A dominant mutation inArabidopsis confers resistance to auxin, ethylene and abscisic acid

Wilson, Allison K.; Pickett, F. Bryan; Turner, Jocelyn C.; Estelle, Mark

doi:10.1007/bf00633843

Cited by 428 publications

(307 citation statements)

References 31 publications

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“…For axenic growth of seedlings, seeds were sterilized and stratified at 4°C for several days. Seedlings were grown on Arabidopsis thaliana salts (ATS) medium (Wilson et al, 1990) with 1% sucrose, solidified with 0.8% agar. Plates were oriented vertically in growth chambers with a 16-h/8-h light/dark cycle (22°C/18°C), with light provided by white fluorescent tubes (intensity ;150 mmol m 22 s 21 ).…”

Section: Plant Growth Conditionsmentioning

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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Section: Plant Growth Conditionsmentioning

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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“…The potential auxin efflux component, AtPIN2, allelic to the ethylene-insensitive root1 (EIR1) is an example (Muller et al, 1998). Analogously, axr2 is a dominant mutant that gives resistance to both ethylene and auxin (Wilson et al, 1990). IAA induced ethylene production may be a factor involved in the stimulation of adventitious rooting (Pan et al, 2002).…”

Section: The Plant Hormone Auxinmentioning

confidence: 99%

Auxin Control in the Formation of Adventitious Roots

Pop

Pamfil

Bellini

2011

Not Bot Hort Agrobot Cluj

140

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Adventitious rooting is a complex process and a key step in the vegetative propagation of economically important woody, horticultural and agricultural species, playing an important role in the successful production of elite clones. The formation of adventitious roots is a quantitative genetic trait regulated by both environmental and endogenous factors. Among phytohormones, auxin plays an essential role in regulating roots development and it has been shown to be intimately involved in the process of adventitious rooting. Great progress has been made in elucidating the auxin-induced genes and auxin signaling pathway, especially in auxin response Aux/IAA and Auxin Response Factor gene families. Although some important aspects of adventitious and lateral rooting signaling have been revealed, the intricate signaling network remains poorly understood. This review summarizes some of the current knowledge on the physiological aspects of adventitious root formation and highlights the recent progress made in the identification of putative molecular players involved in the control of adventitious rooting. Despite much has been discovered regarding the effects and regulation of auxins on plant growth since the Darwin experiments, there is much that remains unknown.

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“…Two Arabidopsis mutants selected for resistance t3 auxin at the seedling stage, the dominant mutant AXR.! and the recessive mutant auxl, are both resistant to ethylene (Wilson et al, 1990).…”

Section: Coupling Cytokinin Action To Ethylenementioning

confidence: 99%

Cytokinin Action Is Coupled to Ethylene in Its Effects on the Inhibition of Root and Hypocotyl Elongation in Arabidopsis thaliana Seedlings

1995

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and Ecker, 1990). Some of these features have been utilized in the isolation of mutants with altered responses to ethylene . Ethylene-resistant mutants (ein or etr mutants) were identified by selecting seedlings that fail to express the triple response in the presente of ethylene. Other mutants were identified that pr0duc-d a triple-response phenotype constitutively, i.e. when no ethylene was applied. These mutants have been grouped into two classes, ethylene overproducers (eto) and constitutive triple-response mutants (ctr), distinguished on the basis of whether the phenotype is suppressed by inhibitors Of ethYlene biosynthesis Or action (Guzmán and Eckerr l990). Through epistasis analysis of the mutants, ethylene-response genes have been ordered on an unbranched pathway . Interestingly, ein or etr mutants appear to have very little effect on the normal growth and development of light-grown Arabidopsis seedlings in the absence of supplied ethylene.We have examined the relationship between cytokinin and ethylene responses in Arabidopsis seedlings and have found that ethylene largely mediates a number of responses to exogenous cytokinin, such as the inhibition of root and hypocotyl elongation. Cytokinin stimulates ethylene production, which, in turn, inhibits root and darkgrown hypocotyl elongation. Because of that, the effects of cytokinin on root and hypocotyl elongation can be blocked, in part, by the action of ethylene inhibitors or by ethylene mutants. These results constitute genetic proof of the idea put forth by Lieberman (1979) that cytokinin is coupled to ethylene action in seedlings.Cytokinins have profound effects on seedling development in Arabidopsis thaliana. Benzyladenine (BA) inhibits root elongation in light-or dark-grown seedlings, and in dark-grown seedlings BA inhibits hypocotyl elongation and exaggerates the curvature of apical hooks. The latter are characteristic ethylene responses and, therefore, the possible involvement of ethylene in BA responses was examined in seedlings. It was found that the inhibitory effects of BA on root and hypocotyl elongation were partially blocked by the action of ethylene inhibitors or ethylene-resistant mutations (ein7-7 and ein2-7). Ethylene production was stimulated by submicromolar concentrations of BA and could account, in part, for the inhibition of root and hypocotyl elongation. It was demonstrated further that BA did not affect the sensitivity of seedlings to ethylene. Thus, the effect of cytokinin on root and hypocotyl elongation in Arabidopsis appears to be mediated largely by the production of ethylene. The coupling between cytokinin and ethylene responses is further SUPported by the discovery that the cytokinin-resistant mutant ckrl is resistant to ethylene and is allelic to the ethylene-resistant mutant ein2.The responses of seedlings to developmental and environmental cues have been useful in studying signal transduction pathways in plants. Arabidopsis thaliana seedlings respond to exogenously added or endogenous cytokinins, and in light-grown se...

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A dominant mutation inArabidopsis confers resistance to auxin, ethylene and abscisic acid

Cited by 428 publications

References 31 publications

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

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

Auxin Control in the Formation of Adventitious Roots

Cytokinin Action Is Coupled to Ethylene in Its Effects on the Inhibition of Root and Hypocotyl Elongation in Arabidopsis thaliana Seedlings

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