- Subject: Re: [IGSROBIN] Hybridizing
- From: "Roth, Barry" <BRoth@BROBECK.COM>
- Date: Tue, 23 Oct 2001 15:39:23 -0700
Another approach is to artificially double the chromosome load of a diploid.
This can be done by applying certain chemicals (colchicine is one) to seeds
or to growing tip tissues (meristems) of the diploid variety. I believe
this has been done with P. x hortorum to bring certain characters into the
tetraploid range (the "dark dwarf" condition is one).
I experimented with this some years ago, without much success, although I
had some fun in the process. It seems that the dose of chemical necessary
to cause doubling of chromosomes is very close to a lethal dose. (No
surprise -- it's really messing with the biochemical framework of the plant
itself.) Another limitation is that, unless the parent plant of the seeds
you are treating is from a very inbred line -- that is, with most of its
characters in the homozygous state -- the seeds may not carry the very
characters you are hoping to transmit. For example, I believe the "dark
dwarf" allele is dominant and that very many, if not most dark dwarfs in the
trade are heterozygous for full-size (non-dwarf) growth habit.
The chemicals are hazardous materials and must be handled with appropriate
On Monday, October 22, 2001 11:03 PM, Cynthia S. Lohry
>While hybridizing interests me, I have not done much with it. From
>asking questions of others, my understanding is that in a labratory,
>under very controlled circumstances, you can cross a tetraploid with a
>diploid. But, that once you have that offspring, it is sterile, and
>you cannot cross it with anything else to carry on the line.
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