Re: [SpaceAgeRobin] RE: Space Age Genetics

irischapman@netscape.net wrote:
With a partial dominant, it would need 3 or 4 dosages of SA to produce an appendage. The shelf may be either one ote two SA genes. Thus the showing up of 3 or 4 dosages necessary to show appendage would not occur as readily as may be assumed. Also since there is some propensity for SA gene to produce some flower distortion the two dosage plants would tend to be discarded.
Thornbird with this sort of history would likely be 4 dosage SA gene.
A test of this would now involve crossing TB X the plants that seem to "Inhibit" SA or could be 0 dosages of SA. If the partial dominance theory is correct then this cross should produce almost no SA as would the inhibition theory but F2 would sort out in a punnett square analysis. I havn't yet checked if F2 would distinguish one idea from the other.

I hope you let us know so we can design a cross that will have numbers  to be statistically significant. Beard extensions and petaloids are related but different traits.
There are a lot of similarities to the PBF trait. Some growing conditions produce effect, doesn't show up in others in same plant. This is typical of partial dominace and also to multiple allele factors.

and a lot easier to observe than rebloom traits...
Don't dismisss this theory too soon. It's still a viable possibility and the results are not in yet.

Chuck Chapman

"Neil A Mogensen" <neilm@charter.net> wrote:


>
>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.
or a ratio of inhibitor to expressive genes similar to current theories on pattern and color genes.
>
>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.
Besides hormonal triggers based on soil nutrients and climates there are also inherited seasonal triggers. If petaloid developement begins later than beard developement it grows from the beard. If the petaloid starts early enough to extend down what will be the midline of the falls before the beard spine forms then we see flounces seperate from the beard( which may also have an extension either a brush or a more incomplete type of spoon, flounce or antler.) If there is a tie between these three kinds of triggers we see a conglomerate of brushy beard and petaloid protoplasm such as is common in CANARY FEATHERS.

As your SA's bloom take a close look at the beards especially in the throat. Can differentiate between a center beard that becomes an extention and a different type of beard on each side? Is the seperate beard an attempt to start another petal? If this seperate type of beard and accompaning petaloid an attempt at creating another standard? ( many of the species that lead to our modern hybrids did have small scraggly beards on the standards.)

Stay tuned for TOO MANY FLOUNCES an iris that not has flounces but also has falls that that try to split into two fallls.

of course It could also be because I have spent too much time in the weeds around the iris...

Michael M.


>
>This is an onion that will not quickly be peeled.
>
>Neil Mogensen  z 7  western NC mountains
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