PLANT PHYSIOLOGY , Vol 108, Issue 1 199-202, Copyright © 1995 by American Society of Plant Biologists
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BIOCHEMISTRY AND ENZYMOLOGY |
Allene Oxide Synthase and Allene Oxide Cyclase, Enzymes of the Jasmonic Acid Pathway, Localized in Glycine max Tissues
T. D. Simpson and H. W. Gardner
United States Department of Agriculture, Agricultural Research Service, National Center for Agricultural Utilization Research, Phytoproducts Unit, Peoria, Illinois 61604
Because jasmonic acid regulates a number of processes, including the
expression of vegetative storage proteins in soybean (Glycine max L.)
leaves, the relative activity of a specific portion of the jasmonic acid
biosynthetic pathway in soybean tissues was examined. Allene oxide synthase
and allene oxide cyclase were examined because they constitute a branch
point leading specifically from 13(S)-hydroperoxy-9(Z), 11(E),
15(Z)-octadecatrienoic acid to 12-oxo-phytodienoic acid, the precursor of
jasmonic acid. From growing plants, seed coats (hila plus testae) of green
fruits (38 d post-anthesis) were most active, eliciting about 1.5 times
greater activity on a per milligram of protein basis than the next most
active tissue, which was the pericarp. Leaves from fruiting plants were
only one-seventh as active as seed coats, and activities in both immature
cotyledons and embryonic axes were very low. No activity was detected in
any part of stored, mature seeds. After 72 h of germination of stored
seeds, a small amount of activity, about 4% of that in immature seed coats,
was found in the plumule-hypocotyl-root, and no activity was detected in
the cotyledons. The high levels of jasmonic acid biosynthetic enzymes in
soybean pericarp and seed coat suggest a role for jasmonic acid in the
transfer of assimilate to seeds.
