Interdependent Nutrient Availability and Steroid Hormone Signals Facilitate Root Growth Plasticity

Singh, Amar Pal; Fridman, Yulia; Holland, Neta; Ackerman-Lavert, M.; Zananiri, Rani; Jaillais, Yvon; Henn, Arnon; Savaldi-Goldstein, Sigal

doi:10.1016/j.devcel.2018.06.002

Cited by 78 publications

(79 citation statements)

References 58 publications

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“…We, and others, have previously shown that several aspects of the root growth arrest under –Pi conditions are dependent on Fe (Svistoonoff et al ., ; Ward et al ., ; Muller et al ., ; Dong et al ., ; Gutiérrez‐Alanís et al ., ; Singh et al ., ; Wang et al ., ), but the exact relationships between –Pi and Fe were unclear. Here, we focused our work on STOP1 signaling and succeeded in dissociating the effect of –Pi itself from the role of Fe in STOP1 signaling.…”

Section: Discussionmentioning

confidence: 99%

“…A higher level of regulation coupling LPR1 with brassinosteroid (BR) signaling pathways has recently been unveiled. In particular, the root growth of seedlings with the constitutively active bzr1‐D mutation ( BZR1 for BRASSINAZOLE RESISTANT1 ) is unrepressed in –Pi and expression of LPR1 is reduced (Singh et al ., , ). In addition, in the wild type (WT), Fe enhances the accumulation of the BR‐signaling inhibitor BKI1 (BRASSINSOSTEROID KINASE INHIBITOR1), thereby closing a feedback regulatory loop between LPR1 activity and BR signaling.…”

Section: Introductionmentioning

confidence: 99%

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Under phosphate starvation conditions, Fe and Al trigger accumulation of the transcription factor STOP1 in the nucleus of Arabidopsis root cells

et al. 2019

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Summary Low‐phosphate (Pi) conditions are known to repress primary root growth of Arabidopsis at low pH and in an Fe‐dependent manner. This growth arrest requires accumulation of the transcription factor STOP1 in the nucleus, where it activates the transcription of the malate transporter gene ALMT1; exuded malate is suspected to interact with extracellular Fe to inhibit root growth. In addition, ALS3 – an ABC‐like transporter identified for its role in tolerance to toxic Al – represses nuclear accumulation of STOP1 and the expression of ALMT1. Until now it was unclear whether Pi deficiency itself or Fe activates the accumulation of STOP1 in the nucleus. Here, by using different growth media to dissociate the effects of Fe from Pi deficiency itself, we demonstrate that Fe is sufficient to trigger the accumulation of STOP1 in the nucleus, which, in turn, activates the expression of ALMT1. We also show that a low pH is necessary to stimulate the Fe‐dependent accumulation of nuclear STOP1. Furthermore, pharmacological experiments indicate that Fe inhibits proteasomal degradation of STOP1. We also show that Al acts like Fe for nuclear accumulation of STOP1 and ALMT1 expression, and that the overaccumulation of STOP1 in the nucleus of the als3 mutant grown in low‐Pi conditions could be abolished by Fe deficiency. Altogether, our results indicate that, under low‐Pi conditions, Fe2/3+ and Al3+ act similarly to increase the stability of STOP1 and its accumulation in the nucleus where it activates the expression of ALMT1.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Under phosphate starvation conditions, Fe and Al trigger accumulation of the transcription factor STOP1 in the nucleus of Arabidopsis root cells

et al. 2019

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“…Upon Fe in the root tip, the BRASSINOSTEROID KINASE INHIBITOR 1 (BKI1) accumulates and inhibits downstream BRASSINAZOLE RESISTANT1 (BZR1) activity. BZR1 in turn is part of a feedback loop controlling LPR1 regulation and Fe accumulation (Singh et al, 2018…”

Section: Phosphate-starvation-regulated Root Growth Is Iron Dependentmentioning

confidence: 99%

Tackling Plant Phosphate Starvation by the Roots

2019

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Plant responses to phosphate deprivation encompass a wide range of strategies, varying from altering root system architecture, entering symbiotic interactions to excreting root exudates for phosphorous release, and recycling of internal phosphate. These processes are tightly controlled by a complex network of proteins that are specifically upregulated upon phosphate starvation. Although the different effects of phosphate starvation have been intensely studied, the full extent of its contribution to altered root system architecture remains unclear. In this review, we focus on the effect of phosphate starvation on the developmental processes that shape the plant root system and their underlying molecular pathways.

