AR: Signal Characteristics

Message text written by Bill Shear:

>
The other day I brought some arilbred blossoms up to the lab to collect
pollen and looked at the fall surface under the dissecting microscope.
Sure enough, the cells in the signal area had much longer projections than
those not in the signal area.  This gives a kind of velvety nap to the
signal.  The transition across the signal border is rather gradual,
involving 5-6 rows of cells.  The non-signal cells have a projection, but
it is lower and blunter.  Of course, the signal cells also have a different
pigment.  On some "diamond-dusted" varieties, the projections are clear
rather than pigmented, and refract the light like a tiny prism.  This gives
the sparkling appearance of the petal surface in such irises (and
daylilies).
<

This is especially interesting if you can compare species, 3/4-breds,
1/2-breds, and 1/4-breds.  I have come to believe that the inheritance of
signal color is separate from that of signal texture.  Although I've had
considerable success in putting the signal color on quarterbreds, I have
yet to get one with significant texture.

The "diamond-dusting" is another fascinating topic.  I used to think it was
strictly a function of clear surface cells, refracting light as Bill
described -- then I found some with very faint color.   Silver is
especially striking!

>
A great project for a botany student would be to do Scanning Electron
Microscope work on iris petals with different textures (glossy, velvety,
etc.) and determine what, if any, sort of cell morphology these involve.
Retrospectively it might also be possible to work out how such patterns are
inherited.
<

Great idea!  If you can find the student, I can sure supply some theories
to test.

Sharon McAllister
73372.1745@compuserve.com

  


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