Ectopic GUS expression in pollen

[Leonard N. Bloksberg]

In Article <9406011921.AA22224 at mendel.Berkeley.EDU> "williams at MENDEL.BERKELEY.EDU" says:
> Re: Thoma et al. Plant Physiology 105:35-45 (1994) and Uknes et al. Plant
> Cell 5: 159-169.
> 
>         In the first paper the authors describe  a lipid transfer protein
> promoter/GUS fusions in transgenic Arabidopsis. GUS activity appears in the
> pollen but the LTP mRNA does not. In the second paper a similar result was
> found with the PR-1a promoter in tobacco. There the authors also tested a
> second reporter gene and found no activity in tobacco, suggesting that the
> ectopic expression was caused by the GUS coding sequences. 
> 
> I wonder how prevelant ectopic GUS expression in pollen really is? I assume
> the following to be true:
>         *there is no GUS activity in pollen of untransformed plants
>         *there is no GUS activity in pollen of plants transformed with
> pBI101 
>                 (poly-linker fused to GUS with nos 3')
>         *most constructs introduced into plants do not promote GUS
> expression in
>                 pollen
>         
>   I would appreciate hearing from anyone who has detected GUS expression in
> pollen and whether they looked for the endogenous gene in pollen by in situ
> hybridization. Also, has anyone looked into whether the GUS gene effect is
> transcriptional or post-transcriptional? I guess I'm confused because
> ectopic expression in pollen is not found in all transgenics (I assume),
> and most of the reports of pollen specific expression are backed up by in
> situ or northern data. Love to hear from any interested parties!
> 
> Mary Williams (Sussex lab)
> 
> 
There was an old paper that tested about 40 plant species for native GUS 
activity and found only 7 species with no natural GUS activity.  Tobacco 
was definately one of the 7 that do not express GUS.  I seem to recal that
Arabidopsis was amoung the 33 that do, but I have not looked at the paper
in about 2 years.  I'll try to post the reference later.  It's filed at home.
Maybe someone can beat me to it.
.
Leonard N. Bloksberg
bloksber at pilot.msu.edu
.
.