- Subject: HYB:Colchicine
- From: Bill Shear <firstname.lastname@example.org>
- Date: Sat, 29 Dec 2001 12:02:49 -0500
I saw upon returning from the holidays numerous messages on the list
regarding the use of colchicine to obtain tetraploid plants from diploids.
I'm very concerned about what seems to be a cavalier attitude toward this
deadly poisonous substance--particularly disturbing was the quote from Sam
Norris averring that he "puts colchicine on everything." I am sure that
Norris was exaggerating for effect and that he, as a responsible plant
breeder, uses colchicine with caution and discretion.
Cochicine has been known since antiquity as a deadly poison--as Dennis has
pointed out, even very small amounts, such as might adhere to one's fingers
after careless use, can be very, very harmful, even lethal. So far as I
know, there is no antidote to this poison, but perhaps if we have a member
who is a medical doctor or toxicologist, he/she can fill that gap.
I woud strongly caution anyone who is not intimately familiar with the use
of this substance, or who can get instruction from one who is, to please not
buy it or use it.
With all of the tetraploid bearded irises available today, with all the
genetic material they bear (including genes for variegated foliage), it
seems an uneccessary risk to use this hazardous compound to attempt the
conversion of diploids to tetraploids. Breeders have, in fact, been far
more successful moving genes from diploids to tetraploids by careful
breeding. Colchicine is not a "magic wand" that automatically converts
diploids to tetraploids. Experiences reported by Currier McEwan and others
document a very, very high failure rate with all methods tried. Many, many
plants or seeds must be treated for even a few conversions.
This is undoubtedly due to the deadly consequences for both plant and animal
cells of cochicine's action in halting cell division. Only in the very few
cases in which cell division begins again will the plant survive. And even
in these cases, the conversion to tetraploidy may be only partial, resulting
in a plant that may soon revert to being diploid--colchicine-converted
plants are notoriously unstable.
What I am trying to say here is that working with colchicine is dangerous
and the success rate is low. Even the successes may evaporate after a while
as the unstable chimeras go back to being diploids. Please carefully weigh
the dangers against the potential benefits before buying and using this
I sincerely hope that those of you planning to use colchicine without
previous experience or instruction will reconsider your plan.
Department of Biology
Hampden-Sydney VA 23943
Coleus at http://groups.yahoo.com/group/coleus
Opiliones at http://groups.yahoo.com/group/opiliones
Myriapod at http://groups.yahoo.com/group/myriapod
"A man thinks as well through his legs and arms as his brain. We exaggerate
the importance and exclusiveness of the headquarters. Do you suppose they
were a race of consumptives and dyspeptics who invented Grecian mythology
and poetry? The poet's words are, "You would almost say the body thought!"
I quite say it. I trust we have a good body then." --Henry David Thoreau,
Journals, Dec. 31, 1860.
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