PLANT PHYSIOLOGY , Vol 101, Issue 2 373-383, Copyright © 1993 by American Society of Plant Biologists
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MOLECULAR BIOLOGY AND GENE REGULATION |
Tobacco and Parsley 4-Coumarate:Coenzyme A Ligase Genes Are Temporally and Spatially Regulated in a Cell Type-Specific Manner during Tobacco Flower Development
S. Reinold, K. D. Hauffe and C. J. Douglas
Department of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
The enzyme 4-coumarate:coenzyme A ligase (4CL) plays a key role in
phenylpropanoid metabolism by supplying the precursors (coenzyme A esters
of cinnamic acid derivatives) used for the biosynthesis of diverse natural
products, many of which play functional roles in floral organs. In this
study, we used in situ hybridization and histochemical localization of
[beta]-glucuronidase (GUS) activity to define in detail the temporal and
spatial patterns of 4CL-1 expression during tobacco flower development.
Sectioned flowers from tobacco plants transgenic for a complete copy of the
parsley (Petroselinum crispum) 4CL-1 gene were hybridized to probes that
distinguished between 4CL-1 transcripts and endogenous tobacco 4CL
transcripts. Both probes hybridized with similar cell type-specific
patterns to carpels, anthers, petals, and sepals, and the sites of
hybridization varied during flower development. The sites of hybridization
generally coincided temporally and spatially with sites of 4CL-GUS
expression, suggesting that most of the expression patterns are regulated
by 4CL-1 promoter sequences, but lack of correlation between sites of 4CL
mRNA accumulation and GUS activity in portions of the petal suggest that
downstream sequences may mediate some aspects of developmentally regulated
4CL-1 expression. These results indicate that the introduced 4CL-1 gene
correctly responds to endogenous tobacco developmental signals and
demonstrate complex temporal and spatial patterns of expression during
floral organ differentiation.