Here is the article, reproduced below!!!
I happened to notice that Brad has used (based on the seedlings he posted) Just Witchery as the pod parent, and it has passed on it's great form to its kids, and it explains why his many seedlings crossed with My Beloved as the pollen parent turn out white/pale. The short version: pod parent tends to determine form/growth, pollen parent the color, says Barry Blyth.
It also explains why the seedling that Keppel uses to provide great stems (and is not very remarkable for color), that Brad pointed out on this thread, seems to be used over and over in the pod position (per our database) and results in a wide variety of colors. Thank you again, Laurie, for calling my attention to this.
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From the Oct 2007 AIS Bulletin
Reciprocal crosses are crosses that are reversed. For example, in a
cross where variety A is the pod parent, and variety B is the pollen
parent (A x B), its reciprocal would be (B x A) with variety B as
the pod parent and variety A as the pollen parent. Many people assume
that it makes no difference which variety is chosen to be the pod parent
and which the pollen parent. Insofar as the transmission of chromosomal
genes is concerned, this is certainly true. However, insightful observations
from hybridizer Barry Blyth challenge this paradigm.
Following up on a rumor that Australian hybridizer Barry Blyth was
finding evidence of differences in reciprocal crosses, I went in search of
more information. Sure enough, Blyth is finding subtle differences in
all reciprocal crosses where he has sufficient progeny to note trends. He
observes that "even when they are close in pattern or form, there is always
something subtle that can be seen in large reciprocal crosses. It might be
overall timing offlowering (i. e. one cross being a little later than the other),
or the average height may be 3 or 4 inches taller overall. But more often the
reciprocal cross will be as different as chalk and cheese. Colour, growth, form,
you name it. Usually the cross one way will be exceptional and the other way
will be very ordinary."
He went on to say that form and growth habit seem to be
determined by the pod parent, while the pollen parent is more likely to
influence the color. The key to noticing these differences lies in the size
of the reciprocal crosses. The greater the number of seedlings, the more
likely one is to observe the tendencies Blyth has noted. As an example,
Blyth cites the following:
1. Ennoble X Wearing Rubies. "I had about 30 seedlings flower. Every
one of them was ruby red in tones of 'Ennoble' (Ghio 98, TB). There are 4
different ones depicted on the photos. These were the best fou ur and one was
registered as 'Let's Be Brazen' (Blyth 04, TB)."
2. Wearing Rubies X Ennoble. "I had about the same or even more
seedlings flower from this cross. Every last one was either a vibrant bicolour
or amoena. No reddish tones. There are three seedlings depicted (the best 3).
None were named"
Naturally, I found Blyth's observations compelling, so I decided
to test their plausibility. In a telephone conversation with Dr. Laura
Galloway, a plant biologist at the University of Virginia, I questioned
whether Blyth's observations could perhaps have a sound genetic
explanation. She responded with a resounding "Yes!"
In the female reproductive cells of plants there are both mitochondria
and chloroplasts each containing small amounts of DNA passed along to
progeny only through the maternal parent. Chloroplast DNA primarily
affects the efficiency of photosynthesis, while mitochondrial DNA
affects, among other things, respiration. Some of the mitochondrial
and chloroplast genes act alone, while others work in combination with
chromosomal genes to produce traits that will not appear in a reciprocal
cross where there are different forms of the mitochondrial DNA gene
or genes. Dr. Galloway did not have a ready explanation for Blyth's
observation that color seemed to be more influenced by the pollen
parent, but neither did she rule it out. Clearly, more data is necessary
before explanations can be sought.
Once again, I feel compelled to throw down the gauntlet and
challenge breeders, especially young ones with many garden-hours in
their futures, to get busy adding data in this area. What is needed is a
controlled experiment where large reciprocal crosses are performed and
results noted and recorded. Blyth says "usually each season I manage a couple
and I am really interested in overall results if there are 30 or 40 seedlings at
least in each cross." He also mentions that sometimes reciprocal crosses
cannot be made for lack of pollen, male or female infertility, failure of
germination and so on.
Before testing reciprocal crossing for yourselves, check to be sure
that the varieties you've chosen don't arise from the same maternal line
- siblings, for instance, or half-siblings from a common maternal line,
as they would have identical maternally inherited mitochondrial and
chloroplast DNA.
lauriemorningglory said: Lyn, in many flowering plants, some genetic material is passed to the "children" only through the "mother" plant. There are genes in chloroplasts and mitochondria within the cells contributed by the "mom" but not in the pollen. Could be true in iris, but in looking around a little online, I didn't find confirmation of that. I did come across a reference that could have some interesting info, if you can find the article from an old AIS Bulletin:
October 2007 - The Value of Reciprocal Crosses in Bearded Irises - Blyth data Presented by Pat Otterness, Virginia, p. 86-87.