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“…Similar scenarios regarding the interplay between ion and BRs have also been seen in iron ions. A recent report found that low iron availability in soil accelerates Arabidopsis root growth by activating BR signaling, whereas high iron concentration shows an opposite effect [156]. Altered hormone signaling intensity, in turn, modulates iron accumulation in the root elongation and differentiation zones, constituting a regulatory feedback loop between BR and iron [156].…”

Section: Minerals and Ionsmentioning

confidence: 99%

Molecular Mechanisms of Brassinosteroid-Mediated Responses to Changing Environments in Arabidopsis

2020

IJMS

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Plant adaptations to changing environments rely on integrating external stimuli into internal responses. Brassinosteroids (BRs), a group of growth-promoting phytohormones, have been reported to act as signal molecules mediating these processes. BRs are perceived by cell surface receptor complex including receptor BRI1 and coreceptor BAK1, which subsequently triggers a signaling cascade that leads to inhibition of BIN2 and activation of BES1/BZR1 transcription factors. BES1/BZR1 can directly regulate the expression of thousands of downstream responsive genes. Recent studies in the model plant Arabidopsis demonstrated that BR biosynthesis and signal transduction, especially the regulatory components BIN2 and BES1/BZR1, are finely tuned by various environmental cues. Here, we summarize these research updates and give a comprehensive review of how BR biosynthesis and signaling are modulated by changing environments and how these changes regulate plant adaptive growth or stress tolerance.Int. J. Mol. Sci. 2020, 21, 2737 3 of 20 BR signal cascade by phosphorylating BR SIGNALING KINASE 1 (BSK1) and CDG1, two receptor-like cytoplasmic kinases (RLCKs) that are anchored to the cell membrane [59,60]. Activated CDG1 can subsequently phosphorylate and activate a protein phosphatase BSU1, which then dephosphorylates and inactivates a GSK3 kinase BRASSINOSTEROID INSENSITIVE 2 (BIN2) [60][61][62]. BIN2 is a negative regulator in the BR signaling pathway because it phosphorylates and destabilizes two well-characterized downstream transcription factors, BRI1-EMS-SUPPRESSOR 1 (BES1) and BRSSINAZOLE-RESISTANT 1 (BZR1), and presumably other four members of their entire subfamily [63][64][65][66][67]. BR-induced BIN2 inactivation allows the accumulation of nonphosphorylated BES1 and BZR1 in the nucleus, thereby promoting expression of thousands of their target genes [62,68]. The intensity of BR signaling can be controlled at multiple levels (Figure 2). At the receptor level, the function of BRI1 can be post-translationally regulated by PUB12/13-directed ubiquitination, PP2A-mediated dephosphorylation, BKI1-mediated kinase inhibition, and BIK1-and BIR3-mediated competition for the coreceptor BAK1 [69][70][71][72][73]. At the BIN2 level, it has been reported that BIN2 is regulated by OCTOPUSor POLAR-mediated membrane sequestration, HDA6-mediated deacetylation, KIB1-mediated ubiquitination, TTL-enhanced interaction with BSU1, ABI1/2-mediated dephosphorylation, and ROS (reactive oxygen species)-mediated oxidation [74][75][76][77][78][79][80]. At the transcription level, it has been reported that PP2A phosphatases can promote BR signaling by dephosphorylating BES1 and BZR1, whereas 14-3-3 and BRZ-SENSITIVE-SHORT HYPOCOTYL1 (BSS1) negatively regulate BR signaling by inhibiting the translocation of BES1 and BZR1 from the cytosol to the nucleus [81][82][83]. Besides, protein degradation of BES1 and/or BZR1 has been reported to be regulated by many factors, including an F-box protein MORE AXILLARY GROWTH LOCUS2 (MAX2), ubiquitin E3 ligases suc...

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Interdependent Nutrient Availability and Steroid Hormone Signals Facilitate Root Growth Plasticity

Cited by 78 publications

References 58 publications

Under phosphate starvation conditions, Fe and Al trigger accumulation of the transcription factor STOP1 in the nucleus of Arabidopsis root cells

Under phosphate starvation conditions, Fe and Al trigger accumulation of the transcription factor STOP1 in the nucleus of Arabidopsis root cells

Tackling Plant Phosphate Starvation by the Roots

Molecular Mechanisms of Brassinosteroid-Mediated Responses to Changing Environments in Arabidopsis

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