Shade Promotes Phototropism through Phytochrome B-Controlled Auxin Production.

Details

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State: Public
Version: Author's accepted manuscript
Serval ID
serval:BIB_4D2BFF974130
Type
Article: article from journal or magazin.
Collection
Publications
Title
Shade Promotes Phototropism through Phytochrome B-Controlled Auxin Production.
Journal
Current biology
Author(s)
Goyal A., Karayekov E., Galvão V.C., Ren H., Casal J.J., Fankhauser C.
ISSN
1879-0445 (Electronic)
ISSN-L
0960-9822
Publication state
Published
Issued date
19/12/2016
Peer-reviewed
Oui
Volume
26
Number
24
Pages
3280-3287
Language
english
Notes
Publication types: Journal Article
Publication Status: ppublish
Abstract
Phototropism is an asymmetric growth response enabling plants to optimally position their organs. In flowering plants, the phototropin (phot) blue light receptors are essential to detect light gradients. In etiolated seedlings, the phototropic response is enhanced by the red/far-red (R/FR)-sensing phytochromes (phy) with a predominant function of phyA. In this study, we analyzed the influence of the phytochromes on phototropism in green (de-etiolated) Arabidopsis seedlings. Our experiments in the laboratory and outdoors revealed that, in open environments (high R/FR ratio), phyB inhibits phototropism. In contrast, under foliar shade, where access to direct sunlight becomes important, the phototropic response was strong. phyB modulates phototropism, depending on the R/FR ratio, by controlling the activity of three basic-helix-loop-helix (bHLH) transcription factors of the PHYTOCHROME INTERACTING FACTORs (PIFs) family. Promotion of phototropism depends on PIF-mediated induction of several members of the YUCCA gene family, leading to auxin production in the cotyledons. Our study identifies PIFs and YUCCAs as novel molecular players promoting phototropism in photoautotrophic, but not etiolated, seedlings. Moreover, our findings reveal fundamental differences in the phytochrome-phototropism crosstalk in etiolated versus green seedlings. We propose that in natural conditions where the light environment is not homogeneous, the uncovered phytochrome-phototropin co-action is important for plants to adapt their growth strategy to optimize photosynthetic light capture.

Keywords
Arabidopsis/physiology, Arabidopsis Proteins/genetics, Arabidopsis Proteins/metabolism, Gene Expression Regulation, Plant/physiology, Indoleacetic Acids/metabolism, Light, Phototropism/physiology, Phytochrome B/physiology, Seedlings/physiology, Arabidopsis thaliana, PHYTOCHROME-INTERACTING FACTORs, YUCCAs, photoreceptor crosstalk, phototropin 1, phototropism, phytochrome B, shade avoidance
Pubmed
Web of science
Create date
06/12/2016 19:51
Last modification date
20/08/2019 15:01
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