Genetic Analysis of Root-knot Nematodes

University Of California-Davis, Davis CA

Investigators

Abstract

Root-knot nematodes are tiny, parasitic worms that infect a wide range of plants and cause major yield losses to the world's crops. Changes to the plant after infection include the formation of galls or root-knots on root systems. Complex molecular signaling between the host and parasite mediates this interaction. Analysis of the roles of the nematode's genes in causing root galling and crop loss has not been possible because of the lack of genetic analysis of the nematode and the lack of knowledge of nematode's genome structure. A major constraint has been that several species of nematodes do not reproduce sexually, making genetic analysis very difficult. However, isolates of the nematode species, Meloidogyne hapla, do reproduce sexually, making this species an excellent model to gain information on what genes in the nematode are responsible for its destructive properties. The goal of the current research is to establish a genetic system for M. hapla. Nematode strains with differences in DNA markers and in ability to reproduce on particular plant lines have already been identified. In this study, the inheritance of ability to reproduce on a wild potato isolate with the gene Rmc1 will be investigated. A protocol to carry out controlled genetic crosses will be developed and segregation of DNA markers will be monitored. Segregation of markers and virulence in the presence of Rmc1 will be assessed to initiate a genetic linkage map. A DNA library representing the entire M. hapla genome will be produced. DNA hybridization to nematode chromosomes will be carried out to aid in determining the genome structure. The linkage map and markers will be a resource for cloning nematode genes associated with ability to parasitise different plant species. Information gained from these studies will facilitate understanding of mechanisms by which parasitic nematodes circumvent plant resistance genes and may lead to environmentally safer means of nematode control in agriculture.