Re: Re: Iris attica (was more questions from the newbie)

Monday, February 09, 2004, 11:12:46 PM, you wrote:

>> Robt R Pries <rpries@s...> wrote:
>> ... the attica clones that have been tested are diploid and would likely be sterile when crossed to tetraploids or amphidiploids.

l> I'm confused ... again.  I could sit down with TWOI and try to muddle 
l> through the genetics chapter for the umpteenth time, but I doubt it 
l> would make any more sense to me now than it did the first couple dozen 
l> times I tried to absorb it.  What I really need is a "Chromosomes for 
l> Dummies" version of the same info.

l> I don't understand why beardless species seem to be able to interbreed 
l> successfully regardless of varying chromosome counts, while beardeds 
l> can not.  Sibtosa works, but attica X pumila doesn't?  I just don't 
l> get it.

l> Can anyone offer an idiot-proof explanation in 500 words or less, 
l> please?  ;-)

l> Laurie
                                                           

Laurie,
don't confuse chromosome count and ploidity. Chromosome is carrier of
information. More chromosome-more information. Sometimes the same
species has different chromosome number, depending on growing
conditions in different areas /of course, succeeded for many ages/.
Crossing two diploid species, or the same species with different
number of chromosomes you will have also diploid, but with one set
of chromosomes from pod parent another from polen. F.egz. crossing
plant with 24chr /most of bearded diploids/ with 36chr. you will have
plant with 30chr. Crossing tetraploid with tetraploid you will have
tetraploid. But crossing diploid which is I.attica with tetraploid
I.pumila you will have triploid steril plant with 24chr.
(16/2+32/2=24) with no creative possibilities in future. But...
citological research in USA found that possibly I.pumila is natural
hybrid of I.attica and I.pseudopumila, but with full chromosome count
of both parents (16+16=32). So achieved tetraploid level. But why not
to try get tetraploid from I.attica and I.pseudopumila in artificial
way with colchicine treatment how it was done with siberians by
Dr.Currier McEwe. Each time chromosome combinations can be different
and it can be interesting work. But I doubt.
Edmundas Kondratas
Kaunas, Lithuania
 k*@delfi.lt




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