Genome Sequencing and Genome Resources in Model Legumes

Since the completion of the sequencing of the Arabidopsis (Arabidopsis thaliana) genome in 2000, it has become clear that information about the genome of a particular plant species can have dramatic benefits in promoting plant molecular genetics in general. To create a similar situation in legumes, two species with small genomes, Lotus japonicus (Japanese trefoil) and Medicago truncatula (barrel medic), with diploid genomes of 470 to 500 Mb in size, were chosen as references, and genome sequencing was launched at the beginning of this decade (Young et al., 2005). Although the genomes of both species have yet to be fully sequenced, a significant amount of information about their gene structures as well as physical and genetic maps has been made public. In addition, a variety of material resources, such as genomic and cDNA libraries, have been generated during the course of the sequencing work and as a result of sequence analysis. These information and material resources have already contributed to our understanding of genetic systems of biological importance, especially with respect to legume-specific phenomena (Stacey et al., 2006), and are expected to continue to augment research in this field as sequencing continues and is eventually completed for both genomes. Here, we briefly describe the current status of the genome se- quencing of these two model legumes and summarize the information and material resources currently avail- able to facilitate dissemination and exploitation of the resources within the various fields of legume biology.