Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/23/2015
Publication Date: 8/30/2016
Citation: Wechter, W.P., Katawczik, M.L., Farnham, M.W., Levi, A. 2016. Watermelon germplasm lines USVL246-FR2 and USVL252-FR2 tolerant to fusarium oxysporum f. sp. niveum race 2. HortScience. 51(8):1065-1067.
Interpretive Summary: Fusarium wilt of is one of the most serious soil-borne diseases of watermelon throughout the world. A particularly aggressive race of this pathogen, race 2 has caused significant losses in the U.S. Currently, no commercial watermelon cultivars are available with significant resistance to race 2. ARS scientists at the U.S. Vegetable Laboratory in Charleston, SC, identified two wild watermelon plant introductions with high levels of tolerance to the wilting pathogen. Individuals from these plant introductions were further developed under disease-based tolerant assays to generate two highly tolerant lines, USVL246-FR2 and USVL252-FR2. These two new lines have been met with high demand from numerous watermelon breeders working for national and international seed companies with interest in developing Fusarium wilt race 2 tolerant varieties, as well as, rootstock developers in the emerging grafted watermelon market, and university researchers working in the realm of genetics and genomics of Fusarium wilt resistance.
Technical Abstract: Two improved germplasm lines of wild watermelon (Citrullus lanatus var. citroides) designated USVL246-FR2 and USVL252-FR2 were released in 2012 by the Agricultural Research Service of the U.S. Department of Agriculture (Wechter et al. 2012). These lines are each highly uniform for growth characteristics, fruit size, and fruit shape. In both greenhouse and field tests, these lines also exhibit high levels of tolerance to the phytopathogen Fusarium oxysporum f. sp. niveum race 2 (Fon-R2) when compared to the watermelon cultivars Charleston Gray, All Sweet, Calhoun Gray and Sugar Baby (all Citrullus lanatus var. lanatus). In addition, they have shown higher vigor and equal or higher tolerance levels to Fon-R2 than PI 296341-FR, an improved C. lanatus var. citroides germplasm line which has been reported previously as resistant to Fon-R2.