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.
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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