Re: Yellow leaves
- Subject: Re: Yellow leaves
- From: h*@open.org
- Date: Sat, 15 Feb 2003 13:50:34 -0800 (PST)
Ben:
>So a hosta can never have a hidden yellow gene.
You need to reconsider some basic Mendelian genetics along with some
polyploid genetics. Dominant genes can easily be made to look like
recessive genes and vice versa, and with amphidiploids its very easy
to have fixed heterozygosity.
First of all, you have never said if you believe if the yellow gene is
an inhibitor gene acting to block chlorophyll biosynthesis or if it is
an allele of a gene within the chlorophyll biosynthetic pathway.
If you have a gene "G" for green leaves and an inhibitor gene "I",
then the geneotype GGIi will make yellow leaves look like a dominant
gene when in fact green leaves are dominant but it is the domiant
inhibitor gene that you are really seeing.
If you have a yellow allele for an otherwise green gene, you would
expect that to show up as a recessive allele since it would be
blocking chlorophyll biosynthesis, for example, GG and Gg would be
green and gg would be yellow. In this case it would also be easy to
hide the gg genotype in a fixed heterozygous condition because of the
amphidiploid nature of hostas - GG on one genome and gg on the second
genome. A rare homeologous cross over could eventually bring out the
recessive genotype.
Make the active gene a dominant complimentary gene and the inhibitor
gene a dominant complimentary gene and you can come up with some
really interesting cases.
Joe Halinar
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