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RE HYB:Umbrata pattern

  • Subject: [iris-photos] RE HYB:Umbrata pattern
  • From: "Neil A Mogensen" neilm@charter.net
  • Date: Sun, 6 Feb 2005 10:14:43 -0500

Just to be clear, and I think this is what you meant, Chuck--the inhibitor that is hidden in ROMANTIC EVENING, at least I am fairly sure it is, is the I(s) rather than the "I."
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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