RE: [SpaceAgeRobin] RE: Space Age Genetics

Donald, coming up with an interpretation of SA genetics isn't going to be easy, and data like yours, of one of four seedlings from a known SA having SA character is exactly the sort of info needed, just a lot more of it.
 
I like the looks of that seedling, and especially like the looks of its consistancy.  Are you willing to share it as a breeder?
 
Chuck's suggestion the primary factor in SA inheritance is a weak dominant is probably accurate, judging by the small amount of information from Austin's comments and others.  SA's crossed onto most varieties gives at least some SA offspring.  The non-producers are a minority, in fact, a very small minority.  That suggests a dominant, but a weak one, as rations are never 1 out of 2, the ratio expected from a strong dominant in a single dose on one of the parents, and 3 out of 4 for the dominant present in both parents as one dose, or in either parent in 2 doses.
 
Occasionally there will be a variety that throws a substantial percentage of SA's in a cross with an SA, YAQUINA BLUE being one of them.
 
Yaquina Blue is from Schreiner's seedling L-100A, and so is HONKY TONK BLUES.  The two, however, behave quite differently crossed to the same SA pollen.  YB gave flounces, HTB gave only horned to spooned and a far lower percentage of the seedlings were SA.  Two of those seedlings crossed with each other produced BOTTOMS UP for Mike, a flounced variety.  Interpreting that set of related crosses requires some head-scratching.
 
In the SA inheritance, we may have something analogous to the combinations of Dominant White (using whatever symbol strikes the fancy--it used to be "I"), the Progenitor amoena factor "I(s)", Violanin or Delphinidin pigment (B or whatever), and recessive white (non-B, or "b") of at least two sorts.  This of course ignores the entire plicata allelic series which acts upon B, is compatible with I(s) and both characters can be expressed at the same time, is hidden by I, which as a dominant is not effective on some Delphinidin pigments as much as to others, hence SILVERADO, an "I" white, but described as "bluebird blue."  "I(s)" also does not affect some pigments, either only slightly or not at all.  Romantic Evening is an example.  The fall deep color is an Umbrata effect, not a result of the amoena factor, at least not primarily so.  The border on the falls is the same color as the standards.
 
That is an interactive array of color factors, that were we presented with in raw form would leave us just as bewildered as we are about SA's.  "I" can hide "I(s)" and completely obscure the difference between BBbb and bbbb, which would act very differently in a cross.
 
I doubt the pedigree of THORNBIRD supports the proposition that it is SSSS, four-plex dominant SA.  More likely it is Ssss, with perhaps an epistatic gene along with it--a real possibility, and one which Chapman also suggests.
 
The "S" (Space Age) factor, or primary factor, may well be a weak dominant, analogous to the dominant amoena, as in I(s)--Kevin's theme or Melodrama types, I(s)I(s)--normal amoenas, I(s)I(s)I(s)--Last Laugh, and all four, I(s) I(s)I(s)I(s)--Fred Kerr's banded beauties, the "Emma Cook" type.  Fred Kerr is fairly sure this is what he observes in his crosses.  The pedigree of Emma Cook, the first TB of this type, allows for the amoena factor to come in from more than one source.  CONJURATION is an example of this four-fold I(s) combined with S, space age, factor.
 
With S, one dose might be the BS or BSE as in ADVANCE GUARD and many others; SS, two doses, as in Thornbird, SSS, three doses in spooned, SSSS, four doses in flounced and elaborated flounce with some other factors, perhaps recessive accounting for the variations in these, such as simple horn vs. horn with beard hairs, and so on.
 
This doesn't account for the variation we see in SA expression under different conditions--e.g., GLADIATRIX of Lloyd Zurbrigg being "short horns" displaying a fully developed flounce for Robin Shadlow last year in Nebraska.
 
The entire sequence can be hidden (in analogy to all the variations in blues) by "N" --a normalizing inhibitor in even one dose.
 
I doubt the sequence turns out to be that simple.
 
That's where larger progenies from all the same few crosses will help, especially if carried into the F2.  This will take some serious sorting.  The various Punnett Squares for several combinations of factors (including using Punnett "Cubes" for three factors considered together) can predict ratios, more or less, but the more complex the field, the larger the progenies need to be.
 
Neil Mogenen  z 7  Reg 4  western NC mountains
 
 

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