Re: HYB: Seedling Color Characteristics

Sharlyn writes

:>He had a beautiful, golden
:>yellow TB that he produced by crossing CHIEF HEMATITE x WHITE LIGHTNING.
:>My question is how could he end up with a dark yellow by crossing a dark
:>red by a very white iris?  Do seedlings take after their parents in color
:>in most cases or will you get who knows what?  He had a picture of this
:>beautiful TB.  He also had a very white TB with a slight lavender tint that
:>he got by crossing CHIEF HEMATITE with another color, I think it was a
:>purple.  So there you have a red crossed with a purple and you get a white!
:> Please, explain this.  We were under the impression that like produces
:>something like.  It seems this is not dependably so?

I would _expect_ the seedlings from this cross to be mostly yellow selfs.

Here's how it works:

First, understand that the yellow pigments are inherited separately from
the purple ones. When purple and yellow are blended together in the same
flower, the result is red or brown. So you can think of CHIEF HEMATITE as a
purple self plus a yellow self.

Although it is common for white to be recessive to purple in many flowers,
the situation in TB irises is a little different. In the early days, whites
were indeed recessive. But a _dominant_ gene for inhibiting purple pigment
was introduced into garden irises early in this century. These dominant
whites are much purer (no purple undertones, clean hafts), and so were
highly favored. The result is that in TBs nowadays, a flower without any
purple pigment showing (whether white, yellow, pink, or orange) is likely
to have this inhibitor gene. This gene affects only the purple pigments; it
has no effect on the yellow pigments.

Because of this dominant inhibitor, you'd expect most WHITE LIGHTNING
seedlings to show no purple: they might be white or yellow depending on
what genes for yellow they may get from the other parent. (There are
several different genes that control the yellow pigments, but a good
approximation is that yellow is dominant over non-yellow.) Since CHIEF
HEMATITE has yellow genes (that's why it's red and not purple), the
seedlings get their yellow from mommy and their lack of purple from daddy.

I'm a little skeptical of the other case. White (the old recessive white
gene) can crop up when crossing two irises that have purple color, but it
is not too common. Perhaps the other parent was something else? White? pink?

In general, "like begets like" is not something you can count on with
today's TB irises, which have lots of different genes from lots of
different places. The rule works with crossing two recessives, of course
(such as two plicatas), but otherwise all bets are off. You need to
actually know (or make an educated guess) about which genes are
present--and understand how different colors interact--in order to predict
what the seedlings might look like.

Happy irising, Tom


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Tom Tadfor Little                       telp@Rt66.com
Iris-L list owner  *  USDA zone 5/6  *  AIS region 23
Santa Fe, New Mexico (USA)
Telperion Productions      http://www.rt66.com/~telp/
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Iris-L Web Site  http://www.rt66.com/~telp/garden.htm
Other Mailing lists | Author Index | Date Index | Subject Index | Thread Index