PLANT PHYSIOLOGY , Vol 113, Issue 3 951-959, Copyright © 1997 by American Society of Plant Biologists
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GENE REGULATION AND MOLECULAR GENETICS |
Regulation of the Cinnamate 4-Hydroxylase (CYP73A1) in Jerusalem Artichoke Tubers in Response to Wounding and Chemical Treatments
Y. Batard, M. Schalk, M. A. Pierrel, A. Zimmerlin, F. Durst and D. Werck-Reichhart
Departement d'Enzymologie Cellulaire et Moleculaire, Institut de Biologie Moleculaire des Plantes, Centre National de la Recherche Scientifique, 28 Rue Goethe, 67000 Strasbourg, France
trans-Cinnamate 4-hydroxylase (C4H) is a plant-specific cytochrome (P450)
that is encoded by the gene CYP73A and catalyzes the second step of the
multibranched phenylpropanoid pathway. Increases in C4H activity in
response to physical and chemical stresses have been well documented, but
the mechanism of these increases has never been studied in detail. This
paper reports on the regulatory mechanism controlling C4H activity in
Jerusalem artichoke (Helianthus tuberosus) tubers in response to wounding
and chemical treatments. We compared induction of C4H and other
P450-catalyzed activities. C4H was moderately induced by chemicals relative
to other P450s. Increases in enzyme activity, C4H protein, and transcripts
were quantified and compared in tuber tissue 48 h after wounding and
chemical treatments. Our data suggest that induction of the enzyme activity
results primarily from gene activation. Time-course experiments were
performed after wounding and aminopyrine treatment. Compared with wounded
tissues, aminopyrine triggered an additional and delayed peak of transcript
accumulation. The timing of the induced changes in activity, protein, and
transcripts confirms that C4H induction results primarily from an increase
in CYP73A1 mRNA, in both wounded and aminopyrine-treated tissues. However,
posttranscriptional mechanisms might also contribute to the regulation of
C4H activity.
