[SpaceAgeRobin] RE: Space Age Genetics

Chuck, looking at the family tree for THORNBIRD on the HIPS "Quick Fix" page (or on the Dykes Medal page), doesn't suggest a partial dominant.  Generation after generation of outcrosses to non-SA co-parents produce SA's.
 
If those co-parents carried any of the required make-up for an SA, there would surely have been more "breaks" in seedlings than seem to have occurred.  The only ones I know of are incidents in the Sass seedlings (which is no surprising, since Sass bloodlines are involved in all of the known "breaks").
 
Two other incidents occur in California, one for Mrs. Lohman, the other for Tom Craig.  Other than the appearance of UNICORN in Lloyd Austin's inbreeding seedlings and varieties (ADVANCE GUARD) which display what we are calling "BSE" for beard spine extension.
 
I have seen conspicuous BSEs on a number of irises, especially those from inbred plicata lines (thus strong to Sass ancestry).
 
I think that you are quite right in suggesting that the appearance of SA's is not a single gene, but a combination of at least two.
 
What makes this so complex is that the SA trait is generated right at the beginning of blossom part differentiation in the embryonic bud.  Growth hormones, enzymes that mediate differentiation of falls from the growing tip are undoubtedly involved, and it may be that the SA traits arise from a modification or genetic change in one or more of those.
 
This is an onion that will not quickly be peeled.
 
Neil Mogensen  z 7  western NC mountains

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