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Nat Commun. 2016 May 6;7:11431. doi: 10.1038/ncomms11431.

Phytochrome and retrograde signalling pathways converge to antagonistically regulate a light-induced transcriptional network.

Author information

1
Department of Molecular Genetics, Center for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Barcelona 08193, Spain.
2
Department of Bioengineering, IQS School of Engineering, Barcelona 08017, Spain.
3
Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA.
4
Plant Gene Expression Center, Agriculture Research Service (ARS), US Department of Agriculture (USDA), Albany, California 94710, USA.

Abstract

Plastid-to-nucleus retrograde signals emitted by dysfunctional chloroplasts impact photomorphogenic development, but the molecular link between retrograde- and photosensory-receptor signalling has remained unclear. Here, we show that the phytochrome and retrograde signalling (RS) pathways converge antagonistically to regulate the expression of the nuclear-encoded transcription factor GLK1, a key regulator of a light-induced transcriptional network central to photomorphogenesis. GLK1 gene transcription is directly repressed by PHYTOCHROME-INTERACTING FACTOR (PIF)-class bHLH transcription factors in darkness, but light-activated phytochrome reverses this activity, thereby inducing expression. Conversely, we show that retrograde signals repress this induction by a mechanism independent of PIF mediation. Collectively, our data indicate that light at moderate levels acts through the plant's nuclear-localized sensory-photoreceptor system to induce appropriate photomorphogenic development, but at excessive levels, sensed through the separate plastid-localized RS system, acts to suppress such development, thus providing a mechanism for protection against photo-oxidative damage by minimizing the tissue exposure to deleterious radiation.

PMID:
27150909
PMCID:
PMC4859062
DOI:
10.1038/ncomms11431
[Indexed for MEDLINE]
Free PMC Article

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