Intellectual Merit: Root-knot nematodes are microscopic round worms that cause major yield losses to many of the world's crops. Efforts to understand how these pests recognize and interact with their hosts have been hampered by their parasitic life cycle and small size. The goal of the proposed research is to produce an integrated genetic map of the root-knot nematode Meloidogyne hapla. This species was selected because its unusual reproductive mode makes it possible to carry out genetic crosses and to produce large numbers of genetically uniform lines. Nematode strains that differ in attraction to specific plant species and in ability to reproduce on common bean carrying a resistance gene have already been characterized. The segregation of these traits as well as other traits affecting the nematode's ability to infect specific plants and DNA markers will be determined by examination of progeny from genetic crosses. This analysis will be coordinated with a project to sequence the M. hapla genome and will lead to the identification of genes that modulate how a nematode is attracted to and causes disease on specific crop plants.
Broader Impacts: Understanding the biology of these organisms is essential for the development of safer control measures. While the current research will focus on genes involved in host range, it will also establish a basis for other investigations of this complex parasitic interaction as well as for comparison of genome structure among nematode species. Insight into the novel genetic system of M. hapla is likely to stimulate general interest by evolutionary biologists and geneticists working on other organisms. The research will provide a rich source of projects for training students in genetic research approaches, and students at levels from high school to post graduate will participate in the proposed experiments.
