An Electron Microscopic Observations on the Bacteroid Structure of Root Nodules in Winged Bean(Psophocarpus tetragonolobus)

The ultrastructure of root nodules of winged bean has been examined by trans mission electron microscopy.During development winged bean root nodules undergo a series of ultrastructural changes including the release of bacteria from the infection thread, rhizobia(Rhizobium sp.)infection that released into the host cells gradually turned to N-fixation bacteroids.The bacteroids are enclosed by envelope membranes(enclosing membrane or bacteroid perimembrane).In any asynchronous there are four different cells structural forms in root nodules:(A)immature bacteroids,(B)mature bacteroids,(C)senescent bacteroids and(D)infection thread rhizobia.During the individual development of a bacterial cells, a serie, of changes in morphological character have been observed.These changes are described in detail and the significance of the structural changes and their relationship to the development of root nodules are discussed.