Re: chromosomes
- To: hosta-open@mallorn.com
- Subject: Re: chromosomes
- From: h*@open.org
- Date: Sat, 18 Nov 2000 21:48:10 -0800 (PST)
Ben:
>Of course it is possible to look at the chromosomes and count them,
>after coloring with Feulgen reagens. I have done that in houseleeks
>BUT it is very laborious. Only cells that happen to be in mitose can
>be counted that means a lot of searching through cut or crushed
>tissue.
It is obvious that you are NOT a botanist! Granted, it does take some
time to do a proper chromosome count, but it is NOT difficult to do.
I don't know about over there in Holland, but here in the USA we teach
high schools kids how to do chromosome counts! All you have to do Ben
is take some actively growing root tips, do the necessary maceration
and then stain it. You can do a quick count in as little as 30
minutes! If you go to your university library you will find books on
plant microtechniques that explains how to do it in detail.
Granted, flow cytometry is a very quick means for getting a good idea
of what a plants ploidy level is, but if you want to be absolutely
accurate you really need to do a chromosome count.
>If ventricosa (41pg) crosses with another tetraploid plant like some
>Fortuneis (51) the tetraploid offspring will have 1/2 (41 + 51) =
>46pg. If ventricosa crosses with a diploid plant let say sieboldiana
>(25pg) the triploid ofspring will have 1/2 (41+25)=33 pg So this
>excludes ventricosa as a parent for S&S (39)
Ben, this is pure nonsense to say such-and-such is or isn't a parent
of such-and-such a hosta based on the amount of DNA in the nucellus.
It many be additional evidence, but you really need a lot of other
morphological, anatomical and karyotype data before you can make any
claims for parentage.
Joe Halinar
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