Strigolactone signaling is required for auxin-dependent stimulation of secondary growth in plants

Agustí, Javier; Herold, Silvia; Schwarz, Martina; Sánchez, Pablo; Ljung, Karin; Dun, Elizabeth A.; Brewer, Philip B.; Beveridge, Christine A.; Sieberer, Tobias; Sehr, Eva Maria; Greb, Thomas

doi:10.1073/pnas.1111902108

Cited by 353 publications

(277 citation statements)

References 58 publications

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“…In stem cuttings, root primordia typically emerge from cambial cell division activity, a stem cell-like cell layer that is required for vascular bundle formation and in addition, secondary growth. Whereas strigolactones may reduce the cambial activity required for adventitious root initiation, they conversely stimulate secondary growth by promoting cambial cell divisions independent or downstream from strigolactone-controlled auxin accumulation (Agusti et al 2011). These apparently opposing actions in cambial regulation suggest that the role of strigolactones depends on the physiological status of the plant, whereby wound-induced adventitious rooting on cuttings or light-induced Arabidopsis hypocotyls cambium activity is suppressed and stimulated in stems and roots of maturing plants.…”

Section: Strigolactones Inhibit Adventitious Root Formationmentioning

confidence: 99%

Strigolactones fine-tune the root system

Rasmussen

Depuydt

Goormachtig

et al. 2013

Planta

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Strigolactones were originally discovered to be involved in parasitic weed germination, in mycorrhizal association and in the control of shoot architecture. Despite their clear role in rhizosphere signaling, comparatively less attention has been given to the belowground function of strigolactones on plant development. However, research has revealed that strigolactones play a key role in the regulation of the root system including adventitious roots, primary root length, lateral roots, root hairs and nodulation. Here, we review the recent progress regarding strigolactone regulation of the root system and the antagonism and interplay with other hormones

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Section: Strigolactones Inhibit Adventitious Root Formationmentioning

confidence: 99%

Strigolactones fine-tune the root system

Rasmussen

Depuydt

Goormachtig

et al. 2013

Planta

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“…Interestingly, max2 and SL biosynthetic mutants also have reduced interfascicular cambium compared with Col-0, and treatment with SL can promote interfascicular cambium development (Agusti et al, 2011). It is thus very difficult to assess the ability of the SMXL variants to restore the smxl678 max2 phenotype toward the max2 phenotype.…”

Section: The Ear Motif Contributes To But Is Not Essential For Smxl7mentioning

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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“…In 2008, these lines of evidence were brought together to show that strigolactones were endogenous plant hormones responsible for controlling shoot architecture (Gomez-Roldan et al 2008;Umehara et al 2008). Since this major step forward was made, strigolactones have been implicated in numerous other processes, including leaf senescence (Snowden et al 2005;Yamada et al 2014), adventitious rooting (Rasmussen et al 2012), secondary thickening (Agusti et al 2011), and regulation of root architecture under changing nutrient conditions (Ruyter-Spira et al 2011;Mayzlish-Gati et al 2012; reviewed by Al-Babili and Bouwmeester 2015; Waters et al 2017).…”

Section: Karrikins Are Structurally Related To Strigolactonesmentioning

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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Strigolactone signaling is required for auxin-dependent stimulation of secondary growth in plants

Abstract: www.pnas.org

Cited by 353 publications

References 58 publications

Strigolactones fine-tune the root system

Strigolactones fine-tune the root system

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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