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Fwd: Re: HYB: ?heredity of orange question(s)


While there are orange cartenoid pigments, they are unable to achieve
concentration needed in iris to produce orange colour. The orange
pigment is beta-carotene, which is the most frequent cartenoid in
yellow iris.

 The concentrations of plastids, the main holders of caternoids in
cells, are much lower in iris then other flowers such as pansies. I
have done epidermal peals of these and checked under microscope.
Coverage of pansy plastids can be close to 100% as seen in an epidermal
peel. As seen through entire cell. In Iris this coverage can reach a
high of about 30%, estimation.  This is also why we will not be able to
get a red lycopene iris. We just cant pack enough lycopene into the
iris plastids to produce the intensity of pigment  that would produce
tomato red. (actually tomatoes have a certain percentage of carotene
and the only tomato cultivar without carotene is pink) The highest
concentration of lycopene in flowers  is the red corollas of daffodils.
not sure of what the carotene content of these are.

You can have yellow iris with tangerine red beards. This is a yellow
pigment even though the production from lycopene to carotene is
blocked. This yellow is a recessive, unlike the normal yellow which is
a dominant. Crossing an orange with a white with lycopene beards
produce some of these yellows with lycopene beards.  Thus I call this
yellow the alternative yellow.

When I look at an epidermal peel of an orange, I  see pigment in
cytoplasm as well as in plastids, unlike what I see in pinks and
yellows.

An analysis of pink, orange and yellows with tangerine beard gives
consistent genetic results, showing alternative yellow to be a
recessive and orange to be a combination of this alternative yellow and
pink from carotene.

In addition, beta and alpha carotene are highly soluble in alcohol,
whereas lycopene is minimally soluble in alcohol. If you take a petal
of an orange iris and boil it in alcohol, you are left with a pink
petal. I have posted photos of this in iris-photos some time ago.I have done several pigment extractions with orange iris. First extracting with alcohol, followed by extraction with white lamp oit. In every case I got two pigments. Yellow pigment in alcohol and pink in the residue extracted in oil. Also complete extraction in oil. This oil extract was mixed with alcohol and shaken, then left to separate out. This results in two layers, the yellow pigment moves to alcohol layer and the oil layer , which is pink.

All the evidence is consistent and pointing in same direction. Two pigments, a yellow and lycopene make up the orange colour in orange iris

Granted, there is varying degrees  of orange, and many cultivars have
tonal variations. The catrenoid pigments, both beta-carotene and lycone
 can have various  degrees of intensity and coverage of petals as also
ssen in arious degrees and intensity of anthocyanin, In combination
they can give many shadings of apricot and peach as mixed covering such
as some of the orange indicated.

There are orange amoena iris, but they are uncommon.  As are pink
amoena iris.

The idea that there is an "Orange " pigment in iris is based on the
idea that in some flowers and fruit, beta-carotene can be so
concentrated that we get near true orange colour., such as in oranges.
There is no scientific support of this concept.  If we were able to get
 this sort of concentration of beta-carotene, then we would have have
orange coloured iris without lycopene. No such animal exists. All
orange iris have lycopene.And the presence of lycopene means that the
"normal" production of yellow  beta-carotene has been blocked.

Chuck Chapman

Date: Sun, 04 Jan 2009 07:20:13 -0500
From: Linda Mann <lmann@lock-net.com>
Subject: [iris] Re: HYB: ?heredity of orange question(s)

So, Chuck, Paul, are there three full recessives that can combine to
give various shades of orange (tangerine factor (pink) carotene
pigment,
partially changed tangerine carotene yellow pigment, and a separate,
unchanged (partially changed?) tangerine carotenoid orange pigment)?

Resulting in a hierarchy of colors (sort of like the plicata locus
patterns?)?

Or does each color represent <one> set of identical recessive genes?

If all of these colors are derived from carotene, via some kind suite
of
screwy partial conversions, I guess I don't know how to estimate the
probability of getting orange seedlings from this cross.  Intuition
says
there could be some, but I think I don't have enough information to do
a
punnett square.

I knew the tangerine part was recessive but wasn't sure about the
yellow
part.  & didn't realize there was known to be a separate orange pigment.

I am definitely beyond the limits of what I can figure out... but it
isn't stopping me from trying.

<The apricot  and peach are slightly different genetically.>

- --
Linda Mann east Tennessee USA zone 7/8
East Tennessee Iris Society <http://www.DiscoverET.org/etis>
Region 7, Kentucky-Tennessee <http://www.aisregion7.org>
American Iris Society web site <http://www.irises.org>
talk archives: <http://www.hort.net/lists/iris-talk/>
photos archives: <http://www.hort.net/lists/iris-photos/>
online R&I <http://www.irisregister.com>

------------------------------

Date: Sun, 04 Jan 2009 07:20:48 -0500
From: Linda Mann <lmann@lock-net.com>
Subject: [iris] Re: HYB: ?orange patterns

Betty - that's not what I meant.  I was checking to make sure those
kinds of patterns don't come from the <dosage> of orange genes.   They
come from "pattern" genetics operating on presence or absence of orange
pigments.

<For clarity . . . .there are no orange amoenas, orange with ringed
falls, etc...??? They are not simply difficult, but impossible??

<<(no dosage effects that result in?
patterns other than self - i.e., orange or not orange?)?>.
Betty? W>

- --
Linda Mann east Tennessee USA zone 7/8
East Tennessee Iris Society <http://www.DiscoverET.org/etis>
Region 7, Kentucky-Tennessee <http://www.aisregion7.org>
American Iris Society web site <http://www.irises.org>
talk archives: <http://www.hort.net/lists/iris-talk/>
photos archives: <http://www.hort.net/lists/iris-photos/>
online R&I <http://www.irisregister.com>

------------------------------

Date: Sun, 4 Jan 2009 08:38:10 -0500 (GMT-05:00)
From: Paul Archer <pharcher@mindspring.com>
Subject: Re: [iris] Re: HYB: ?heredity of orange question(s)

Lycopene is recessive to orange and orange (as well as pink) is
recessive to yellow.  Pigment pathway is lycopene converted to orange
then converted to yellow.  The issue that is really in play (in theory)
is the tetraploid factor.  All can be present is various dosages and
have intensifiers and distribution factors.

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