I am surprised at your comments since I am unaware of a double
homozygous recessive genotype in the carotenoid pathway producing any
color other than that of the first loci being blocked. I assume `t'
precedes `ya' in your pathway and in which case the (tttt, ya ya ya
ya) genotype would have a pink phenotype or lycopene would be the
dominant color.
If you are finding lycopene in an orange flower it is because not all
of the lycopene is converted into beta-carotene which, when
beta-carotene is the predominant carotenoid, makes the flower orange.
Recall, lycopene is the substrate for beta-carotene. Thus, there will
always be lycopene in orange and yellow flowers at trace levels.
Also, if the orange genotype is (tttt, yayayaya) then what is the pink
genotype? You say Girl Pixie doesn't have any ya genes, isn't that the
same as saying the ya locus is homozygous recessive? As presented,
your genetic explanation does not explain the difference between pink
and orange.
The best evidence I have right now that orange has its own gene is the
simple fact that orange flowers exist. Also, Aitken and other authors
in the AIS literature have stated orange is a recessive trait. Since,
their claim is consistent with the carotenoid pathway as it is
understood today, I agree with them.
On another note, the AIS chose the symbol `o' for the orange break in
1961. I suggest you not make any changes to the nomenclature by adding
ya until you can show how it relates to the pathway. There are already
too many half baked ideas in iris genetics.
--- In iris-photos@yahoogroups.com, "irischap" <irischapman@...> wrote:
>
> This is indeed a nice photo of an snow resistant flower.
>
> I do differ with you re interpreting the genetics of this. I view
> Infanta as having four sets of the tangerine gene that is tttt.
> As well as with all oranges it also has four sets of a recessive
> yellow gene that seems to only be associated with the orange iris.
> (research still pending) that I will call , for the time being
> "alternate yellow", and label it ya, so that Infanta is tttt yayayaya.
>
> To check this out further I would suggest that you either grind up an
> Infanta petal in methyl alcohol and filter it. As lycopene is only
> partially soluble in alcohol, the residue would show the typical
> lycopene pink colour. An alternative would be to boil an intact petal
> of Infanta in methyl alcohol, this will reveal the underlying lycopene.
>
> Thus Infanta X a pink, will produce all flowers with lycopene. If
> Girl Pixie doesn't have any ya genes then all the seedlings will be
> pink. Of course there are the anthocyanin genes in Infanta which,
> depending on the mix of anthocyanin genes in Girl Pixie, will show in
> various ways.
>
> Thus when we have a cross of two orange iris, we have a cross of tttt
> yayayaya X tttt yayayaya and thus all the offspring will be tttt
> yayayaya and thus orange.
>
> I have not seen any evidence that would convince me that there is a
> seperate gene for orange, or that it is anything other then a mix of
> yellow and lycopene.
>
> Please feel free to send any information you have (evidence, not
> theory) that there is a gene for orange, that can not be explained by
> what I have outlined above.
>
> Check the colour of the rest of the seedlings in this cross.
>
> Chuck Chapman
>
> --- In iris-photos@yahoogroups.com, "Dan Meckenstock" <dmeck@> wrote:
> >
> > This special SDB ice pink is the product of years of breeding and,
> of course, divine intervention. Last night while I was sleeping the
> skies opened up and miraculously turned this early bird into an ice
> pink. Note the exceptional cold tolerance of this seedling. If this is
> not proof intelligent design then I do not know what is. I think I
> will release this little miracle for use in Barrow Alaska--call it
> PINK ICE CREAM.
> >
> >
> >
> > On a more serious note, this seedling is an F1 derived from the
> cross (Infanta x Girl Pixie). Where Infanta is a light orange glaciata
> and Girl Pixie is pink. We know from this F1 that the genotype of
> Infanta is heterozygous TTtt, and homozygous oooo where T promotes the
> conversion of lycopene into beta-carotene and 'o' blocks the
> conversion of orange beta-carotene into yellow zeaxanthin. It is quite
> possible that Infanta's TTtt genotype reduces its concentration of
> beta-carotene thus producing its light orange appearance.
> >
> >
> >
> > Girl Pixie is pink and carries the tttt genotype.
> >
>
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