PLANT PHYSIOLOGY , Vol 110, Issue 3 1035-1046, Copyright © 1996 by American Society of Plant Biologists
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GENE REGULATION AND MOLECULAR GENETICS |
Cloning of Wound-Induced Cytochrome P450 Monooxygenases Expressed in Pea
M. R. Frank, J. M. Deyneka and M. A. Schuler
Department of Plant Biology, University of Illinois, Urbana, Illinois 61801
Cytochrome P450 monooxygenases (P450s) mediate a wide range of oxidative
reactions involved in the biosynthesis of plant secondary metabolites
including phenylpropanoids and phytoalexins. To investigate the regulation
of these P450s in the phenylpropanoid biosynthetic pathway of pea (Pisum
sativum), partial cDNAs representing four distinct P450s expressed in pea
seedlings were cloned using a reverse transcription-polymerase chain
reaction strategy. One of the corresponding full-length cDNA clones,
designated CYP73A9, encodes pea trans-cinnamic acid 4-hydroxylase, which
catalyzes the second core reaction in the phenylpropanoid pathway. As
expected from its central role in the production of lignin precursors and
defense compounds, northern analysis of poly(A)+ mRNA demonstrates that
transcripts encoding CYP73A9 are induced appreciably within 3 h after
wounding. A second cDNA clone, designated CYP82, encodes a novel P450,
whose transcripts are also induced in response to wounding at approximately
the same time as CYP73A9 transcripts. Despite the multitude of
environmental stimuli known to induce expression of phenylpropanoid pathway
enzymes, genomic DNA Southern analysis indicates that each of these P450s
is encoded by a low copy number (possibly a single copy) gene family.
