Phytochromes inhibit hypocotyl negative gravitropism by regulating the development of endodermal amyloplasts through phytochrome-interacting factors
Open Access
- 10 January 2011
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences of the United States of America
- Vol. 108 (4), 1729-1734
- https://doi.org/10.1073/pnas.1011066108
Abstract
Phytochromes are red and far-red light photoreceptors that regulate various aspects of plant development. One of the less-understood roles of phytochromes is the inhibition of hypocotyl negative gravitropism, which refers to the loss of hypocotyl gravitropism and resulting random growth direction in red or far-red light. This light response allows seedlings to curve toward blue light after emergence from the soil and enhances seedling establishment in the presence of mulch. Phytochromes inhibit hypocotyl negative gravitropism by inhibiting four phytochrome-interacting factors (PIF1, PIF3, PIF4, PIF5), as shown by hypocotyl agravitropism of dark-grown pif1 pif3 pif4 pif5 quadruple mutants. We show that phytochromes inhibit negative gravitropism by converting starch-filled gravity-sensing endodermal amyloplasts to other plastids with chloroplastic or etioplastic features in red or far-red light, whereas PIFs promote negative gravitropism by inhibiting the conversion of endodermal amyloplasts to etioplasts in the dark. By analyzing transgenic plants expressing PIF1 with an endodermis-specific SCARECROW promoter, we further show that endodermal PIF1 is sufficient to inhibit the conversion of endodermal amyloplasts to etioplasts and hypocotyl negative gravitropism of the pif quadruple mutant in the dark. Although the functions of phytochromes in gravitropism and chloroplast development are normally considered distinct, our results indicate that these two functions are closely related.This publication has 53 references indexed in Scilit:
- Phytochrome functions in Arabidopsis developmentJournal of Experimental Botany, 2009
- Phytochromes promote seedling light responses by inhibiting four negatively-acting phytochrome-interacting factorsProceedings of the National Academy of Sciences of the United States of America, 2009
- PIF3 is a repressor of chloroplast developmentProceedings of the National Academy of Sciences of the United States of America, 2009
- A Role for the TOC Complex in Arabidopsis Root GravitropismPlant Physiology, 2009
- Genome-Wide Analysis of Genes Targeted by PHYTOCHROME INTERACTING FACTOR 3-LIKE5 during Seed Germination in ArabidopsisTHE PLANT CELL ONLINE, 2009
- Multiple Phytochrome-Interacting bHLH Transcription Factors Repress Premature Seedling Photomorphogenesis in DarknessCurrent Biology, 2008
- PHYTOCHROME KINASE SUBSTRATE4 Modulates Phytochrome-Mediated Control of Hypocotyl Growth OrientationPlant Physiology, 2008
- Rapid Synthesis of Auxin via a New Tryptophan-Dependent Pathway Is Required for Shade Avoidance in PlantsCell, 2008
- Canopy shade causes a rapid and transient arrest in leaf development through auxin-induced cytokinin oxidase activityGenes & Development, 2007
- A New CULLIN 1 Mutant Has Altered Responses to Hormones and Light in ArabidopsisPlant Physiology, 2006