Brassinosteroid control of shoot gravitropism interacts with ethylene and depends on auxin signaling components

Auxin plays a key role across all land plants in growth and developmental processes. Although auxin signaling function has diverged and expanded, differences in the molecular functions of signaling components have largely been characterized in Arabidopsis thaliana. Here, we used the Auxin Response Circuit recapitulated in Saccharomyces cerevisiae (ARCSc) system to functionally annotate maize auxin signaling components, focusing on genes expressed during development of ear and tassel inflorescences. All 16 maize Auxin (Aux)/Indole-3-Acetic Acid (IAA) repressor proteins are degraded in response to auxin, with rates that depended on both receptor and repressor identity. When fused to the maize TOPLESS (TPL) homolog RAMOSA1 ENHANCER LOCUS2 (REL2), maize Aux/IAAs were able to repress AUXIN RESPONSE FACTOR (ARF) transcriptional activity. A complete auxin response circuit comprised of all maize components, including ZmAFB2/3 b1 maize AUXIN SIGNALING F-BOX (AFB) receptor, was found to be fully functional. The ZmAFB2/3 b1 auxin receptor was found to be more sensitive to hormone than AtAFB2 and allowed for rapid circuit activation upon auxin addition. These results validate the conserved role of predicted auxin response genes in maize, as well as provide evidence that a synthetic approach can facilitate broader comparative studies across the wide range of species with sequenced genomes.

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Brassinosteroids Regulate the Differential Growth of Arabidopsis Hypocotyls through Auxin Signaling Components IAA19 and ARF7

Molecular Plant ◽

10.1093/mp/sss123 ◽

2013 ◽

Vol 6 (3) ◽

pp. 887-904 ◽

Cited By ~ 36

Author(s):

Xiao-Yi Zhou ◽

Li Song ◽

Hong-Wei Xue

Keyword(s):

Auxin Signaling ◽

Differential Growth ◽

Signaling Components

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Auxin-induced expression divergence between Arabidopsis species likely originates within the TIR1/AFB-AUX/IAA-ARF module

10.1101/038422 ◽

2016 ◽

Author(s):

Jana Trenner ◽

Yvonne Poeschl ◽

Jan Grau ◽

Andreas Gogol-Döring ◽

Marcel Quint ◽

...

Keyword(s):

Gene Expression ◽

Motif Discovery ◽

Natural Variation ◽

De Novo ◽

Gene Clusters ◽

Auxin Signaling ◽

Expression Divergence ◽

Sources Of Variation ◽

Species Comparisons ◽

Signaling Components

HighlightTIR1/AFB, AUX/IAA, and ARF proteins show interspecies expression variation correlating with variation in downstream responses which indicates a source for natural variation within this conserved signaling module.AbstractAuxin is an essential regulator of plant growth and development and auxin signaling components are conserved among land plants. Yet, a remarkable degree of natural variation in physiological and transcriptional auxin responses has been described among Arabidopsis thaliana accessions. As intra-species comparisons offer only limited genetic variation, we here inspect the variation of auxin responses between A. thaliana and A. lyrata. This approach allowed the identification of conserved auxin response genes including novel genes with potential relevance for auxin biology. Furthermore, promoter divergences were analyzed for putative sources of variation. De novo motif discovery identified novel and variants of known elements with potential relevance for auxin responses, emphasizing the complex, and yet elusive, code of element combinations accounting for the diversity in transcriptional auxin responses. Furthermore, network analysis revealed correlations of inter-species differences in the expression of AUX/IAA gene clusters and classic auxin-related genes. We conclude that variation in general transcriptional and physiological auxin responses may originate substantially from functional or transcriptional variations in the TIR1/AFB, AUX/IAA, and ARF signaling network. In that respect, AUX/IAA gene expression divergence potentially reflects differences in the manner in which different species transduce identical auxin signals into gene expression responses.

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Spatial specificity of auxin responses coordinates wood formation

10.1101/142885 ◽

2017 ◽

Author(s):

Klaus Brackmann ◽

Virginie Jouannet ◽

Jiyan Qi ◽

Theresa Schlamp ◽

Karin Grünwald ◽

...

