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Re: Rainbow Aril/AB #9 - Wm. Mohr

  • Subject: Re: [iris-photos] Rainbow Aril/AB #9 - Wm. Mohr
  • From: Robt R Pries rpries@sbcglobal.net
  • Date: Wed, 3 Dec 2003 12:24:20 -0800 (PST)

Neil is basically correct in his assertions about ‘William  Mohr Giant’ but I think he has overlooked one possibility that seems to be the best explanation for all the characters discussed. Sports are changes that arise during regular cell division (mitosis) a process that is normally incredibly stable. Usually the sport is a one gene difference often allowing expression of a new color. But what if in ‘William Mohr Giant’ a different  type of mutation occurred, whereby during mitosis a cell doubled its chromosome but failed to divide, if it then began normal mitotic divisions it could produce a tetraploid plant. Tetraploids are often larger than their diploid analogues, this would explain the giant. But tetraploids coming from formerly sterile adults can suddenly produce fertile pollen and eggs.  This would explain the sudden increase in fertility. In this case ‘William Mohr Giant was probably a conversion to tetraploidy and not what we normally think of as a sport. It is a shame this plant is no longer with us it might have been very useful.

Neil A Mogensen <neilm@charter.net> wrote:
Francesca asks:
"If it is a sport, how does one treat it in classifying it. What is a sport effectively? Have there been other sports and how were they treated in the realm of registrations? Can someone throw light on this?"
Neil responds:
There have been a number of sports registered, such as those that originate from Honorabile, including Kalidoscope (which may or may not be identical to "Joseph's Coat"--originally an alternate name, but I've been told there are clones circulating where each of the two names is attached to distinctively different cv's).
One sport I know of was used in Schreiner red-bearded white breeding and simply dubbed
"white sport of May Hall" and not registered or offered for sale.
I posted a note about sports on Iris-talk (I think) that will be reprinted in the Spring Tall Talk with a few minor changes.  For that reason I don't feel free to copy the text here.  The essence of it, however, is that a "sport" is a genetic variant of a cv, arising not from seed but from a scion or division from the original, is stable and distinct from the original in some manner.
I had a plicata sport once from CLARA NOYES.  Clara herself had a butterfly-wing veined pattern all over the fall.  I was very careful to check when I dug and divided.  The bloomstalk of the plicata arose from a rhizome that broke off from a rhizome of the normal Clara Noyes.
As to "William Mohr Giant" the assertion that fertile pollen was produced at times did not lead to any registered progeny as far as I know.  Fertility would NOT occur in a diploid (onco x diploid TB) in any form other than by fertilization of unreduced gametes, which Wm Mohr did rarely produce.  The number of pollenizations made to get the fairly good number of offspring must have been astronomical.  I know that I made many, many attempts and never got any seeds.  "William Mohr Giant" showing fertility says to me that it could NOT be a sport---the chromosome count would have had to be doubled for fertile pollen to be produced--ever. To get a  doubled-chromosome William Mohr would have required very tightly controlled application of colchicine or one of the herbicides that had not been yet developed in 1951.  I know of no occurances of doubled chromosomes occuring other than with very tiny seedlings, such as Orville Fay, Dr. McEwen and such people have used with various plants--hems, Siberians, LA's (Kevin Vaughn) and JI's.  No published work that I know of describes techniques for use with adult plants.  I only wish there were--and we had doubled, fertile OYEZ or some other of the diploid hybrids of the same type as William Mohr that came from the early work of C. G. White.  For such an occurance to occur spontaneously boggles the imagination.
Close inspection of the beard in the photo of "William Mohr Giant" suggests a flower 3/4 tall bearded to me.  I believe the form and pattern displayed also resembles a "Mohr" more closely than it does the original William Mohr.  Let me add I speak from vast ignorance and large opinion without much humility attached.
Neil Mogensen   z 7  western NC

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