Re: yellow color in Hosta


Joe,

Good point.  This would also explain several of the light dependent and
temperature dependent yellow forms.  The sport of Maui Butter Cups we have
starts out all yellow, but the center turns green with time.  It is like the
conversion is only partially inhibited so that with enough time the yellow
(chlorophyll precursor) is fully converted to green (chlorophyll).  It also
is clear that not all my information is directly applicable to Hosta, but
that is why we have these discussions.

Another side of the question, has not been explained adequately.  Most
yellow Hosta that we culture are fully green in the lab, not yellow.  The
lab is a low light environment.  In fact, yellow variegations are often hard
to see in the lab.  The yellow color develops only after the plant is put
into high light conditions.  This would seem to be counter to your argument
about the yellow color and its conversion requiring sunlight.

Thanks,

Jim Anderson

-----Original Message-----
From: halinar@open.org <halinar@open.org>
To: hosta-open@mallorn.com <hosta-open@mallorn.com>
Date: Friday, August 20, 1999 11:32 AM
Subject: Re: yellow color in Hosta


>Jim:
>
>>Ben pointed out to me that yellow sports are not devoid of
>>chlorophyll, but the yellow accessory pigments dominate the color of
>>the leaf.
>
>>Remove most of the chlorophyll and you get yellow, remove both
>>pigments and you get white.
>
>Chloroplast do contain carotene pigments that can give some yellowing
>color ro a leaf.  However, I would suspect that the yellow color in
>most yellow leaved hostas is a late stage precursor to chlorophyll.
>These late stage chlorophyll precursors are yellow colored.  You can
>see this by germinating many seeds in darkness - the cotyledons are
>yellow, not green.  Light is needed to tiger the final synthesis to
>green chrolophyll.  The dominant nature of yellow leaves in hosta
>suggest that this dominant gene is an inhibitor gene of chlorophyll
>synthesis that builds up the yellow precursor.
>
>Joe Halinar
>
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