Many viruses infect cucurbits. One of the well-known symptoms is mosaic disease. Those that cause mosaic are cucumber mosaic virus (CMV), squash mosaic virus (SqMV), watermelon mosaic virus (WMV), zucchini yellow mosaic virus (ZYMV) and cucumber green mottle mosaic virus (CGMMV). WMV resistant GM squash was developed many years ago in the United States and it was on the market, but no further information was available by now pertinent to commercial aspect. Usually these viruses are not easily controlled by frequent applications of chemicals that target the insect as carriers of viruses. Therefore, it is necessary to develop commercial varieties possessing resistance against viral diseases. We have developed GM watermelon rootstocks called gongdae, using a coat protein gene of CGMMV as transgene. Those GM watermelon rootstocks showed highly resistant to CGMMV, and have been crossed to get the several BC and T generation. In order to obtain the virus resistant watermelon, watermelon lines were crossed to the selected GM watermelon rootstock. Here, we present the successful watermelon cultivars that show resistance to CGMMV. The resistance must have obtained by transferring the transgene from the GM watermelon rootstock to watermelon line.