Q: inducible promoters for plants

[Curt Ashendel]

On Mon, 03 Feb 1997 08:09:33 +0100, 
Dr. K. Eimert  <eimert at geisenheim.fa.fh-wiesbaden.de> wrote:

>I am in need of an inducible promoter for plant transformation. It is
>important that this promoter would not "leak" if not induced, e.g., the
>hs-promoter would not work for us. 

We are just starting a project with this, and have chosen to start 
with the tet-derepression system from Christine Gatz, Univ. Bielefeld.
See Meths. Cell Biol. 50:411-424, 1995. I can't report on its 
leakiness, but she claims 500-fold induction

My experience with inducible systems in is mammalian cells, where 
the tet repressible system seems to be king in terms of tight 
regulation. In general with inducible systems, the amount of basal 
expression is related to the amount of induced expression. Zero basal 
expression is essentially impossible. However, the fold-induction 
varies with the systems and the specific stable line that is produced. 
Most of the time, for stably transfected cells, 100-fold induction at 
the mRNA level is very good, and much above 200-fold is rare. If you 
need a low basal level, select a clone that has the level you desire. 
It sounds a bit stange, but it really is a relative thing and 
completely up to the investigator (and the relative toxicity of the 
gene product to the cell). 

Curt Ashendel
Purdue University, West Lafayette, IN
ashendel at purdue.edu