Researchers in Nanking studied six types of mosaic viruses in cucurbits like cucumber and watermelon. They found two groups: one with a wide host range and the other only infecting Cucurbitaceae plants. The virus from cucumber is cucumber mosaic virus, while the one from Luffa is a unique variety of it. The other four viruses are melon mosaic virus, with the one from muskmelon not infecting watermelon.