Function and regulation of the early nodulin gene ENOD2

The symbiosis between (brady)rhizobia and legumes is known to proceed through a series of characteristic stages. The pre-infection stage includes recognition of two symbiotic partners, attachment of bacteria to the plant roots and deformation of root hairs. In the next stage, deformed root hairs are invaded by bacteria which grow and penetrate within a unique plant-derived infection thread. At the same time cell division is initiated in root cortical cells and this elaborates the formation of meristems. Infection threads grow towards these meristems and a nodule structure is formed wherein differentiation of tissue type occurs. From the growing infection thread bacteria are released into some of the newly formed nodule cells. Finally, the cooperation of nodule cells and differentiated bacteroids leads to a nitrogen fixing plant organ.