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RE HYB:Umbrata pattern

I have checked a few references and have a few points of interest.

The comment re multiple dossages of I and mortallity was offered as an 
explination for no known/obseved multiple dosages. It never seemed to go past 
speculation stage. A lot of the data on white/yellow from a cross of an I 
with a blue iris never gave the expected ratio. Actually according to numbers 
in Randolph's book the numbers were seldom 1/2 but more often 1/4 or  3/4 
Reduced anthocyanin. There are lots of partilly reduced anthocyanin plants 
with I factor. A cross of an I plant with an aphylla (especially on one of 
the darker clones) usually gives a lighter colour sometimes a light blue and 
sometimes darker, but usually all plants same colour.

There is a cross of   Vengence ( a plicata) X (Chantilly (very light 
lavender) X aphylla "Dark Violet ) which gave  100% plicata yet the seedling 
from Chantilly X Dark Violet wasn't a plicata  (likely a violet ). Reported 
by Lynn Markham in Signa 1995 pg 2034-2036.  

All of these suggest to me a dosage effect of both AE and any of the 
reduction genes whether plicata or recessive or dominant reduction of 
anthocyanin. Amounts of AE were not considered in these crosses. I would 
suspect that if AE dosages were accounted for and dosages of I were accounted 
for we could get the predictable  results that were not forthcoming 

The Emma Cook pattern also offers some information on this. All of the 
dramatic patterns with a narrow edge seem to come from multiple Is but none 
of these seem to be AE. The ones that seem to have AE have a much much wider 
band of anthocyanin on falls. There seems to be no EC types with a narrow 
band of anthocyanin that also has any AE. 

The only question that remaings for me , based on the information I have 
currently) is the interactions of dosage levels. That is what does a plant 
look like with 4 AE an 1 I, 2 I , 3 I and 4 I dosages etc. It seems that 
there is an interaction effect of some kind.

Chuck Chapman

There had been some speculation that the "I" Dominant anthocyanin inhibitor 
does not build up beyond two doses or so, as anything more is fatal.  This 
was speculation years and years ago--back when Jean Stevens was active and 
contributing to the *Bulletin* from time to time.   She speculated that the 
possible exception might be PINNACLE, as she never saw any 
anthocyanin-expressed seedlings from it.

All other dominant I-types seem to produce at least some 
violet-blue-expressed offspring, and I don't mean the cold whites that get 
called "blue" like SILVERADO.  That cv is an extreme example of an I-white 
with a lot of pigment penetrating through--probably due to the AVI issue.   
One leg of its ancestry is from the Schreiner black breeding, so there is 
certainly enough *aphylla* ancestry to account for the presence of 
considerable AVI-enhanced anthocyanin.

A couple of other Romantic Evening crosses may be of interest--

Skywalker X RE had only a few seedlings germinate from a fairly small 
pod--about 27 seeds as I recall.  So far, one dark self and three odd 
shot-silk patterns like Honky Tonk Blues and Skywalker have--where both the 
standards and falls have a lighter pale blue to medium blue ground, with a 
"shot silk" flush or shadow of darker pigment through the flower, mostly in 
the center of the petals.   This same effect shows in OLYMPIAD, from a rather 
distantly related line.

The ancestry of Olympiad involves several generations of inbreeding, really 
tight inbreeding in fact.

But no bitones or bicolors have bloomed from the Skywalker cross.  They may 
be concealed behind the light-blue ground color which I suspect is a single 
dose "I" with pigments penetrating through the inhibitor, which I also think 
is the case in Skywalker.   Relative to the AVI enhancement factor, "I" acts 
like a rather weak dominant, while with normal Violanin without the AVI 
enhancement, it is a fairly strong one.

Along with this Olympiad-HTB shot silk effect, the irises with white to light 
blue with very dark blue beards seem to be in the same kind of situation, 
with enhanced anthocyanins penetrating through the "I".  What a puzzle!

If we had some idea of what kind of enzyme catalyst the dominant "I" was, it 
might be interesting and helpful to explain all this.  Because the 
anthocyanins remain as colorless leucoanthocyanins, it suggests some 
interruption or blockage, or a defective version of one of the necessary 
enzyme catalysts in the anthocyanin synthesis rather late in the sequence, as 
I believe the leucoanthocyanins are not formed until about the last three or 
four steps of the synthesis chain.

Neil Mogensen  z 7 western NC mountains

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