colchicine

Scott Williamson scwilli2 at unity.ncsu.edu
Tue Mar 8 15:05:49 EST 1994


Subject: colchicine
From: Stephen Canepa, stephen.canepa at cld9.com
Date: Sat,  5 Mar 94 12:51:00 -0600
In article <7.1507.1756.0N5C281A at cld9.com> Stephen Canepa,
stephen.canepa at cld9.com writes:
>       I am trying to help a friend who does not have access to usenet.
>He is trying to do some experiments using colchicine on gourd plants.
>He has purchased a gram of powdered colchicine ($80.00), but there
are
>no instructions on dilution etc.  He knows that it is poisonous and
>plans on using rubber gloves and a respirator.  His plan is to spray
the
>mixture on different stages of seedling growth to create polyploids.
>None of the resultant plants will be used for food.  Can someone
please
>help with instructions on dilution rates, methods of creating solution,
>etc.  Any help will be greatly appreciated.  You can post in the
>conference or email to my address.  Thank you,  Stephen Canepa
>        internet address:  stephen.canepa at nitelog.com
>---
> ! [R2.00o] ! Usenet ! Nitelog BBS ! Monterey CA ! 408-655-1096
    My previous post didn!t work, so I!ll try again.

     Colchicine has been widely used to induce polyploids since 1937, so
there is a vast amount of literature available on its use on many
plants. Any university library will have many references on the
subject, including papers on treating specific crops. A useful paper on
particular techniques is:

Sebastiampillai, A.R., and J.K. Jones. 1976. Improved Techniques for
the Induction and Isolation of Polyploids in the Genus Fragaria.
Euphytica 25: 725-732.

     Your friend!s use of seedlings is fortunate because colchicine
affects the tissues with which it comes into contact (including human
tissue - wear latex gloves). Often the growing point (which is the area
you want to affect in order to isolate polyploids)on mature plants is
buried under other tissues (bud scales, unexpanded leaves, etc.)
which prevents the colchicine from reaching the growing point. In
addition, colchicine can completely arrest root growth,so treating the
growing point directly is better than seedling immersion.
     I have found that the most effective treatment method is to place
a drop of colchicine solution between the cotyledons of the seedling
for a period of 24 hours. The seedling should be placed in a covered
container to maintain high humidity, which will prevent the colchicine
solution from evaporating.
     Different plants have different sensitivitiesto colchicine, so some
experimentation will need to be done to find the right
concentrationthat will affect the plants without killing them. For
treatment using the drop between the cotyledons, a concentration of
2-3% colchicine in waterworked best. Your friend may want to try
treating small groups of plants, treating one group with 0.5%, others
with 1%, 2%, and 3% to get an idea of how his plants react to the
treatments. If larger areas of tissue are treated, lower
concentrations (0.05-1%) should be used to prevent the killing of the
plants.
     It is because such a small area is being treated with the drop
method, that a higher concentration of colchicine can be used.
Because of this higher concentration, it is more likely to affect the
growing point and this increases the chance of securing polyploids.
     Polyploids can be recognized by their appearance. Generally, you
will see  an increase in the size (especially width) and thickness of
the leaves. Cromosome doubling is often used in flower breeding
(especially with orchids) because it results in larger flowers with
broader petals.
     Best of luck to your friend.



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