Molecular genetics of plants requires short life cycle, small genome size, small plant size, easy transformation, etc. Lotus japonicus is a perennial legume plant grown in Japan. It has features as 2 to 3 months of seed to seed, diploid, self compatible, about 500Mbp of genome size, transformable by Agrobacterium. Lotus has been used worldwide as a model legume, especially in Europe and Japan. It has a possibility of a model plant for mycorrhiza and pathogen interaction, second metabolites and organ development, as well as symbiotic nitrogen fixation. Recent advances in Lotus resource are remarkable. More than 400 markers are mapped in 6 linkage groups. Nearly 40,000 EST clones are available from young seedlings, pods, nodules and roots. Genome sequence project has been started using TAG libraries. Whole genome sequence of Lotus symbiont Mesorhizobium loti has been already finished. Expression profiling by cDNA array, generation of molecular markers and cloning of mutant genes using genome sequence data, analysis of disruption series of Mesorhizobium loti etc. make molecular genetics of lotus symbiosis real.

Journal of plant research