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RE:Plicata genetics Part 5

So far I have identified six genotype plicatas and made reasonable connections
with phenotypes (appearence). This has been done by just looking at the MDB
and SDB where the genetics has been somewhat simplified by the luminata and
regulat plicata alleles being restricted to the TB set of chromosomes. When we
move into the Tall Bearded plants there are now  36 genetic combinations. Six
combinations for each pair of genes on each side of a Punnett square. These
are the  six sets allready explored in the SDB. With the SDB we had these 6
sets on one side of the Punnett square and on the other side only had two
glaciata genes (pla pla). When this is actually worked out there is a lot of
duplication and there are only 15 different plicata genotypes. This is still a
large number and leaves nine types yet to identify. Some of these are easy to
identify. There has been a number of articles published on plicata genetics
over the years and good information is available, especially on the glaciata
gene. There has been identified iris plants with one, two and three glaciata
genes, as well as glaciatas with four sets of glaciata genes. In each of these
cases the remaining genes are the regular plicata genes (pl).

"pl pla pla pla" has been shown to be a classic plicata pattern with narrow
plicata rim markings. Examples historically include Los Angeles as well as
almost all MDB regular (non veined) plicatas. April Melody is another of this
pattern that has been identified and more importantly, tested out.

"pl pl pla pla" has been identified as the wider of the two clasic plicata
patterns with SDBs and photos have been posted showing examples of this. TBs
with this pattern have been identified through test crosses are Tea Apron,
Blueberry Trim and Pink Ember. These all show a wider "classic" plicata  then
the cultivars with only one pl gene. For purposes of discussion and refference
I will refer to these as plicata(2), the ones with just one pl gene as
plicata(1) etc. Of note is that some of these varieties have dotting. Tea
apron is a good example of this.

"pl pl pl pla" Plicata(3) some examples of this pattern are Soft Touch,
Roundup and Tiffany. This pattern seems to have a wider margin of plicata
markings, often described as 3/8" plicata edge. 

"pl pl pl pl" Plicata(4) I don't have any clear examples of this, but can
speculate , based on what we have seen so far. The interaction between the
glaciata gene (pla) and the plicata gene (pl) shows that they intreact in a
partial dominance. While the plicata gene is dominant over the glaciata gene ,
this is not a complete dominance. With more glaciata genes present,  the less
anthocyanin pigment is present, or at least distributed over a smaller area.
Thus the glaciata gene in interaction with the plicata gene reduces the width
of the plicata markings or in another way of looking at it, pushes the
anthocyanin more to the edges of the standards and falls. Based on this, what
we should have is a very wide width of classic plicata markings. 

Based on some of these parents, it becomes clear that there is a lot of pla
genes out there in many plicatas. Thus examples of good plicata(4) type may be
hard to come by. Two possible varieties are Jazzebel (pictured in '93
Schreiners's catalog) and Change of Pace in Schreiners '97 catalog.
Some thoughts on plicata(0) or glaciata "pla pla pla pla" plants. As Sharon
McAllister mentioned in her recent post, often a pattern gets stabilized
without a clear understanding of its genetics. A glaciata x glaciata is a very
stable pattern. It will always produce glaciatas. For example, a pink glaciata
X pink glaciata will always produce clean glaciata pink iris without
anthocynin markings. When you think of recent discussions re how to get a
darker pink, I start to wonder if a lot of pink iris (perhaps also yellows)
are really glaciata plicatas. Also Jan clark's remarks got me thinking. How
would you identify, from looking, what was a glaciata plant. The tests of
glaciata X blue iris and back cross to glaciata  has been done and  summerized
in an article (Kidd, "Tetraomic Segregation At the Plicata Locus" in the April
'76 AIS Bulletin") and shown to segregate out in an expected ratio. With these
it was easy to identify the glaciata pl plants as white , while the others
were blue. If you did this with a pink X pink glaciata, and back cross the
phenotype (appearence) would not be a telling factor, the pink glaciata and
non-glaciata would both be pink. The glaciata gene has been around for a long
time and seems to be fairly frequent. When you look at crosses of pinks with
plicatas you often get plicata offspring. Look up a few pink plants such as
Vanity on the iris registery data base to see what I mean. Pink iris plants
seem to be a Recessive Reduced Anthocyanin (RRA). That is the anthocyanin is
removed by a recessive gene that is present four times. This is shown by pink
x pink producing all pink offspring. Glaciata is a Recessive Reduced
Anthocyaningenetic effect, and thus could be the genes producing the RRA. I
would thus speculate that there are a lot of pink iris that are accually 
glaciatas.As hybridizers were working for clearer pink, it would be likely
that some glaciatas would appear. These would be exceptionlly pure of colour.
The next step would be to backcross and sibling cross to stabalize the
pattern. this would result in a stable reproducable pattern. The test would be
very simple. Cross a pink to any plicata. Be prepared to get a number of
glaciatas as well as plicatas. As I mentioned earlier, there are probably few
modern plicatas that don't have at least one pla gene present. 

This could also explain why it is hard to get darker pink iris. For the pink
to be darker you would need a light wash of anthocyanin pigment. This is not
possible if the plants are both glaciata plicatas. Thus to get a dark pink you
would need to cross a pink with a plant with violet (and prefrably pink
cartinoid pigments). Thus you could get the desired plants in first generation
(if lucky) ar more likely in the backcross of offspring to the pink parent or
another pink.

Please feel free to challenge and comment. Some of this is based on known
facts, and some is speculation. All of these comments are based on my own
efforts to understand what I am seeing with plicata genes. Other peoples
comments and observations will help sort out these issues.      

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