Re: What is Aneuploidy?

**&* C* <T*@mobot.org>**

Dear Ted:

	In our breeding studies here at the Missouri Botanical Gardens
we have found that intersectional crosses are rare, usually impossible
so the chromosome counts are not the only determining factor because
several sections share 2n=30. Also aneuploidy appears to be in evidence
in sect. Porphyrochitonium which has chromosome levels of 28,29,30, 31
for example and these numbers can arrive by unequal crossing and through
the production of triploids which can cross because they have a full
complement of chromosomes.  Really we ought to get Dick Sheffer to
expound on this.  That is his area of expertice.

Tom 

-----Original Message-----
From: aroid-l-bounces@gizmoworks.com
[aroid-l-bounces@gizmoworks.com] On Behalf Of brian lee
Sent: Tuesday, January 08, 2008 3:48 AM
To: Discussion of aroids
Subject: Re: [Aroid-l] What is Aneuploidy?

Dear Ted,

Aloha.  I think the best thing for you to do is to
look at Botany Online...it will help you on some of
the questions you pose.

In a nutshell, aneuploidy messes things up.  In
humans, tumors and Down's Syndrome are examples.  In
plants, death or deviant growth patterns are observed.

Aloha,

Leland

--- ted.held@us.henkel.com wrote:

> Dear List,
> 
> I have managed to finish the latest Aroideana. It's
> probably a good thing 
> for me this comes out only once a year as it seems
> like it takes me a year 
> to read and digest what's in one. Being a lay
> person, some of the articles 
> can be heavy-going. The one entitled "The Chromosome
> Numbers of the Aroid 
> Genera", by Dr. Bogner, is a case in point. I am
> trying to sort out what 
> the apparent promiscuity of aroids with regard to
> chromosome numbers might 
> mean. Here are some questions?
> 
> 1. Do all the plants within a given species have the
> same basic "X" number 
> of chromosomes? Does this mean a species within the
> genus Landoltia, for 
> example, might have a normal 2n chromosome count of
> 40 with haploid (2n = 
> 20), diploid (2n = 80), etc., variations, but not 2n
> = 46? So if you have 
> two plants, one with 2n = 40 and another with 2n =
> 46, do you know you 
> have two different species?
> 2. Can plants with different chromosome counts be
> cross fertile? Can a 2n 
> = 40 plant produce viable seed with its own diploid?
> How about with a 
> plant in the same genus with a chromosome count of
> 2n = 46?
> 3. What happens when a plant messes up and undergoes
> aneuploidy. 
> Aneuploidy is defined in the text as when some type
> of evolution takes 
> place where the offspring end up with a few extra
> chromosomes here and 
> there. Doesn't this mess up the plant? If not, why
> not?
> 4. Similarly, there is a term called dysploidy where
> a few chromosomes 
> don't make it into the new plants, or where old
> chromosomes get pieces 
> chewed off, somehow. Don't plants need at least a
> portion of the 
> information contained in the chromosome arms?
> Doesn't this mess up the 
> plant? If not, why not?
> 5. Can a plant that has experienced aneuploidy or
> dysploidy produce viable 
> seed with a normal-count plant? Or does the plant
> have to reproduce 
> vegetatively for a while until there is another
> receptive brother or 
> sister with whom to mate?
> 6. How much messing around with chromosome numbers
> does it take before the 
> morphological differences are large enough to
> produce a new genus?
> 
> Please take pity on me. When I went to school all
> this was very new. Come 
> to think of it Darwin was new stuff back in those
> days.
> 
> Ted.
> > _______________________________________________
> Aroid-L mailing list
> Aroid-L@www.gizmoworks.com
> http://www.gizmoworks.com/mailman/listinfo/aroid-l
> 

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