. This is largely due to food safety concerns linked to its rough netted skin and a loss of fruit flavor over time. Part of this dissertation aimed to develop a smooth-skinned melon—like the French ‘Charentais’ type, that combines rich flavor with resistance to multiple diseases. Several ‘Charentais’ type BC2F4 families were developed by planned crosses and self-pollinations involving flavorful Charentais’, eastern shipper cultivar ‘Topmark’ and disease-resistant lines ‘RIL-206’. Most of melons showed strong resistance to Fusarium wilt and powdery mildew in disease screening tests. Some BC2F4 families outperformed Charentais interms of sweetness, fruit weight and firmness. Further evaluation and selection among the BC2F4 families will lead to the development of ‘Charentais’ type melons for the Southeastern United States.
Recommended Citation
Ganaparthi, Venkata Rao, "Breeding for Disease Resistance in Melon and Watermelon" (2025). All Dissertations. 4166.
https://open.clemson.edu/all_dissertations/4166
Included in
Agronomy and Crop Sciences Commons, Plant Breeding and Genetics Commons, Plant Pathology Commons
Comments
This dissertation presented a comprehensive understanding of Fusarium wilt race 2 resistance genetics in watermelon and developed Charentais type melons for the southeast cantaloupe market.