Re: sports
Ben:
>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
---------------------------------------------------------------------
To sign-off this list, send email to majordomo@mallorn.com with the
message text UNSUBSCRIBE HOSTA-OPEN
