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Re: Unusual Sport

  • Subject: Re: Unusual Sport
  • From: Jim Hawes <hawesj@atlantic.net>
  • Date: Mon, 30 Apr 2001 09:14:57 -0400

Bill Nash and others reading,

My brief diagnosis of the possible causes for the unusual variegation pattern in Pat Mora's sport of Embroidery described what may have happened. The "sorting out" process occurs in  a hosta sport in transition from one form to another form. It is not stable while in transition. Only a periclinal form of a chimera is relatively stable. If it is a periclinal form, the "sorting out" has become completed and the periclinal form will remain as such until it "changes" again. These changes are either nuclear mutations or plastid mutations which may modify chlorophyll synthesis capabilities within cell initials in the meristem apex.

These comments, BTW, are the summary comments from our discussion on Origin of Sports which took place during Feb and part of March,  2001 on hosta-open. They are based on the research findings during the last 20 years  or so by several researchers  in the US, which we have been characterizing as "conventional wisdom". These causes differ completely from those mentioned ( but not described very well) by Zonneveld in his Rule of Thumb theory, written about at least  three times in Journal articles.in recent years. This theory has  been discredited in our discussions, BTW.. . The interpretations of the conventional wisdom  have been astutely summarized by Dr. Marcotrigiano in his HortScience article ( 1997)  . .entitled "Chimeras and Variegation: Patterns of Deceit". I have personally been involved since 1995 in trying to  initiate a better understanding of the processes inherent in the changes which occur in hosta sports within groups of cultivars. I will continue to be helpful if I can,  in bringing about a better understanding of  hosta sports.

I have begun to think that the scientific  processes involved may be scaring off people from a better understanding of sports. If this is the case, we can change this opinion with some repetition of the descriptions of  the processes involved. For example, do many people understand what "sorting out":of homoplastic or heteroplastidic cells means?  or what  cell initials in meristems are ? or the LI and LII layers? or tissue switching involving displacement or replacement? or what happens when a mutation occurs? I thought not!!!.. But these processes and their understanding are necessary to understand sports and how they change in our gardens. How many people are really interested in learning about this dull stuff? There will be a discussion  on some of this subject matter on Thursday evening during the Convention under Dr. Lois Girton's direction  I wish I could attend, but unfortunately I can not. But anyone with any interest should certainly attend.

Jim Hawes. 
 
 

Bill Nash wrote:

 Jim et al ...this is coming to you from a simple dirt gardener, who is not very well versed in scientific training.   My complements, are extended on your well thought out analogy pertaining to the cause & effect probability of Pat Mora's hosta mutation.

*ONE wee'WILL'question! ..if I may?*
Do you suppose: this is a stable genetic factor; and thereby, the leaf characteristics will be maintained?  ../OR: due to this being an unstable quirk of LI/LII arrangements therefore, the plant can revert to it's former self in the next eye-cycle of growth?

ONE MORE question! ..Would leaf bud-cuttings be in order, to preserve the leaf nature?

HOSTA'lly yours

-=>O<=-
"come on Sunshine"
aka .."Bill Nash Guelph Ontario Canada" <raffi@sympatico.ca>
<<--- regarding original email below --->>
At 11:45 PM 04/29/2001 -0400, the Wizard of Awes (Jim Hawes); Jimbo'wrote:

Bill and other unusual sports,

The photo of Pat Mora's sport is indeed different. I have tried to come up with some possible explanations for the unusual pattern of LI and LII tissue. Let me start off the discussion of possible causes for the variegation pattern with several assumptions which may affect the analysis of the causes.

Assumptions:

1. That the parent of 'Embroidery' (Aden) is Green Velveteen and not the otherway around as stated in the HostaSports.com Library
.
2. That the ruffled edges of 'Embroidery' is due to the presumption that it may be a 4-2-2 cytochimera which causes the ruffling in the green outer edge. I suggested this in a talk given in 1997 Winter Scientific Meeting in Chicago. This is speculation, please understand.

3. That the LI/LII tissue cytochimera may have been induced by radiation by the originator. This also is pure speculation on my part, but may be a reasonable assumption.

4. That 'Embroidery' has been propagated widely by now. I know that two labs have propagated it (Scolnick and Ventatesh in Florida for Khlem) and perhaps Shady Oaks also. The more it is propagated, the more variable the end product may become  because of more chances for mutations of several types..

5. That several mechanisms may have occurred within the plant tissue undergoing micropropagation. These mechanisms must have occurred in an exact sequence to give the specific pattern of variegation which has been displayed in the photo. Some mutations may have occurred without being observed in tissue culture.

6. That LI and LII layers remain distinct with 'Embroidery' while in tissue culture with the exception that tissue displacement/replacement may have occurred  at one specific time while the cultivar was  being micropropagated.

With these assumptions being accepted, the following sequences of changes may have occurred to explain the pattern of variegation observed in Pat Mora's unusual sport:

Step 1. Green Velveteen may have undergone a chloroplast mutation which created upon complete sorting out of unmutated and mutated plastids, a periclinal sport with a green center and a white edge.

Step 2 . A tissue transfer took place with cell initials of LII displacing the position of LI, and LI replacing the position of LII. The chimera now has a green edge and a white center.

Step 3. A mutation creating a 4-2-2 cytochimaral sport may have been created in a major cell initial in the unmutated green LII cell, creating a green ruffled edge. The media portion of the leaf was unchanged, being white..

Step 4. After a number of years of micropropagation, a nuclear mutation may have occurred changing the ability of one cell which happened to be a cell initial in the apex of the meristem within the white LI tissue to begin again to synthesize chlorophyll once more in a portion of the white tissue layer. At the time of the photo, incomplete sorting out is suggested as the current situation,  since some of the tissue is striated with alternating patterns of green and white tissue on some leaves and a larger area of green  cells  on one of the other  leaves appearing, giving the LI layer,  cells of two different types,  green and white.. . I would not be surprised to see more green tissue next year with the white area of the leaves   being reduced in size in future years.

How is that for a diagnosis? Of course, other mechanism changes may have occurred instead of those I have suggested. Aren't hosta wonderful? Just about anything may have occurred.

Jim Hawes
 
 

Bill Meyer wrote:

Hi Sports Fans,         The picture attached here was sent to hostapix by Pat Mora. It shows a division of 'Embroidery' in which a green center is appearing inside the whitish center, which is something I've only seen before in 'Royal Tiara'. Given that we understand Hosta to have only two layers, how can we explain this? Has a third layer come into existance through mutation? Or is this new tissue some L1 that has become trapped inside the L2? This is one of the strangest things hostas do. The appearance of a third color in a hosta leaf is not uncommon, but this usually occurs as streaking or patches of another color. What does it tell us that it apparently can form a stable-appearing pattern?                                                                                .............Bill Meyer




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