Need references on plant growth factors produced by microbes.

[Charles Soto]

I am looking for biochemical references to plant growth factor production
by microbes (pref. protists).  I have seen it mentioned in many texts
about rhizosphere and soil ecology, but have never seen a biochemical
mechanism.

If you can point me to a text or article, please email me.

Regards,
Charles

Charles Soto - hamlet at mail.utexas.edu

The Unrestrained Use of Excessive Force