Bacterial fruit blotch (BFB) of cucurbits caused by Acidovorax citrulli has the potential to devastate production of watermelon and other cucurbits. Despite decades of research, no watermelon germplasm has been found with immunity, and only a few sources with various levels of resistance have been identified. The genetic basis of resistance was not known and is complicated by low heritability and strong environmental influence. CucCAP researchers identified a BFB resistant citron melon (Citrullus amarus) and used it for QTL mapping. Six QTL were identified, each explain between 5 and 15% of the variation in resistance. This study represents the first identification of QTL associated with resistance to A. citrulli in any cucurbit.
An abstract for QTL mapping of resistance to bacterial fruit blotch in Citrullus amarus was first published online in February 2019. CucCAP scientists Sandra E. Branham and W. Patrick Wechter conceived and conducted this project with co-authors Amnon Levi and Melanie L. Katawczik at the USDA-ARS Vegetable Research Lab in Charleston, SC. The article can be found in the May 2019 issue of the online journal, Theoretical and Applied Genetics International Journal of Plant Breeding Research.