View Single Post
  #3   Report Post  
Old 17-10-2003, 12:23 PM
Craig
 
Posts: n/a
Default Role of RNA Silencing in Plants

If this is a school or uni question you should have access to bids/web
of science/ science direct and be able to find the current articles if
not try scirus.

if memory serves the current hypothesis is that plants are able to take
advantage of the fact that a lot of plant viral pathogens have a double
stranded RNA genome.
The double stranded RNA is cut up in to ~23bp bits by a DICER (?)
enzyme, these bits are used to prime binding of another RNAse so and
single stranded RNA is also rendered untranslatable.

This silencing ability is able to spread from the site of initial
activation thus protecting the new plant growth (i don't remember if it
spreads to existing tissue).

look up: PTGS - post transcription gene silencing, siRNA short
interfering RNAs

i've just found a useful article - Waterhouse et al TRENDS in plant
science vol 6 no 7 2001 p297


How does the knowledge of RNA Silencing in plants help us in
develpoing new viral resistant varities ?


depends on the plant and it's uses. in theory you could have a varetiy
of conserved viral sequences constitutively expressed as hair pins (will
make a double stranded RNA on their own) so the virus can't get a 'foot
hold' and do damage with infection. however this would cost the plant.
If you happen to be a faceless multinational who wants to generate some
transgenic monoclonal crop plant then some version of this would
probably be what your looking for as it would be easy to make (depend on
transformation efficiency of the plant of course). there would be more
elegant methods - inducible systems linked to a transcriptional
activator (gal4 ?) and kicking out a variety of hairpins then shutting
down when not in use. although being a thing of beauty such system would
probably never get funding because it would take at least twice as long
to make then you should do lengthy trails as any transgene could affect
the metabolic profile of the plant in an unpredictable way.
grrr.
ops. time for me to have a little sit down.

craig