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Nearer my God to Thee!


Hosta Sport Scholars,

I am happy to read recently from Ben "that after this, I follow
Marcotrigiano and will not spend more time trying to convince
non-believers". I am not sure what he means by this. Perhaps Ben will
elaborate on his one-liner...perhaps not.

I speculate that Ben has read Marcotrigiano's "Chimeras and Variegation:
Patterns of Deceit" and now has a new authority . Perhaps we are
reaching a new concensus. Many of us have been studying Marcotrigiano's
works for some time now. It represents the classical research of a group
of scientists located geographically in the NE US.. They have all been
in tune with each other for a number of years, so to speak, publishing
with each other and communicating as scientist normally do.
Marcotrigiano is just one of the many who are prolific writers all
saying about the same and quite often strengthening the work of each
other. So welcome to the discovery you have made Ben.

In summary, my reading of Marcotrigiano is as follows in a very few
words. He claims that chloroplast mutants are the most common cause of
chimeral variegation in plants and not nuclear mutations.Vaughn wrote
about this 20 years ago. Marcotrigiano  explains that heteroplastidic
cells (those with both mutant and non-mutant plastid populations)
develop a cell line which undergo complete sorting-out. If these cells
are in LI or LII tissue, then various forms of chimeras may develop
(periclinal, mericlinal or sectorial)., depending upon the relative
growth  rate of the involved tissues. Further evolution from one type to
another may occur by means of layer switching in LI and/or  LII,
including reversions. Vaughn has reported that one layer growing over a
slower growing layer may also occur.Marcotrigiano's concepts of origins
of chimeras may include other processes in plants which he mentions only
briefly, i.e. .
   2.transposable elements ( known also as "jumping genes")
   3.graft induced chimeras
   4. semigamy
   5. tissue culture synthesis of chimeras.
He does not discuss mitotic recombination as a causal factor. So there
remains just this one factor which Ben insists is a causal factor but no
one else mentions. The fact that mitotic recombination may exist in some
plants on occassions , such as represented by  the photo of a tobacco
leaf which had two white spots arttributed to somatic crossing- over of
a  chromosome in a cell of the epidermis,  is a far stretch that mitotic
recombination as a cause of green edges on yellow hosta leaves.

But we are getting closer. We now are reading the same authority's
writings.

Jim Hawes

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