Auxins

Ellen Sutter fzsutter at rocky.ucdavis.edu
Mon Jan 9 19:53:01 EST 1995


Robert Mcgehee (TEJU87B at prodigy.com) wrote:
: I'm doing a science report/project on plant hormones especially auxins.  
: I have been doing some research on the field and there are two topics 
: that I do not understand.  The first is apical dominance.  If a bud is 
: removed why would the level of auxin drop in the main stem and why would 
: the adjacent lateral buds begin to grow?  What triggers this?  Isn't it 
: correct that the auxins that were causing the removed bud from growing 
: lied in that bud?  If so wouldn't the auxins also be removed with the bud?


: Another topic I don't seem to understand is this:  If one was to remove 
: all of the seeds on one side of a strawberry, the strawberry would not 
: develope as normal on that side of the strawberry.  Does each seed 
: release auxins for their particular region of the strawberry?

: Thanks

: Robert McGehee


Actually you are correct about the auxin.  When the terminal bud is
removed, there is a signficant reduction in auxin available to the rest
of the plant because the source of auxin (the shoot tip) is no longer
present. Thus, the amount of auxin in the lateral buds drops and these
buds can now grow.
You are also correct about the second question.  The auxins present in
the seeds of the strawberry induced the growth of the fruit.  If they are
present on just one side of the fruit, then just that side grows.  This
was a major experimental finding by J. Nitsch.
        Ellen Sutter
        UC Davis





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