Re: Re: HYB: spots (was another terminology question)
iris@hort.net
  • Subject: Re: Re: HYB: spots (was another terminology question)
  • From: &* W* <i*@telp.com>
  • Date: Tue, 26 Feb 2013 14:41:17 -0700
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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