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Spatial Organization ◽

Wood Formation ◽

Auxin Signaling ◽

Cambium Activity ◽

Plant Stem ◽

Cell Niche ◽

Spatial Specificity ◽

Signaling Components

AbstractSpatial organization of signaling events of the phytohormone auxin is fundamental for maintaining a dynamic transition from plant stem cells to differentiated descendants. The cambium, the stem cell niche mediating wood formation, fundamentally depends on auxin signaling but its exact role and spatial organization is obscure. Here, we show that, while auxin signaling levels increase in differentiating cambium descendants, a moderate level of signaling in cambial stem cells is essential for cambium activity. We identify the auxin-dependent transcription factor ARF5/MONOPTEROS to cell-autonomously restrict the number of stem cells by attenuating the activity of the stem cell promoting WOX4 gene. In contrast, ARF3 and ARF4 function as cambium activators in a redundant fashion from outside of WOX4-expressing cells. Our results reveal an influence of auxin signaling on distinct cambium features by specific signaling components and allow the conceptual integration of plant stem cell systems with distinct anatomies.

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Phototropin-mediated perception of light direction in leaves regulates blade flattening

Plant Physiology ◽

10.1093/plphys/kiab410 ◽

2021 ◽

Author(s):

Martina Legris ◽

Bogna Maria Szarzynska-Erden ◽

Martine Trevisan ◽

Laure Allenbach Petrolati ◽

Christian Fankhauser

Keyword(s):

Leaf Development ◽

Light Response ◽

Auxin Signaling ◽

Kinase Substrate ◽

Key Aspects ◽

Light Capture ◽

Signaling Components ◽

Curled Leaves

Abstract One conserved feature among angiosperms is the development of flat thin leaves. This developmental pattern optimizes light capture and gas exchange. The blue light (BL) receptors phototropins are required for leaf flattening, with the null phot1phot2 mutant showing curled leaves in Arabidopsis (Arabidopsis thaliana). However, key aspects of their function in leaf development remain unknown. Here, we performed a detailed spatiotemporal characterization of phototropin function in Arabidopsis leaves. We found that phototropins perceive light direction in the blade, and, similar to their role in hypocotyls, they control the spatial pattern of auxin signaling, possibly modulating auxin transport, to ultimately regulate cell expansion. Phototropin signaling components in the leaf partially differ from hypocotyls. Moreover, the light response on the upper and lower sides of the leaf blade suggests a partially distinct requirement of phototropin signaling components on each side. In particular, NON PHOTOTROPIC HYPOCOTYL 3 showed an adaxial-specific function. In addition, we show a prominent role of PHYTOCHROME KINASE SUBSTRATE 3 in leaf flattening. Among auxin transporters, PIN-FORMED 3,4,7 and AUXIN RESISTANT 1 (AUX1)/LIKE AUXIN RESISTANT 1 (LAX1) are required for the response while ABCB19 has a regulatory role. Overall, our results show that directional BL perception by phototropins is a key aspect of leaf development, integrating endogenous and exogenous signals.

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SCFTIR1/AFB Auxin Signaling for Bending Termination during Shoot Gravitropism

PLANT PHYSIOLOGY ◽

10.1104/pp.20.00212 ◽

2020 ◽

Vol 183 (1) ◽

pp. 37-40 ◽

Cited By ~ 2

Author(s):

Huibin Han ◽

Hana Rakusová ◽

Inge Verstraeten ◽

Yuzhou Zhang ◽

Jiří Friml

Keyword(s):

Auxin Signaling ◽

Shoot Gravitropism

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An improved auxin-inducible degron system for fission yeast

10.1101/2021.07.19.452993 ◽

2021 ◽

Author(s):

Xiao-Ran Zhang ◽

Lei Zhao ◽

Fang Suo ◽

Yadong Gao ◽

Qingcui Wu ◽

...

Keyword(s):

