PLANT PHYSIOLOGY , Vol 105, Issue 1 385-393, Copyright © 1994 by American Society of Plant Biologists
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MOLECULAR BIOLOGY AND GENE REGULATION |
The LOX1 Gene of Arabidopsis Is Temporally and Spatially Regulated in Germinating Seedlings
M. A. Melan, ALD. Enriquez and T. K. Peterman
Department of Biological Sciences, Wellesley College, Wellesley, Massachusetts 02181
We examined the temporal and spatial expression patterns of the LOX1 gene
during the development of Arabidopsis thaliana seedlings. Measurements of
steady-state LOX1 mRNA levels indicated that this gene is transiently
expressed during germination. LOX1 mRNA was not detected in seed that had
imbibed (T0) but reached a maximum level by 1 d in both light- and
dark-grown seedlings. The induction of the LOX1 gene was not light
dependent; however, mRNA levels were 4-fold greater in light-grown
seedlings. Immunoblot analysis of lipoxygenase protein levels and
measurements of enzyme activity suggested that the induction of the LOX1
gene resulted in the production of functional lipoxygenase enzyme.
Lipoxygenase protein was not present in dry seed or seed that had imbibed,
but was first detected by immunoblot analysis after 1 and 2 d of growth in
the light and dark, respectively. In both cases, lipoxygenase protein
levels remained high for 2 d and then declined. Lipoxygenase activity
paralleled the changes in protein levels. In situ hybridization studies
revealed that the LOX1 gene is transiently expressed in the epidermis and
the aleurone layer during germination. LOX1 mRNA levels were particularly
high in the epidermis of the radicle and the adaxial side of the
cotyledons. These results suggest that the LOX1 gene product is produced
specifically during early germination and plays a role in the functioning
of the epidermis.
