HYB: more about "recessive" pink

Mary Swann-Young asked a question about a chimera she had in 'Pagan Pink.'  It
may be helpful if I go a little further in answering her question.

First of all, the only thing "recessive" about a normal pink is the conversion
factor ("t" for tangerine) that converts some yellow carotenoid pigments to
Lycopene--a chemical you hear lots about on TV these days.  Lycopene is an
orange-red pigment responsible for part of the color of tomatoes

A pink iris must be several things all at the same time:

1) a yellow--which is a dominant trait that can range from pale ivory to rich
gold depending on how many of the four possible doses it can have are
present--along with several other qualifying factors;

2) a dominant white (usually)--meaning that the normal blue-violet to violet
pigment of irises (violanin, or delphinidin, depending on who is writing) is
converted to a colorless or nearly colorless form during production--there are
a number of exceptions to this--a pink can be a glaciata, or a recessive
white, but the usual case is the first one stated.  The dominant white factor
is usually present only one or two times. Two pinks crossed with each other
usually have a few purplish pink or violet seedlings with tangerine beards in
the batch.  A classic example of where the dominant white is *not* inherited
is found in the Dykes Medal winner 'Mary Randall.'

3) a plant with four doses of a recessive conversion factor which diverts the
synthesis of the normal yellow Carotene over into a similar molecule called
Lycopene which is orange-pink.  Those with only three doses are said by
some--including both Chuck Chapman and myself--to have a rather creamy warm
look to the yellow that sometimes can be recognized in the garden.  Apparently
a little of the carotene is coverted if the plant is "Tttt"--one dose normal,
three doses conversion factor.

Keith Keppel, I believe, has suggested this "t" factor came into modern
tetraploids from *Iris kashmiriana.*  It first showed up in the late twenties
or early thirties, but was not recognized until both Dr. Loomis in Colorado
and David Hall north of Chicago began getting seedlings that looked pink in
the bud.  Hall's first really obvious pinks bloomed in 1942 and created a
sensation.

An example of how the yellow and the pink are related is shown in a cross made
by Tell Muhlestein in Utah.  He had David Hall's yellow, 'Golden Eagle,' which
was from some of the same breeding as Hall's pinks.  Tell crossed this yellow
with a tall, pale pink from Dr. Loomis known at that time as SQ-72, but which
was registered much later by Melba Hamblen for Dr. Loomis as 'Pikes Peak
Pink.'  Among the results were the brilliant salmon-pink 'Pink Formal' and
another seedling Tell named 'Pink Tower.'  Tell never said what the ratio of
yellows to pinks was in the seedlings, but I would not be surprised if there
were more yellows than pinks, and even some blends--on the order of 'Prairie
Sunset.'

A "recessive pink" describes only the recessive character of the conversion
factor "t."  Everything else must usually be in the dominant form.  Please
note I did say there were exceptions.

Neil Mogensen  z 7 western NC mountains

---------------------------------------------------------------------
To sign-off this list, send email to majordomo@hort.net with the
message text UNSUBSCRIBE IRIS
Other Mailing lists | Author Index | Date Index | Subject Index | Thread Index