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RE: Analysis of MV's sedlings Part one Tangerine

  • Subject: [iris-photos] RE: Analysis of MV's sedlings Part one Tangerine
  • From: "Neil A Mogensen" neilm@charter.net
  • Date: Sat, 15 Jan 2005 04:58:10 -0500

It may relevant to recall the parentage proposed for Dr. Loomis' SQ-72, later registered by Melba Hamblen as PIKES PEAK PINK.  It is suggested it's parentage is (Purissima X Seashell).
Purissima or any of its immediate descendants not from crosses involving 4-plex "t" suggest that rare segregates of a one-dose t factor may be present. 
Keith Keppel, if I recall correctly, is somewhere remembered as suggesting the t-factor came into modern tetraploids through KASHMIR WHITE.  If so, it is possible one dose t might be present in any blue or white, and, with the degree of inbreeding among KW's descendants, infrequent but possible two-dose blues or whites may occur.  I know of none.
The factor, judging by recent studies about carotene synthesis in leaf tissue chloroplasts, which *may* apply to iris petal plastids, suggest that Lycopene occurs <before> either alpha- or beta-carotene, the alpha- form converted from Lycopene by converting the left-end form of Lycopene to the Carotene, and the beta-Carotene a result of this same enzyme working together with another converting that same end of Lycopene's molecule to the Carotene form in a manner slightly different from alpha-Carotene.
Thus, t is an epistatic factor (a factor from another locus acting upon a synthesis sequence), and enters into the sequence from Phytoene to beta- and alpha-Carotene by interrupting this step from Lycopene to our more common Carotenes when present in four doses.
The epistatic t could be carried along in the complex blue breeding by Schreiners (as well as others) without visible expression, as the only Carotenes present have been in the beard.  Phenotypically expressed tangerine beards on blues where the Carotenes are only weakly present in beards and a few haft lines hidden under the standards could easily be overlooked in the thousands of seedlings grown by the Schreiners each year.
This may or may not be relevant to your thinking, Chuck.  I offer the above only because I think it <may> have relevance.
Neil Mogensen  z  7 western NC mountains

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