Location: Vegetable ResearchTitle: 392291-VDR, a watermelon germplasm line with resistance to Squash vein yellowing virus (SqVYV)-caused watermelon vine decline (WVD)) Author
Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/4/2012
Publication Date: 12/1/2012
Citation: Kousik, C.S., Adkins, S.T., Turechek, W., Webster, C.G., Roberts, P. 2012. 392291-VDR, a watermelon germplasm line with resistance to Squash vein yellowing virus (SqVYV)-caused watermelon vine decline (WVD). HortScience. 47(12):1805-1807. Interpretive Summary: Watermelon vine decline is a serious disease that has plagued watermelon growers for the past several years and has resulted in losses over $60 million in southwest and west central Florida. An ARS scientist in Charleston, SC, in collaboration with others in Florida, developed a watermelon germplasm line “392291-VDR” with resistance to watermelon vine decline (WVD) which is caused by a virus that is spread from one plant to another by insects called whiteflies. This resistant germplasm line can be used by private and public sector plant breeders to develop watermelon varieties and breeding lines with resistance to this dreaded disease. Development of varieties with resistance to watermelon vine decline will help reduce insecticide use and allow watermelon growers to produce a healthy crop of fruit.
Technical Abstract: 392291-VDR (vine decline resistant) is a watermelon (Citrullus lanatus var. lanatus) germplasm line having resistance to watermelon vine decline (WVD) caused by the whitefly transmitted Squash vein yellowing virus (SqVYV). The line is derived from the U.S. Plant Introduction (PI) 392291, after successive screening and pure line selection for six generations (S6) in a greenhouse. The germplasm line 392291-VDR is not completely immune to infection by SqVYV as virus can be detected in inoculated plants by tissue blot nucleic acid hybridization. However, 392291-VDR plants infected with SqVYV do not express vine decline symptoms and decline and die like ‘Mickey Lee’, ‘Crimson Sweet’ and other seedless commercial watermelon cultivars. In addition, inoculated plants of 392291-VDR produce symptomless mature fruit. In greenhouse tests (conducted from 2009 to 2011), plants of 392291-VDR were rated 1-2 on a 1-9 scale (1= no symptoms and 9=plants dead) compared to plants of Crimson Sweet and Mickey Lee that were all rated 9. Plants of 392291-VDR has a runner growth habit, with vine length reaching 6 m. Leaves are lobed (lobate) and 19.3 cm long and 19.3 cm wide at the base. The line is monoecious with almost round fruit that weigh about 3.5 kg. Fruit rind is normal green with dark green stripes. In Charleston, SC, each plant produces approximately 6 fruits. Flesh color in mature fruit ranges from pale yellow to orange yellow with an average Brix value of 6.8 (range 4-9). Since commercial watermelon cultivars with resistance to SqVYV-caused WVD are not yet available, 392291-VDR may be a useful source of resistance in watermelon breeding, even though its fruits are not commercially acceptable.