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Re: sports


>Sports can arise different ways 

Been there, done that!  Your rule of thumb for sporting in hostas 
isn't worth much, except for chimera rearrangements.  The average 
mutation rate of one in a million is far too low to explain sporting 
in hostas and mitotic crossing over is so rare that is can be 
dismissed out of hand.  Even in bacteria and fungi where mitotic 
crossing over has been demonstrated they had to devise screening 
methods to screen hundreds of millions of individual to pick out a few 
rare mitotic cross overs.  I have no idea why you think it is a common 
phenomenon in hosta.  I don't know of any mitotic crossing over that 
has ever been demonstrated in higher plants and yet you casually 
assume it is a everyday occurance in hosta!  Mutations are a random 
event, but yet in hostas we see the same sports showing up.

Ben, variegation in hosta is under genetic control, although it may 
not aways be expressed.  You don't get seedlings germinating 
variegated with out there being some genetic control for variegation. 
There is no need to assume mutated plastids for genetically controlled 
variegation.  Actually, it's not difficult to figure out a mechanism 
for how this can happen.  If you look at a GOOD plant anatomy book 
like Esau, and read the chapter on embryo development you should be 
able to easily see how a variegated seedling can arise, especially so 
considering your experience with fruit flies.  

Much of the sporting we see in hostas can easily be explained by 
transposable elements that have specific locations where they attach 
themselves.  A combination of transposable elements and a genetic 
variegation control mechanism makes a nice working theory for hosta 
sporting.  All that is necessary is to turn off chlorophyll synthesis 
or surpress chloroplast development in one of the histogenic layers.

Now Ben, when you write this up for the Hosta Journal as your idea 
would you please at least give me a little credit!

Joe Halinar

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