Fission Yeast ◽

Binding Pocket ◽

Essential Genes ◽

Biological Research ◽

Auxin Signaling ◽

Loss Of Function ◽

Enhance Efficiency ◽

F Box Protein ◽

Signaling Components ◽

Control Protein

ABSTRACTConditional degron technologies, which allow a protein of interest to be degraded in an inducible manner, are important tools for biological research, and are especially useful for creating conditional loss-of-function mutants of essential genes. The auxin-inducible degron (AID) technology, which utilizes plant auxin signaling components to control protein degradation in non-plant species, is a widely used small-molecular-controlled degradation method in yeasts and animals. However, the currently available AID systems still have room for further optimization. Here, we have improved the AID system for the fission yeast Schizosaccharomyces pombe by optimizing all three components: the AID degron, the small-molecule inducer, and the inducer-responsive F-box protein. We chose a 36-amino-acid sequence of the Arabidopsis IAA17 protein as the degron and employed three tandem copies of it to enhance efficiency. To minimize undesirable side effects of the inducer, we adopted a bulky analog of auxin, 5-adamantyl-IAA, and paired it with the F-box protein OsTIR1 that harbors a mutation (F74A) at the auxin-binding pocket. 5-adamantyl-IAA, when utilized with OsTIR1-F74A, is effective at concentrations thousands of times lower than auxin used in combination with wild-type OsTIR1. We tested our improved AID system on 10 essential genes and achieved inducible lethality for all of them, including ones that could not be effectively inactivated using a previously published AID system. Our improved AID system should facilitate the construction of conditional loss-of-function mutants in fission yeast.

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Sirtinol, a Sir2 protein inhibitor, affects stem cell maintenance and root development in Arabidopsis thaliana by modulating auxin-cytokinin signaling components

Scientific Reports ◽

10.1038/srep42450 ◽

2017 ◽

Vol 7 (1) ◽

Cited By ~ 9

Author(s):

Sharmila Singh ◽

Alka Singh ◽

Sandeep Yadav ◽

Vibhav Gautam ◽

Archita Singh ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Stem Cell ◽

Auxin Signaling ◽

Cytokinin Signaling ◽

Cytokinin Biosynthesis ◽

Stem Cell Maintenance ◽

Meristem Maintenance ◽

2,4 Dichlorophenoxyacetic Acid ◽

Signaling Components ◽

Cell Maintenance

Abstract In Arabidopsis thaliana, besides several key transcription factors and chromatin modifiers, phytohormones auxin and cytokinin play pivotal role in shoot and root meristem maintenance, and lateral root (LR) development. Sirtinol, a chemical inhibitor of Sir2 proteins, is known to promote some auxin induced phenotypes in Arabidopsis. However, its effect on plant stem cell maintenance or organ formation remained unaddressed. Here we show that sirtinol affects meristem maintenance by altering the expression of key stem cell regulators, cell division and differentiation by modulating both auxin and cytokinin signaling in Arabidopsis thaliana. The expression of shoot stem cell niche related genes WUSCHEL (WUS) and CLAVATA3 (CLV3) was upregulated, whereas SHOOT MERISTEMLESS (STM) was downregulated in sirtinol treated seedlings. The expression level and domain of key root stem cell regulators PLETHORA (PLTs) and WUS-Related Homeobox 5 (WOX5) were altered in sirtinol treated roots. Sirtinol affects LR development by disturbing proper auxin transport and maxima formation, similar to 2,4-dichlorophenoxyacetic acid (2,4-D). Sirtinol also affects LR formation by altering cytokinin biosynthesis and signaling genes in roots. Therefore, sirtinol affects shoot and root growth, meristem maintenance and LR development by altering the expression of cytokinin-auxin signaling components, and regulators of stem cells, meristems, and LRs.

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The Hoja loca1 Mutant and AUX/IAA Function in Maize

10.1101/2020.03.27.012211 ◽

2020 ◽

Author(s):

A. E. Richardson ◽

A. Sluis ◽

S. Hake

Keyword(s):

Functional Redundancy ◽

Vital Role ◽

Land Plants ◽

Auxin Signaling ◽

Organ Development ◽

Loss Of Function ◽

Plant Organ ◽

Species Specific ◽

Signaling Components

AbstractAuxin plays a vital role in plant organ development, influencing organ initiation and patterning across all axes. The diversity in auxin patterning results from changes in the activities and expression of auxin signaling components, including the AUX/IAA repressors. Higher land plants have multigene AUX/IAA families, which leads to functional redundancy and a lack of phenotype in loss of function mutants. Instead, dominant mutations, which prevent AUX/IAA degradation in response to auxin, have highlighted the importance of these proteins in organ development. Here we report a new dominant AUX/IAA mutant in maize, Hoja loca1 (Oja). Oja has a mutation in the degron motif of ZmIAA28 and affects aerial organ initiation and medio-lateral patterning in the leaf. These phenotypes contrast with other maize AUX/IAA mutants that affect the root or inflorescence only. Oja illustrates the role of auxin signaling in the tight coordination of phytomer unit development and provides evidence of species-specific sub-functionalization of the AUX/IAAs.One Line SummaryThe maize AUX/IAA ZmIAA38 is involved in phytomer coordination, aerial organ initiation and mediolateral patterning, and illustrates species specific sub-functionalization of the AUX/IAAs.

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