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Ectopic GUS expression in pollen

Wed Jun 1 14:20:42 EST 1994

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
                (poly-linker fused to GUS with nos 3')
        *most constructs introduced into plants do not promote GUS
expression in
  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)

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