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Re: Genetics question


Joanne,

I will attempt to answer your question...why are most hostas green if
yellow is dominant and green is recessive, as indicated by Jim Wilkins
at Hosta College? A little information is not dangerous...with a little
more information, then both kinds and amounts add to each other and 
things can be easily explained.

Let me preface with acknowledgment that I am not a Genetist but I can
read what Genetists write about. I can also interprete and explain in
the English language what they write about. Some Genetists can't do that
very well.

A correct answer must involve the facts.
The facts must be interpreted correctly.
The interpretation in English must be adequately correct and clear to
transfer the facts to the reader.
Since no Genetists have attempted to answered your question, a
non-Genetist will try to answer it. 

Vaughn has published on color in hostas being attributed to plastids. He
has also published that green color as a nuclear gene expression is
recessive and that yellow color is dominant. So you ask why are most
hostas green?

Green color in hostas is due to the presence of chlorophyll molecules in
chloroplasts within cytoplasm of cells. The destruction of chloroplasts
to some degree allows associated carotenoid pigments to be
observed...light of specific wave lengths is reflected from tissue which
appears yellow in color. The presence of leucoplasts without
chloroplasts may make tissues appear white in color. So the three colors
which may appear in hostas are green, yellow and white.

According to Vaughn, yy is the genetic symbol for green which is
recessive
                     Yy is the genetic symbol for heterozygous yellow
which is yellow in color such as in H.'August Moon'.
                Double YY is dominant for yellow which is lethal

A gene which is dominant "does" something. In this case that "something"
is to destruct chloroplasts to some degree, leaving the color of
associated carotenoids to be observed. A double dose of the dominant
gene kills seedlings at an early age and we do not observe many of them.
The green seedlings compete in nature better than the Yy yellows. They
populate better, faster and more efficiently in nature so we see more of
them in nature. In the garden with human selection interference,
population densities of greens and yellows are altered, depending upon
the whims of the gardeners, in which case we may see more yellows than
observed in nature.

Does this make sense Joanne?  

Jim Hawes


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