isozymes
- To: pumpkins@mallorn.com
- Subject: isozymes
- From: H* E* P*
- Date: Wed, 07 Apr 1999 03:35:03 -0700
You may have looked at the CGC genelists and noticed a high percentage
of the known mutants have names like Shikimate dehydrogenase, Superoxide
dismutase isozyme-1,Triosephosphatase isomerase cytosolic isozyme-2, and
Peroxidase isozyme-1.
These are isozyme mutants. They are harmless to the plant, but require
a properly equipped lab for their identification. For example the last
one is a enzyme which enables a plant to use hydrogen peroxide (a toxin)
in place of oxygen in the energy production pathways.
When you put hyrogen peroxide on a cut finger, you see bubbles because
your catalase enzyme is splitting the hydrogen peroxide, H2O2, and
forminmg water and oxygen molecules. Peroxidases perform the same
important role, but they use the oxygen to in effect oxidize hydrogen to
produce water so no bubbles of oxygen form.
If one found the gene one of these enzymes was linked (one same
chromosome) as a gene(s) for heavy pumpkin in a certain line, then a
grower could plant extra seeds, test the sap of each plant for the
isozyme and and discard the plants that do not have the desired isozyme.
Usually the isozyme if perfectly competent to do its job, but it just
moves differently in starch in an electrial field of 100 or so volts DC.
Notice the mutant enzyme has probably has no effect on pumpkin size; it
is merely a way of picking plants which have the chromosome you have
decided is a good one. You could then put special effort into that
plant.
This is another subject which will be on my website when I find time
to write the pages. Izozymes have been used in breeding work since the
1950s (maybe before that).
--
Harold Eddleman Ph.D. Microbiologist. i*@disknet.com
Location: Palmyra IN USA; 36 kilometers west of Louisville, Kentucky
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