© 2004 The American Genetic Association
Inheritance of Resistance to Zucchini Yellow Mosaic Virus and Watermelon Mosaic Virus in Watermelon
From the National Engineering Research Center for Vegetables, Beijing, 100089, P.R. China (Xu); the Department of Horticulture, China Agricultural University, Beijing, 100094, P.R. China (Kang, Shi, and Shen); and the Department of Horticultural Science, North Carolina State University, Raleigh, NC 27695-7609 (Wehner)
Address correspondence to T. Wehner at the address above, or e-mail: todd_wehner{at}ncsu.edu.
High resistance to zucchini yellow mosaic virus–China strain (ZYMV-CH) and moderate resistance to watermelon mosaic virus (WMV) were found in a selection of PI 595203 (Citrullus lanatus var. lanatus), an Egusi type originally collected in Nigeria. Mixed inoculations showed primarily that these two viruses have no cross-protection. This fact may explain the high frequency of mixed infection often observed in commercial fields. When plants were inoculated with a mixture of the two viruses, the frequency of plants resistant to ZYMV was lower than expected, indicating that WMV infection may reduce the ability of a plant to resist ZYMV. We studied inheritance of resistance to ZYMV-CH and WMV, using crosses between a single-plant selection of PI 595203 and the ZYMV-susceptible watermelon inbreds 9811 and 98R. According to virus ratings of the susceptible parents, the resistant parent, and the F1, F2, and BC1 generations, resistance to ZYMV-CH was conferred by a single recessive gene, for which the symbol zym-CH is suggested. The high tolerance to WMV was controlled by at least two recessive genes.