Effect of Light on Root Hair Formation in Arabidopsis thaliana Phytochrome-Deficient Mutants

(J.H.).In plants, the multistep phosphorelay (MSP) pathway mediates a range of regulatory processes, including those activated by cytokinins. The cross talk between cytokinin response and light has been known for a long time. However, the molecular mechanism underlying the interaction between light and cytokinin signaling remains elusive. In the screen for upstream regulators we identified a LONG PALE HYPOCOTYL (LPH) gene whose activity is indispensable for spatiotemporally correct expression of CYTOKININ INDEPENDENT1 (CKI1), encoding the constitutively active sensor His kinase that activates MSP signaling. lph is a new allele of HEME OXYGENASE1 (HY1) that encodes the key protein in the biosynthesis of phytochromobilin, a cofactor of photoconvertible phytochromes. Our analysis confirmed the light-dependent regulation of the CKI1 expression pattern. We show that CKI1 expression is under the control of phytochrome A (phyA), functioning as a dual (both positive and negative) regulator of CKI1 expression, presumably via the phyA-regulated transcription factors (TF) PHYTOCHROME INTERACTING FACTOR3 and CIRCADIAN CLOCK ASSOCIATED1. Changes in CKI1 expression observed in lph/hy1-7 and phy mutants correlate with misregulation of MSP signaling, changed cytokinin sensitivity, and developmental aberrations that were previously shown to be associated with cytokinin and/or CKI1 action. Besides that, we demonstrate a novel role of phyA-dependent CKI1 expression in the hypocotyl elongation and hook development during skotomorphogenesis. Based on these results, we propose that the light-dependent regulation of CKI1 provides a plausible mechanistic link underlying the well-known interaction between light-and cytokinin-controlled plant development.

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“…4A). This is also in line with the previously documented role of phytochromes in root hair formation (De Simone et al, 2000).…”

Section: Light-regulated Cki1 Controls Root Growthsupporting

confidence: 92%

Light Controls Cytokinin Signaling via Transcriptional Regulation of Constitutively Active Sensor Histidine Kinase CKI1

et al. 2017

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“…Mutations in either the PHYTOCHROME A (PHYA: At1g09570) or PHYB (At2g18790) genes affect the length of root hairs grown in the light, showing that phytochrome signaling can influence the amount of tip growth that takes place (Reed et al, 1993;DeSimone et al, 2000).…”

Section: Molecular Genetics Of Root Hair Formationmentioning

confidence: 99%

Root Hairs

Grierson

Nielsen

Ketelaarc

et al. 2014

The Arabidopsis Book

182

220

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Roots hairs are cylindrical extensions of root epidermal cells that are important for acquisition of nutrients, microbe interactions, and plant anchorage. The molecular mechanisms involved in the specification, differentiation, and physiology of root hairs in Arabidopsis are reviewed here. Root hair specification in Arabidopsis is determined by position-dependent signaling and molecular feedback loops causing differential accumulation of a WD-bHLH-Myb transcriptional complex. The initiation of root hairs is dependent on the RHD6 bHLH gene family and auxin to define the site of outgrowth. Root hair elongation relies on polarized cell expansion at the growing tip, which involves multiple integrated processes including cell secretion, endomembrane trafficking, cytoskeletal organization, and cell wall modifications. The study of root hair biology in Arabidopsis has provided a model cell type for insights into many aspects of plant development and cell biology.

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“…52 Moreover, light was shown to positively regulate root-hair formation in Arabidopsis. 53 SLs are suggested to be associated with both inhibition of lateral root initiation and root hair elongation. 40 Therefore, it might be that SLs are mediators of root-light responses.…”

Section: Strigolactones Affect Shoot Developmentmentioning

confidence: 99%

Strigolactones as mediators of plant growth responses to environmental conditions

Koltai¹,

Kapulnik²

2011

psb

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Effect of Light on Root Hair Formation in Arabidopsis thaliana Phytochrome-Deficient Mutants

Cited by 46 publications

References 43 publications

Light Controls Cytokinin Signaling via Transcriptional Regulation of Constitutively Active Sensor Histidine Kinase CKI1

Light Controls Cytokinin Signaling via Transcriptional Regulation of Constitutively Active Sensor Histidine Kinase CKI1

Root Hairs

Strigolactones as mediators of plant growth responses to environmental conditions

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