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. 1987 Jan;83(1):126–130. doi: 10.1104/pp.83.1.126

Biphasic Fluence-Response Curves for Phytochrome-Mediated Kalanchoë Seed Germination 1

Sensitization by Gibberellic Acid

Roger Rethy 1,2,3, Andrée Dedonder 1,2,3, Edwin De Petter 1,2,3, Luc Van Wiemeersch 1,2,3, Henri Fredericq 1,2,3, Jan De Greef 1,2,3, Herman Steyaert 1,2,3, Hilde Stevens 1,2,3
PMCID: PMC1056310  PMID: 16665187

Abstract

The fluence-response curves for the effect of two red pulses separated by 24 hours on the germination of Kalanchoe blossfeldiana Poelln. cv Vesuv seeds, incubated on gibberellic acid (GA3) are biphasic for suboptimal concentrations. The response in the low fluence range corresponds with a classical red/far-red reversible phytochrome mediated reaction. GA3 induces an additional response in the very low fluence range, which is also phytochrome mediated. The sensitivity to phytochrome-far-red absorbing form (Pfr), however, is increased about 20,000-fold, so that even far-red fluences become saturating. Both in the very low and low fluence response range, the maximal responses induced by saturating fluences are modulated by the GA3 concentration. GA3 having no direct influence on the phytochrome phototransformations, alters the Pfr requirement and determines the responding seed population fraction in the very low and low fluence range. The effet of GA3 appears to be on the transduction chain of the phytochrome signal.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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