Re: Re: HYB: spots (was another terminology question)
iris@hort.net
  • Subject: Re: Re: HYB: spots (was another terminology question)
  • From: C* C* <i*@aim.com>
  • Date: Tue, 26 Feb 2013 17:18:33 -0500 (EST)
I'd like the references for four pumilla pairing with 4 TB. that would be interesting.
In this situation I would think that what you would have would be 12 bivalents and 20 univalents. (Unless there really are 4 chromosomes which can pair up). But a 12 +4 univalent and a 8 + 4 univalent would still be unviable. Just too many univalents. Some would be silenced (that is just the way it happens) thus plant would not be able to live. Too many enzymes and proteins missing.
With unmatched chomosomes of close to full sets, as long as there is one of each chromosomes for each set, there can be some viability. There is various ways this can happen. Such as the sets with one less chromosome is often a joining of two other chromosomes. Thus he two in other plant, that have joined, would have coresponding regions, and can line up with the corresponding one. then during cross over , the two can do a disjunctive joining, loose the extra centomere and become a functional , rejoined chromosome. In this case there will be a section of of a chromosome without centromere , which can randomly move into one cell. And as it doesn't have a centromere, it will be lost in meiosis.
You need a full set of chromosomes, and this depends how they are packed in the chromosomes. Some can function as univalents but as long as they are not part of the "silenced" genome, where this happens.
A lot more possibilities, which just don't work. I'm not going to go into them right now.
So after all this consideration, it is why I still think a number of fertile are large SDB, that is 12/12/8/8. A count of some of these fertile IB would be interesting. I have gotten a few tall SDBand have seen several of them registered as IB, so I know that there are some out there. But that doesn't mean all of the fertile IB are of this amphidiploid type.
Some of these fertile IB are fertile in IB X IB crosses , Which seems as if it would only be possible if they were amphidiploid. 

Chuck Chapman

-----Original Message-----
From: Tom Waters <irises@telp.com>
To: iris <iris@hort.net>
Sent: Tue, Feb 26, 2013 4:47 pm
Subject: Re: [iris] Re: HYB: spots (was another terminology question)
There have been observations of four pumila chromosomes pairing with four TB chromosomes in IBs and (I think) 36-chromosome MDBs. These unbalanced 
tetraploids are not completely infertile by any means, and relatively
fertile ones seem to be becoming more common with time, which I have no
explanation for. Some used to give a "rule of thumb" that if the bivalents outnumber the univalents, some fertility can be expected. If you have the pairing of four chromosomes I mentioned, an IB has 12+4=16 bivalents, and 
8+4=12 univalents.
We also see partial fertility in the 1/4 aril arilbreds.
I think the supposition is that unpaired chromosomes do not necessarily
stop the plant from making gametes, and the unpaired ones just end up in the gametes randomly. It's possible to have a viable plant with one of two extra chromosomes (or one or two missing ones); these are aneuploids. So 
the fertile gametes from these unbalanced tetraploids are those that
randomly receive an approximately complete set. The probability of that is 
small, but can be great enough to get some good seeds in some cases.
Tom




Tom Waters


Telperion Oasis ~ www.telp.com/irises


Cuyamungue, New Mexico, USA (zone 6)

----------------------------------------
From: "Bill Chaney" <billchaney@ymail.com>
Sent: Tuesday, February 26, 2013 12:02 PM
To: "iris@hort.net" <iris@hort.net>
Subject: Re: [iris] Re: HYB: spots (was another terminology question)

I don't want to distract the discussion that is ongoing, but I can't
resist
jumping in when Chuck brings up the 12/12/8/8 ploidy because I am trying 
to
understand how some of these IBs are so fertile with TBs and MTBs.
Especially
if the 12/12 side comes from aphylla background.  Would anyone care to
comment
on that or point me to a good source of information?

Thanks
Bill
________________________________
From: Chuck Chapman
To: iris@hort.net
Sent: Tuesday, February 26, 2013 8:06 AM
Subject: Re:
[iris] Re: HYB: spots (was another terminology question)

Amphidiploid is
12/12/8/8  these are SDB

There can't be cross overs between any chromosome
from 8 set and 12 set, as they never pair up in meiosis. Crossovers only 
occur
in paired chromosomes. No pairs = no crossovers. Like, never ever. If they 
ever did, their would be unbalanced chromosomes, and  it wouldn't be
viable.
that is  the  meiotic cell would die, or any zygote formed would die.

IB is
12/12/12/8 So can be pumilla spot, on one of the chromosomes from the "8 
chromosomes"  set.

RE; Chocolate Truffle.  TB X pumilla = SDB  No exceptions.
And for kickers, ruffles" a recessive trait that just isn't present in
pumilla
species. So where are genes for ruffles coming from?  Hell's Fire is a
reddish
black, with multiple dosages of Ae (check pedigree) Thus all seedlings 
will
be purple in a cross with a yellow. So are you still believing this
pedigree?
Chuck Chapman

-----Original Message-----
From: Linda Mann

To: iris
Sent: Tue, Feb 26, 2013 10:41 am
Subject: Re: [iris] Re: HYB: spots (was another terminology question)
Amphidiploid version could.

On 2/26/2013 9:09 AM, Chuck Chapman wrote:

The

pumilla spot is only on the "8 chromosome" set. So can't show up
in TB,
Agree, spots are interesting.

TB e-register from pumila, first generation.
There is another one
registered as a TB, but class is probably a typo - it's
IB height.
Others SDB breeding? fertile IBs? cross overs?

CHOCOLATE TRUFFLE
 (Mark Grumbine, R. 2006) Sdlg. MG04-407-7. TB, 29"
(74 cm), EM     S. light
yellow-brown; F. dark mahogany brown, light
yellow area around beards and
shoulders; beards orange; ruffled. Hells
Fire X I. pumila, yellow

eagerly
waiting to see the '39 checklist (Mike, any more TBs registered
from that era
from pumilas?)

Are there more?  What about the pumila spot work that Blyth
was doing,
trying to bring spot 'up' to TB size? Zing Me.
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