Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/3/1995
Publication Date: N/A
Interpretive Summary: Fusarium wilt is one of the most important diseases that attack melons (cantaloupes, honeydews, etc.). This disease causes major losses to the melon crop in many production areas throughout the world. The most practical method to control the disease is by growing varieties that have genetic resistance to it. In order to develop these resistant varieties, plant breeders must be able to recognize melon plants that have this genetic resistance. In the past, these scientists have had to inoculate melon plants with the fungus that causes the disease and then wait for a month to see which plants were infected. This is a very labor intensive and time-consuming process. Researchers have now identified a genetic marker in melon plants that tells them whether or not that plant is resistant to race 1 of Fusarium wilt. By testing the leaves of melon plants for the presence of this genetic marker, plant breeders can quickly identify resistant plants in their breeding programs. This will enhance the development of melon varieties with resistance to this disease.
Technical Abstract: Resistance to Fusarium oxysporum f. sp. melonis race 1 (Fusarium wilt) in Cucumis melo (muskmelon) is controlled by the dominant gene (Fom 2). Bulked segregant and random amplified polymorphic DNA (RAPD) analyses were employed to identify genetic markers linked to race 1 Fusarium wilt resistance. DNA was isolated from pooled (bulked) susceptible or resistant tplant tissue from a F2 population of susceptible AY x resistant MR-1 cross that was segregating for race 1 resistance. Bulks from resistant plants were composed of both homozygous and heterozygous individuals and also pure homozygous individuals determined by analysis of F3 populations. After screening the DNA from bulked resistant and susceptible plants by PCR with 320 decamer primers, one primer, 5' CCC CTC GAA T 3', produced a 1.6 kb band fragment in the resistant bulks which was absent from the susceptible bulks. Using this primer to screen individual F2 plants, the outcome of 92 2out of 94 individual host/pathogen interactions were correctly predicted. Nine susceptible and three resistant commercial cultivars were also screened with this primer. The 1.6 kb fragment was not amplified using DNA from any of these cultivars. This is the first report of a RAPD marker linked to resistance to Fusarium wilt in cantaloupe.