Bacteria that do associate with plants include the actinobacteria Frankia, which form symbiotic root nodules in actinorhizal plants, and several cyanobacteria (Nostoc) associated with aquatic ferns, Cycas and Gunneras.
Rhizobia |
Rhizobia—these are the species that associate with legumes, plants of the Fabaceae family.
Frankia is a genus of nitrogen fixing, filamentous bacteria that live in symbiosis with actinorhizal plants, similar to the Rhizobia bacteria that are found in the root nodules of legumes in the Fabaceae family.
Root nodules that occur on non-legume genera like Parasponia in association with Rhizobium bacteria, and those that arise from symbiotic interactions with Actinobacteria Frankia in some plant genera such as Alnus, vary significantly from those formed in the legume-rhizobia symbiosis.