Alnus Rubra and
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Biology 585 Scanning Electron Microscope Professor: Dr. Darlene Southworth Southern Oregon University |
Obtaining quality micrographs suitable for the purposes of imaging Frankia alni structures within the Alnus rubra root nodules was not overly difficult. It is easy to imagine that while the tissues of interest were living, there were many more visicles inside each cell wall. I did not find any other works that contained images of the subject species. Consultation with Southern Oregon University's Drs. Southworth and Roden confirmed the Frankia presence. Kaufman (p. 211) includes a micrograph of Medicago lupulina in which "the interior of the cell is filled with saclike structures containing the bacteria." I've contacted Frank Dazzo, the biologist responsible for SEM micrograph, and await his professional opinion. This project could be improved with the addition of a control which included micrographs of Alnus rubra roots which were not part of the nodules. An additional project enhancement would be to use the Energy Dispersive X-Ray Analysis feature of the SEM to search for the presence of nitrogen in the vesicles. |
 Figure 8. Red Alder (Alnus rubra) and Black Cottonwood (Populus trichocarpa) thriving together on the Upper Sacramento River. The Cottonwood may benefit from the nitrogen-fixing bacteria living in the Alder roots. |
web page authored by Bob Musgrove