DOE JGI Science Highlights: Boosting knowledge of nitrogen-fixing bacteria

No plant is an island; interactions with complex microbial communities both above the ground and below the ground shape the plant’s growth rates and overall health. Understanding these plant-microbe interactions can lead to improvements in plant health and productivity and carbon sequestration, which can be applied toward DOE missions in bioenergy and biogeochemistry.

Dark-field photo of Frankia vesicle clusters (single plant cells filled with the filamentous organism) 

that have broken free from nodules in the plant Coriaria arborea. 

(Image courtesy of David Benson, University of Connecticut)

Often found in the roots of plants in nitrogen-poor soils, Frankia bacteria can supply most, if not all of a plant’s nitrogen needs by fixing atmospheric nitrogen gas. In the December 2011 issue of the Journal of Bacteriology, DOE JGI collaborators David Benson from the University of Connecticut, Katharina Pawloski from Stockholm University in Sweden and Alison Berry from the University of California, Davis discussed the genome sequence of a bacterium from a noncultured clade of Frankia isolated from the Durango root, a noxious weed found in California and Nevada.

“Frankia strains are filamentous, sporulating, aerobic actinobacteria that induce nitrogen-fixing root nodules on about 220 plant species from eight families in three orders,” the team noted in their report, adding that the 5.3-million basepair genome is the smallest sequenced thus far.

The work is related to their 2007 DOE JGI Community Sequencing Program project, which focused on using the genomic data to learn more about the symbiosis and stress responses found in the relationship between plant host and bacteria.