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New Phytol. 2016 Jul;211(2):584-98. doi: 10.1111/nph.13941. Epub 2016 Mar 30.

Characterization of photomorphogenic responses and signaling cascades controlled by phytochrome-A expressed in different tissues.

Author information

1
Faculty of Biology, Institute of Molecular Plant Physiology, University of Freiburg, Schänzlestrasse 1, D-79104, Freiburg, Germany.
2
Institute of Plant Biology, Biological Research Centre, Temesvári krt.62, Szeged, H-6726, Hungary.
3
Institute of Biophysics, Biological Research Centre, Temesvári krt.62, Szeged, H-6726, Hungary.
4
BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, 79104, Germany.
5
Institute of Molecular Plant Science, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3JH, UK.

Abstract

The photoreceptor phytochrome A acts as a light-dependent molecular switch and regulates responses initiated by very low fluences of light (VLFR) and high fluences (HIR) of far-red light. PhyA is expressed ubiquitously, but how phyA signaling is orchestrated to regulate photomorphogenesis is poorly understood. To address this issue, we generated transgenic Arabidopsis thaliana phyA-201 mutant lines expressing the biologically active phyA-YFP photoreceptor in different tissues, and analyzed the expression of several reporter genes, including ProHY5:HY5-GFP and Pro35S:CFP-PIF1, and various FR-HIR-dependent physiological responses. We show that phyA action in one tissue is critical and sufficient to regulate flowering time and root growth; control of cotyledon and hypocotyl growth requires simultaneous phyA activity in different tissues; and changes detected in the expression of reporters are not restricted to phyA-containing cells. We conclude that FR-HIR-controlled morphogenesis in Arabidopsis is mediated partly by tissue-specific and partly by intercellular signaling initiated by phyA. Intercellular signaling is critical for many FR-HIR induced responses, yet it appears that phyA modulates the abundance and activity of key regulatory transcription factors in a tissue-autonomous fashion.

KEYWORDS:

Arabidopsis thaliana; photomorphogenesis; phytochrome A; signaling; tissue/cell specificity; transcription

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PMID:
27027866
DOI:
10.1111/nph.13941
[Indexed for MEDLINE]
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