[edit] Botanical use
Since
chromosome segregation is driven by microtubules, colchicine is also used for inducing
polyploidy in plant cells during
cellular division by inhibiting
chromosome segregation during
meiosis; half the resulting
gametes therefore contain no chromosomes, while the other half contain double the usual number of chromosomes (
i.e.,
diploid instead of
haploid as gametes usually are), and lead to embryos with double the usual number of chromosomes (
i.e. tetraploid instead of diploid). While this would be fatal in animal cells, in plant cells it is not only usually well tolerated, but in fact frequently results in plants which are larger, hardier, faster growing, and in general more desirable than the normally diploid parents; for this reason, this type of genetic manipulation is frequently used in breeding plants commercially. In addition, when such a tetraploid plant is crossed with a diploid plant, the
triploid offspring will be sterile, which may be commercially useful in itself by requiring growers to buy seed from the supplier, but also can often be induced to create a "seedless" fruit if pollinated (usually the triploid will also not produce pollen, therefore a diploid parent is needed to provide the pollen). This is the method used to create seedless
watermelons, for instance. On the other hand, colchicine's ability to induce polyploidy can be exploited to render infertile hybrids fertile, as is done when breeding
triticale from
wheat and
rye. Wheat is typically tetraploid and rye diploid, with the triploid hybrid infertile. Treatment with colchicine of triploid triticale gives fertile
hexaploid triticale.
When used to induce
polyploidy in plants, colchicine is usually applied to the plant as a cream. It has to be applied to a growth point of the plant, such as an apical tip, shoot or sucker. Seeds can be presoaked in a colchicine solution before planting. As colchicine
could be used