Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/13/2015
Publication Date: 1/15/2016
Citation: Levi, A., Harris-Shultz, K.R., Ling, K. 2016. USVL-370, A zucchini yellow mosaic virus resistant watermelon breeding line. HortScience. 51:107-109.
Interpretive Summary: Plant viruses, among them is the zucchini yellow mosaic virus, cause serious economic damage to the watermelon crop in the U.S. and throughout the world and there is a need to develop watermelon varieties resistant to plant viruses. USDA, ARS scientists are evaluating watermelon accessions collected in the wild of Africa for resistance to plant viruses and conducting genetic studies aimed at identifying genes conferring resistance to viruses. The scientists used a watermelon accession resistant to the zucchini yellow mosaic virus in a genetic study and were able to map the gene conferring resistance on the watermelon genome. Using a procedure known as ‘marker assisted selection’, the scientists incorporated the gene conferring resistance to the mosaic virus into the genome of the principle American watermelon heirloom cultivar ‘Charleston Gray’. The mosaic virus-resistant line developed in this study is named ‘USVL-370’. This line should be useful for seed company breeders and university researchers seeking to enhance zucchini yellow mosaic virus resistance in elite watermelon cultivars.
Technical Abstract: We report the development of a novel watermelon line ‘USVL-370’ [Citrullus lanatus (Thunb.) Matsum. & Nakai] containing resistance to the zucchini yellow mosaic virus-Florida strain (ZYMV-FL). This breeding line is homozygous for the recessive eukaryotic elongation factor eIF4E allele associated with ZYMV-resistance in Plant Introduction (PI) 595203. USVL-370 was developed through a breeding process that included selection of a ZYMV-resistant F3 plant (PI 595203 x ‘New Hampshire Midget’) crossed to ‘Charleston Gray’ and advanced to BC2F7 using ‘Charleston Gray’ as recurrent parent. The breeding process involved the following stringent selection criteria: 1) phenotype rating of plants inoculated with ZYMV-FL in the greenhouse, 2) an enzyme linked immunosorbent assay (ELISA), and 3) marker assisted selection (MAS) to incorporate the eIF4E allele associated with resistance into the ‘Charleston Gray’ genome background. In field trials in Charleston, SC (2012-2014), USVL-370 plants produced on average 1.4 mature ovular fruits per plant in mid-late season (78-82 days post planting). Mature fruits have an average length and width of 30.51 and 24.71 cm, respectively, and an average weight of 9.14 kg. The rind is light green-gray with an average thickness of 1.0”. The flesh is light red with a sweet flavor and a solid soluble content of 8.6. The USVL-370 should be useful in breeding programs aiming to enhance resistance to ZYMV-FL in watermelon cultivars.