Location: Vegetable ResearchTitle: RKVL-318, a root-knot nematode resistant rootstock line for grafted watermelon Author
Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/25/2012
Publication Date: 1/31/2015
Citation: Thies, J.A., Levi, A., Ariss, J. 2015. RKVL-318, a root-knot nematode resistant rootstock line for grafted watermelon. HortScience. 50:141-142.
Interpretive Summary: Watermelon is an important vegetable crop grown in 44 states in the United States. Following the exclusion of the soil fumigant methyl bromide from the market in the United States under the Montreal Protocol, there has been an urgent need to develop effective agricultural techniques such as grafting to combat soilborne diseases and pests in watermelon, and at the same time to enhance disease and pest resistances in watermelon cultivars. In this study, scientists at the USDA, ARS, U.S. Vegetable Laboratory, Charleston, SC, evaluated a large number of wild watermelon accessions collected in different parts of the world and identified several accessions that show higher resistance to root-knot nematodes which attack the roots of plants and cause severe damage in many different vegetable crops, including watermelon. The scientists selected the most resistant wild watermelon plants, used them to develop root-knot nematode resistant breeding lines, and tested the breeding lines as rootstocks for grafting elite watermelon cultivars. The results of this study showed that the wild watermelon breeding line RKVL 318 can be useful as a rootstock for watermelon, producing higher yields in fields infested with root-knot nematodes, than the commonly used squash, pumpkin, and bottle gourd rootstocks. Also, this breeding line can be used in breeding programs aiming to enhance resistances to soilborne diseases or pests in elite watermelon cultivars. The information and the resistant breeding line developed in this study should be useful for seed company breeders aiming to enhance resistance in elite watermelon cultivars.
Technical Abstract: The Agriculture Research Service, U.S. Department of Agriculture, announces the release of ‘RKVL-318’, a novel germplasm line useful as a rootstock and as a genetic resource for enhancing resistance to root-knot nematodes (RKN) in watermelon cultivars. ‘RKVL-318’ is derived from the wild-type watermelon Citrullus lanatus (Thunb.) Matsum. et Nakai subsp. lanatus var. citroides (Bailey) Mansf. ex Greb. (CLC) that is indigenous to southern Africa. The ‘RKVL-318’ plants are resistant to the southern root-knot nematode (Meloidogyne incognita), peanut root-knot nematode (Meloidogyne arenaria), and Javanese root-knot nematode (Meloidogyne javanica), and are valuable rootstocks for grafted watermelon plants, providing them with considerable yield advantage compared with non-grafted watermelon plants in fields infested with RKN. ‘RKVL-318’ should be useful in breeding programs aiming to develop RKN-resistant rootstocks for grafted watermelon or to enhance RKN-resistance in watermelon cultivars. ‘RKVL-318’ was developed at the USDA, ARS, U.S. Vegetable Laboratory, Charleston, S.C. by Dr. Judy A. Thies, Research Plant Pathologist, and Dr. Amnon Levi, Research Plant Geneticist.