Location: Plant Gene Expression CenterTitle: Phytochrome and retrograde signalling pathways coverage to antogonistically regulate a light-induced transcription network Author
|Martin, G - University Of California|
|Leviar, P - University Of California|
|Ludevid, D - University Of California|
|Tepperman, J.m. - University Of California|
|Quail, P.h. - University Of California|
|Monte, E - University Of California|
Submitted to: Nature Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/2/2014
Publication Date: 10/21/2014
Citation: Martin, G., Leviar, P., Ludevid, D., Tepperman, J., Quail, P., Monte, E. 2014. Phytochrome and retrograde signalling pathways coverage to antogonistically regulate a light-induced transcription network. Nature Communications. 7:11431.
Interpretive Summary: This work shows that signals from two pathways (one from the chloroplast to the nucleus (called retrograde signaling), and the other, light signals perceived by the phytochrome (phy) sensory photoreceptors) converge to co-regulate a gene, called GLK1. This gene encodes a transcription factor that in turn is a key regulator of a light-induced transcriptional network central to normal seedling development. Collectively, our data indicate that light at moderate levels acts through the plant’s phy system to induce appropriate seedling development, but at excessive levels, sensed through the chloroplast-localized retrograde signaling system, acts to suppress such development. This provides the seedling with a mechanism to protect itself against photooxidative damage by minimizing exposure to high-intensity sunlight.
Technical Abstract: Plastid-to-nucleus retrograde signals emitted by dysfunctional chloroplasts impact photomorphogenic development, but the molecular link between retrograde and photosensory-receptor signaling has remained undefined. Here, we show that the phytochrome (phy) and retrograde signaling 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 transcription is directly repressed by PIF (PHYTOCHROME-INTERACTING FACTOR)-class bHLH transcription factors in darkness, but light-activated phy 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 retrograde signaling system, acts to suppress such development, thus providing a mechanism for protection against photooxidative damage by minimizing tissue exposure to deleterious radiation.