<i>SUPPRESSOR OF MORE AXILLARY GROWTH2 1</i> Controls Seed Germination and Seedling Development in Arabidopsis

Stanga, John P.; Smith, Steven M.; Briggs, Winslow R.; Nelson, David C.

doi:10.1104/pp.113.221259

Cited by 237 publications

(261 citation statements)

References 67 publications

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“…However, nothing is currently known about the subsequent effects of D53 degradation and how this protein acts to suppress SL signaling. D53 belongs to a small family of proteins [SMAX1-like (SMXL)] that show some homology with class I CIp ATPase enzymes (Stanga et al, 2013). The presence of potential ethyleneresponsive element binding factor-associated amphiphilic repression (EAR) motifs in D53 and its ability to interact with topless-related (TPR) proteins, which are known transcriptional corepressors, suggest that a D53-TPR complex could repress the transcription of downstream targets (Bennett and Leyser, 2014;Jiang et al, 2013;Smith and Li, 2014), but this has not yet been demonstrated.…”

Section: Sl Signaling: the Role Of Ups-dependent Protein Degradationmentioning

confidence: 99%

Strigolactone biosynthesis and signaling in plant development

et al. 2015

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Strigolactones (SLs), first identified for their role in parasitic and symbiotic interactions in the rhizosphere, constitute the most recently discovered group of plant hormones. They are best known for their role in shoot branching but, more recently, roles for SLs in other aspects of plant development have emerged. In the last five years, insights into the SL biosynthetic pathway have also been revealed and several key components of the SL signaling pathway have been identified. Here, and in the accompanying poster, we summarize our current understanding of the SL pathway and discuss how this pathway regulates plant development.

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Section: Sl Signaling: the Role Of Ups-dependent Protein Degradationmentioning

confidence: 99%

Strigolactone biosynthesis and signaling in plant development

et al. 2015

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“…The principle proteolytic targets of SL signaling appear to be a clade of proteins in the SMAX1-LIKE (SMXL) family, typified by SMXL7 in Arabidopsis thaliana and D53 in rice (Oryza sativa) (Jiang et al, 2013;Zhou et al, 2013;Soundappan et al, 2015;Wang et al, 2015). SMXL proteins are weakly homologous to HEAT SHOCK PROTEIN101 ClpB chaperonins and are named for the founding member, SUPPRESSOR OF MAX2 1 (SMAX1) (Stanga et al, 2013). SMAX1 is also a probable target of SCF MAX2 , although in this case in response to signaling mediated by the KAI2 receptor protein, itself a close relative of D14, for which the endogenous ligand is currently unknown Stanga et al, 2013;Soundappan et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

“…SMXL proteins are weakly homologous to HEAT SHOCK PROTEIN101 ClpB chaperonins and are named for the founding member, SUPPRESSOR OF MAX2 1 (SMAX1) (Stanga et al, 2013). SMAX1 is also a probable target of SCF MAX2 , although in this case in response to signaling mediated by the KAI2 receptor protein, itself a close relative of D14, for which the endogenous ligand is currently unknown Stanga et al, 2013;Soundappan et al, 2015). In Arabidopsis, SMXL7 is rapidly degraded in response to treatment with rac-GR24 in a D14-and MAX2-dependent manner (Soundappan et al, 2015;Wang et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

SMAX1-LIKE7 signals from the nucleus to regulate shoot development in Arabidopsis via partially EAR motif-independent mechanisms

et al. 2016

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Strigolactones (SLs) are hormonal signals that regulate multiple aspects of shoot architecture, including shoot branching. Like many plant hormonal signaling systems, SLs act by promoting ubiquitination of target proteins and their subsequent proteasome-mediated degradation. Recently, SMXL6, SMXL7, and SMXL8, members of the SMAX1-LIKE (SMXL) family of chaperonin-like proteins, have been identified as proteolytic targets of SL signaling in Arabidopsis thaliana. However, the mechanisms by which these proteins regulate downstream events remain largely unclear. Here, we show that SMXL7 functions in the nucleus, as does the SL receptor, DWARF14 (D14). We show that nucleus-localized D14 can physically interact with both SMXL7 and the MAX2 F-box protein in a SL-dependent manner and that disruption of specific conserved domains in SMXL7 affects its localization, SL-induced degradation, and activity. By expressing and overexpressing these SMXL7 protein variants, we show that shoot tissues are broadly sensitive to SMXL7 activity, but degradation normally buffers the effect of increasing SMXL7 expression. SMXL7 contains a well-conserved EAR (ETHYLENE-RESPONSE FACTOR Amphiphilic Repression) motif, which contributes to, but is not essential for, SMXL7 functionality. Intriguingly, different developmental processes show differential sensitivity to the loss of the EAR motif, raising the possibility that there may be several distinct mechanisms at play downstream of SMXL7. INTRODUCTIONShoot system architectural characteristics strongly influence the productivity of many crop species, and architectural traits have been selected in both historical and contemporary breeding schemes. Understanding the mechanisms that regulate shoot architecture, and its environmental responsiveness, is therefore an important goal for plant research. It is well established that long-distance hormonal signals, including auxin, cytokinin, and strigolactone (SL), are key regulators of shoot architecture and allow communication both within the shoot system and between the shoot and root . For instance, cytokinin produced in the root system in response to the availability of nitrate ions is systemically transported to the shoot, where it promotes branching (Kiba et al., 2011; Müller et al., 2015). Similarly, root-derived SL plays a key role in negatively regulating branching in response to low phosphate availability in the rhizosphere (Kohlen et al., 2011). However, our understanding of the molecular mechanisms that act downstream of these hormones to alter developmental processes in the shoot is currently limited. This is particularly true of SLs. Analysis of the phenotypes of SL biosynthesis and signaling mutants has revealed roles for SLs in the regulation of shoot branching, branching angle, plant height, stem thickness, and leaf blade elongation . The role of SLs in regulating shoot branching has been intensively studied, resulting in two contrasting, nonexclusive models for their mode of action. In the first, SLs are proposed to act locally in axill...

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“…A suppressor screen for the karrikin-related max2 phenotypes relating to seed germination and seedling growth identified SUPPRESSOR OF MAX2 1 (SMAX1) (Stanga et al 2013). Arabidopsis seedlings deficient in SMAX1 and, to a lesser extent its close paralogue SMAX1-LIKE 2 (SMXL2), resemble wild type seedlings treated with karrikins -i.e.…”

Section: : the Smxl Familymentioning

confidence: 99%

From little things big things grow: karrikins and new directions in plant development

Waters¹

2017

Functional Plant Biol.

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Abstract. Karrikins are a family of compounds generated via the incomplete combustion of plant matter. Since their discovery as seed germination stimulants in 2004, a great deal has been learned about the chemistry and the biological mode of action of karrikins. Much interest and progress have stemmed from the structural similarity of karrikins to that of strigolactones -the shoot branching hormone. This review will provide a historical account of some of the more significant discoveries in this area of plant biology. It will discuss how the study of these abiotic signalling molecules, combined with advances in our understanding of strigolactones, has led us towards the discovery of new mechanisms that regulate plant growth and development.

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SUPPRESSOR OF MORE AXILLARY GROWTH2 1 Controls Seed Germination and Seedling Development in Arabidopsis

Cited by 237 publications

References 67 publications

Strigolactone biosynthesis and signaling in plant development

Strigolactone biosynthesis and signaling in plant development

SMAX1-LIKE7 signals from the nucleus to regulate shoot development in Arabidopsis via partially EAR motif-independent mechanisms

From little things big things grow: karrikins and new directions in plant development

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