Fine Structure and Spatial Arrangement of Frankia Vesicles in the Root Nodules of Some Actinorhizal Plants Growing in Japan

Abstract

The fine structure and spatial arrangement of Frankia vesicles in the root nodules of Alnus hirsuta, Myrica rubra, Elaeagnus pungens, and Coriaria japonica growing naturally in Japan were compared by electron micrography.
The shape and spatial arrangement of the vesicles in the nodules varied with the species. The vesicles of A. hirsuta and E. pungens were spherical and internally compartmentalized into multiple small segments by septa, and those in M. rubra were ellipsoidal and internally septate. Mesosomes which appeared to be connected to septa were often observed in the vesicles of A. hirsuta and M. rubra. However, clear mesosomes were not observed in the vesicles of E. pungens. The vesicles of C. japonica were club-shaped and arranged peripherally around the central vacuole, and unseparated by septa. Clear lamella mesosomes were observed in the hyphae and appeared to be associated with an electron-translucent nucleoid region.