PLANT PHYSIOLOGY , Vol 110, Issue 4 1275-1282, Copyright © 1996 by American Society of Plant Biologists
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DEVELOPMENT AND GROWTH REGULATION |
Leaf-Mediated Light Responses in Petunia Flowers
S. Moscovici, D. Moalem-Beno and D. Weiss
The Kennedy-Leigh Centre for Horticultural Research, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel
In the present work we studied the role of light in the regulation of
flavonoid gene expression and anthocyanin synthesis in petunia (Petunia
hybrida) corollas. We found that light is required for chalcone synthase
gene (chs) expression, anthocyanin synthesis, and growth of detached and
attached petunia corollas. Although direct illumination induced chs
expression, pigmentation, and elongation of the detached corollas,
irradiation of green leaves or sepals played the main role in the attached
corollas. The duration, intensity, and spectrum of the light reaction
suggest that phytochrome-mediated high-irradiance reactions are involved in
the regulation of corolla development. Using the photosynthesis inhibitor
3-(3,4-dichlorophenyl)-1,1-dimethylurea, we showed that photosynthesis does
not significantly contribute to the leaf-mediated light responses. When
sepals were removed or covered. [14C]sucrose up-take by the corolla of
detached intact flowers was inhibited. The results of this study suggest
that light is perceived by leaves and sepals and enhances corolla sink
activity, elongation, pigmentation, and chs expression. The role of leaves
and sepals in the light regulation of petunia corolla development is
discussed.