Genetics and genomics of root symbiosis

Model genetics and genomics have been developed as tools for studying the t hird largest family of flowering plants, the Leguminosae, which includes im portant crop plants. Functional genomics strategies for the global analysis of gene expression, the elucidation of pathways and reverse genetics are e stablished. These approaches provide new possibilities for investigating rh izobial as well as mycorrhizal endosymbiosis. Plant genes with central func tions in these mutualistic interactions have been identified by positional cloning and gene tagging. With progress in Lotus japonicus genome sequencin g, which was recently initiated by Japanese researchers, comparative genomi cs will contribute to our understanding of symbiosis, pathogenesis and the evolution of plant genomes.