Molecular Genetics of Symbiotic Plant-Microbe Interactions Using a Model Legume, Lotus japonicus

摘要

Legume plants are able to form nitrogen-fixing root nodules by symbiotic interactions with soil bacteria collectively termed Rhizobium. The interactions of legume plants and Rhizobium bacteria initiate from the colonization of rhizobia on legume root hairs, followed by invasion of rhizobia into root epidermis and then cortical cells through infection threads. Concomi-tantly with the bacterial infection process, cell division is induced in the root cortex to form a nodule primordium, which successively develops into a highly organized symbiotic organ, the root nodule. In the nodules, rhizobia are enclosed by a plant-derived symbiosis-specific membrane (the peribacteroid membrane, PBM) and differentiate to bacteroids, and fixation of atmospheric nitrogen takes place.