PLANT PHYSIOLOGY , Vol 113, Issue 2 419-424, Copyright © 1997 by American Society of Plant Biologists
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GENE REGULATION AND MOLECULAR GENETICS |
Sugar-Dependent Gibberellin-Induced Chalcone Synthase Gene Expression in Petunia Corollas
D. Moalem-Beno, G. Tamari, Y. Leitner-Dagan, A. Borochov and D. Weiss
The Kennedy-Leigh Centre for Horticultural Research, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel
The induction of anthocyanin synthesis and anthocyanin biosynthetic gene
expression in detached petunia (Petunia hybrida) corollas by gibberellic
acid (GA3) requires sucrose. Neither sucrose nor GA3 alone can induce these
processes. We found that GA3 enhances sucrose uptake by 20 to 30%, and we
tested whether this is the mechanism by which the hormone induces gene
expression. Changing the intracellular level of sucrose with the inhibitors
p-chloromercuribenzenesulfonic acid and vanadate did not inhibit the
induction of chalcone synthase gene (chs) expression by GA3. Growing
detached corollas in various sucrose concentrations did not affect the
induction of the gene but did affect its level of expression and the level
of anthocyanin accumulated. Only metabolic sugars promoted GA3-induced
anthocyanin accumulation. Mannitol and sorbitol had no effect and
3-O-methylglucose only slightly promoted chs expression and anthocyanin
accumulation. Our results do not support the suggestion that sugars act as
specific signals in the activation of anthocyanin biosynthetic gene
expression during petunia corolla development. We suggest that sugars are
essential as general sources of carbohydrates for carbon metabolism, upon
which the induction of pigmentation is dependent.
