Re: Discussion on Origin of Sports

Andrew:

I didn't mistake what you said.  When writing to a group like this I 
try to not use too much terminology that is scientific jargon, but I 
can't make it too simple.  Sometimes one scientific word can take the 
place of several sentences.  I figure that not everyone is going to be 
eating up this discussion, and those who are interested but don't have 
a scientific background probably know how to read and can look up 
terms they don't fully understand, or even ask for further 
clarification.

Jim:

Back to where I left off last night.  I think we can dismiss a few 
ideas for variegation as being unlikely, and we can accept that at 
least some variegation is mutated chloroplasts.  What I don't have a 
good answer for is that L1-L2 variegation that shows up when the seeds 
germinate.  And the other thing I don't have a good answer for is the 
different sports that can and do show up from existing variegated 
hostas.  If variegation was the result of only mutated chloroplasts, 
then we should only see at best 5 possible sports from L1-L2 shifting 
and rearrangment.  If we start with a albomarginata type then we can 
get an all green form, an all white form (dies), a 
albo-mediovariegated type or a streaked form.  Allowing for some minor 
differences because of growth rate due to lower photosynthesis in the 
non-green parts, these plants should pretty much look alike.  However, 
we see many different sports showing up that have changes in addition 
to the variegation patterns.  One of the experiments I am trying to do 
is to induce sports and then take those sports and induce more sports 
and see how these different lines relate to each other.  We can't be 
getting these sports showing up that also have major changes in 
phenotypes unless there is something else going on.

My own hunch is that transposible elements are playing a role or there 
is some control mechanism at work that is linked with histogenic layer 
formation.  The histogenic layers are formed fairly early on in the 
development of the zygote.  It's possible that genes for chlorophyll 
synthesis or other regulator genes are turned on or off at this time. 
 Transposible elements seem to play a role in the streaked variegation 
in some flowers, so I don't see why they couldn't also play a role in 
hosta variegation.  The problem we face right now is that we really 
don't have enough knowledge to say anything specific.  This is why I 
think we need some LONG term studies.  It may be possible that some of 
us who are interested in this can cooperate somewhat and report on 
results we observe this year when hosta seedlings start to germinate. 
 

Joe Halinar

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