PLANT PHYSIOLOGY , Vol 107, Issue 2 535-543, Copyright © 1995 by American Society of Plant Biologists
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BIOCHEMISTRY AND ENZYMOLOGY |
The Lipoxygenase Isozymes in Soybean [Glycine max (L.) Merr.] Leaves (Changes during Leaf Development, after Wounding, and following Reproductive Sink Removal)
D. M. Saravitz and J. N. Siedow
Developmental, Cell and Molecular Biology/Department of Botany, Duke University, Box 91000, Durham, North Carolina 27708-1000
The levels of individual lipoxygenase isozymes in soybean [Glycine max (L.)
Merr.] leaves were assessed during leaf development, after mechanical
wounding, and in response to reproductive sink removal. Native isoelectric
focusing followed by immunoblotting was employed to examine individual
lipoxygenase isozymes. In leaves of all ages, two distinct classes of
lipoxygenase isozymes were detected. One class of lipoxygenase isozymes had
nearly neutral isoelectric points (pls) ranging from pH 6.8 to 7.2. The
other class of lipoxygenase isozymes had acidic pls ranging from pH 4.7 to
5.6. During leaf development, all of the neutral lipoxygenase isozymes and
most of the acidic isozymes were present in greatest abundance in the
youngest leaves examined and declined in amount as leaf age increased.
However, four acidic lipoxygenase isozymes (pl = 4.70, 4.80, 4.90, 4.95)
were more abundant in intermediateage leaves than in either the youngest or
oldest leaves examined. Following mechanical wounding of leaves, these same
four acidic isozymes also increased in abundance both locally and
systemically in leaves from wounded plants. Unlike the specific effects of
wounding on the lipoxygenase isozymes in leaves, reproductive sink removal
stimulated a general increase in most of the acidic lipoxygenase isozymes
in leaves.
