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Identifizierung und Charakterisierung von Phytochrom A-abhängigen HIR-Reaktionsmodulen

Fachliche Zuordnung Pflanzenphysiologie
Förderung Förderung von 2013 bis 2017
Projektkennung Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 233625604
 
Erstellungsjahr 2017

Zusammenfassung der Projektergebnisse

Phytochromes are red/far-red light receptors in plants that play an important role in regulation of growth and development and the adaptation to the ambient environment. Gene duplication events during evolution of seed plants resulted in small gene families coding for phytochromes in today’s land plants. Phytochrome A (phyA) and B (phyB) are the primary phytochromes in seed plants. The absorption spectra of phyA and phyB are virtually identical and suggest a function as red light receptors. phyB behaves as expected and is activated by red light. In contrast, phyA has an action peak in far-red light, where phytochromes would be expected to be less active than in red light. We have previously shown that the mechanism by which lightactivated phyA is transported into the nucleus contributes to shaping its action spectrum. However, these studies have also shown that additional mechanisms exist that are essential to obtain the full red→far-red shift of the phyA action peak. This shift is important for induction of germination and seedling establishment in strong canopy shade. Here, we investigated potential mechanism that could shift the peak of the phyA action spectrum to far-red light. The key finding is that phytochrome dimers consisting of two active phytochromes (homodimers) and such consisting of one active and one inactive phytochrome (heterodimers) behave differently and that the different behaviour could account for the different action spectra of phyA and phyB. We measured different properties of phyA, such as degradation and dark reversion, under light conditions generating predominantly homo- or heterodimers. These data are currently being used to test a mathematical model to explain the shift of the phyA action peak from red to far-red light.

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