Location: Vegetable Research
Project Number: 6080-22000-031-058-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 15, 2026
End Date: Aug 31, 2028
Objective:
Overall objective of the project is to characterize the genetics of resistance to whitefly-transmitted virus in watermelon and other cucurbits. Specific objectives include:
1. Characterize genetics of resistance in watermelon to Squash vein yellowing virus (SqVYV).
2. Characterize genetics of resistance in watermelon to Cucurbit leaf crumple virus (CuLCrV).
3. Develop statistical and machine learning (ML/AI) models for genomic selection and genomic Prediction.
Approach:
he primary goal of this project is to enhance resistance to two major whitefly-transmitted viruses (Squash vein yellowing virus & Cucurbit leaf crumple virus) through phenotyping and Quantitative Trait Loci (QTL) mapping of a recombinant inbred line (RIL) population, to eventually develop watermelon cultivars for the American growers make a profitable crop. Whiteflies and whitefly-transmitted viruses have become a major constraint to vegetable production in United States. Since its introduction to United States in 1985, the sweet potato whitefly has rapidly spread across the southeastern region. Growers and stakeholders incur revenue losses not only from managing this pest, but also from the viruses it transmits. In the past few years, whitefly-transmitted viruses have reduced yields in more than 10,000 acres across Florida, South Carolina and Georgia. Simply put, a single whitefly can transmit these viruses, hence management through vector control is difficult. Consequently, host-plant resistance represents the most sustainable strategy to manage these viruses. Mixed infections of SqVYV and CuLCrV have been reported across southeast including South Carolina, Georgia, Florida, leading to significant yield losses. Recently, 81% of watermelon samples collected in Colquitt, Georgia were infected with CuLCrV, while in South Florida 23% of the watermelon samples had SqVYV. In Florida, few large watermelon producers have halted production due to these viruses. In the past few years, we developed 392291-VDR as a stopgap measure for SqVYV, but the harvested fruits are yellow and inedible. Through the proposed project we aim to identify lines with resistance to SqVYV and CuLCrV with red-flesh fruits. Simultaneously, Quantitative trait loci (QTL) mapping and Kompetitive Allele Specific Polymorphic (KASP) markers will allow us to effectively identify and transfer resistant alleles strengthening watermelon production against two important cucurbit viruses in southeastern United States. Techniques for phenotyping watermelon for resistance SqVYV and CuLCrV have been well developed. Genotype data for the RIL lines will be developed by whole genome resequencing (WGRS) of the individual RIL lines (20X). Chromosomal regions involved in resistance to the two viruses will be identified by QTLseq and KASP markers will be developed. Statistical and Machine Learning (AI/ML) based genomic slection models will be developed using genomic and phenotype data. Deliverables will include advanced watermelon breeding lines with resistance to two whitefly-transmitted viruses (WTVs) i.e., SqVYV and CuLCrV and red flesh with high sugars will be released. Genomic regions conferring resistance to these viruses will be identified and KASP markers as proxy for these resistant genomic regions will be developed. Breeding lines and KASP markers will be extremely valuable to University, Federal scientists and seed industry for developing resistant commercial cultivars and reducing crop losses due to these two major whitefly-transmitted viruses in watermelon growing regions.