Re: Genetics question

Thanks Jim, it does help.  I would assume the green would be more vigorous
because of the greater amount of chlorophyll. I guess I would just be
curious as to why the Y gene wouldn't eventually have been
lost from the population if the greens are yy and out grow the others.  With
controlled hybridizing it could obviously be maintained, but without human
intervention would it be lost?
Joanne
jopyz@earthlink.net
-----Original Message-----
From: Jim Hawes <hawesj@gcnet.net>
To: hosta-open@mallorn.com <hosta-open@mallorn.com>
Cc: hawesj@gcnet.net <hawesj@gcnet.net>
Date: Monday, March 15, 1999 9:44 AM
Subject: Re: Genetics question


>
>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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