Symbiosis

Warwick Silvester w.silvester at WAIKATO.AC.NZ
Wed Sep 9 16:47:11 EST 1998


I was very interested in the suggestions from Dave Williams about
alternative legumes to use.  The question I have, though, is how do you
obtain the appropriate symbiotic bacteria?  For garden crops, you can buy
them in the garden store - that makes things quite simple for the
experiment that was originally proposed in this group.

Carl S. Pike                             (717) 291-3958
Department of Biology                    FAX (717) 399-4548
Franklin and Marshall College            Internet  C_PIKE at ACAD.FANDM.EDU
P.O. Box 3003
Lancaster, PA  17604-3003  USA


An alternative and extension to the legume Rhizobium theme is to  look at
mycorrhizal responses. At the simplest level sow a variety of seeds on
sterilised and unsterilised soil. The results for some species  eg onion
are spetacular, comparing onion  an oblgate mycorrizal plant with a grass
which has a lower requirement  can be very illuminating..
 This experiment  is compromised by nutrient release from sterilised soil
and better students will pick that the experiment is not properly
controlled. Add to this  by using only sterilised soil and innoculate with
chopped onion roots or a soil innoculum  from healthy pasture or garden.
This works extremely well with clover and can be further expanded to look
at the  so called tripartite symbiosis of  mycorrhiza and Rhizobium. Sow
clover seed into sterilised sand and then  transplant with simple dipping
into chopped onion roots for m innoculum and into crushed clover nodules or
Rhizobium for nodules.This gives a --,-+,+- ,++  scenario and is great for
looking at interactions synergy etc
Other useful symbiosis labs are  structural eg  ecto mycorrhizal roots of
pine or beech are very interesting. The cyanbacterial symbioses of lichens,
liverworts (Anthoceros), Azolla, Cycads, Gunnera provide a wonderful series
of complexity  and a fascinating gradient in heterocyst frequency.
Good luck

Warwick Silvester                      Ph. +64-7-838 4613  and voicemail
Dept of Biological Sciences          Fax +64-7-838 4324
University of Waikato                  Email w.silvester at waikato.ac.nz
Hamilton, New Zealand





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