Faculty Opinions recommendation of The AFB4 auxin receptor is a negative regulator of auxin signaling in seedlings.

Soil salinity is a key problem for crop production worldwide. High salt concentration in soil negatively modulates plant growth and development. In roots, salinity affects the growth and development of both primary and lateral roots. The phytohormone auxin regulates various developmental processes during the plant’s life cycle, including several aspects of root architecture. Auxin signaling involves the perception by specialized receptors which module several regulatory pathways. Despite their redundancy, previous studies have shown that their functions can also be context-specific depending on tissue, developmental or environmental cues. Here we show that the over-expression of Auxin Signaling F-Box 3 receptor results in an increased resistance to salinity in terms of root architecture and germination. We also studied possible downstream signaling components to further characterize the role of auxin in response to salt stress. We identify the transcription factor SZF1 as a key component in auxin-dependent salt stress response through the regulation of NAC4. These results give lights of an auxin-dependent mechanism that leads to the modulation of root system architecture in response to salt identifying a hormonal cascade important for stress response.

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A synthetic approach reveals a highly sensitive maize auxin response circuit

10.1101/844100 ◽

2019 ◽

Author(s):

Román Ramos Báez ◽

Yuli Buckley ◽

Han Yu ◽

Zongliang Chen ◽

Andrea Gallavotti ◽

...

Keyword(s):

Auxin Signaling ◽

Synthetic Approach ◽

Auxin Response ◽

Auxin Receptor ◽

Repressor Proteins ◽

Highly Sensitive ◽

Signaling Function ◽

Wide Range ◽

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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Overexpression of γ-glutamylcysteine synthetase gene from Caragana korshinskii decreases stomatal density and enhances drought tolerance

BMC Plant Biology ◽

10.1186/s12870-021-03226-9 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Baiyan Lu ◽

Xinjuan Luo ◽

Chunmei Gong ◽

Juan Bai

Keyword(s):

Drought Tolerance ◽

Mrna Expression ◽

Stress Responses ◽

Stomatal Density ◽

Negative Regulator ◽

Auxin Signaling ◽

Stomatal Development ◽

Endogenous Expression ◽

Caragana Korshinskii ◽

Glutamylcysteine Synthetase

Abstract Background Gamma-glutamylcysteine synthetase (γ-ECS) is a rate-limiting enzyme in glutathione biosynthesis and plays a key role in plant stress responses. In this study, the endogenous expression of the Caragana korshinskiiγ-ECS (Ckγ-ECS) gene was induced by PEG 6000-mediated drought stress in the leaves of C. korshinskii. and the Ckγ-ECS overexpressing transgenic Arabidopsis thaliana plants was constructed using the C. korshinskii. isolated γ-ECS. Results Compared with the wildtype, the Ckγ-ECS overexpressing plants enhanced the γ-ECS activity, reduced the stomatal density and aperture sizes; they also had higher relative water content, lower water loss, and lower malondialdehyde content. At the same time, the mRNA expression of stomatal development-related gene EPF1 was increased and FAMA and STOMAGEN were decreased. Besides, the expression of auxin-relative signaling genes AXR3 and ARF5 were upregulated. Conclusions These changes suggest that transgenic Arabidopsis improved drought tolerance, and Ckγ-ECS may act as a negative regulator in stomatal development by regulating the mRNA expression of EPF1 and STOMAGEN through auxin signaling.

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Expression and Role of Biosynthetic, Transporter, Receptor, and Responsive Genes for Auxin Signaling during Clubroot Disease Development

International Journal of Molecular Sciences ◽

10.3390/ijms21155554 ◽

2020 ◽

Vol 21 (15) ◽

pp. 5554

Author(s):

Arif Hasan Khan Robin ◽

Gopal Saha ◽

Rawnak Laila ◽

Jong-In Park ◽

Hoy-Taek Kim ◽

...

Keyword(s):

Plasmodiophora Brassicae ◽

Fold Increase ◽

Auxin Signaling ◽

Post Inoculation ◽

Disease Development ◽

Secondary Phases ◽

Auxin Receptor ◽

Clubroot Disease ◽

Root Tissues

Auxins play a pivotal role in clubroot development caused by the obligate biotroph Plasmodiophora brassicae. In this study, we investigated the pattern of expression of 23 genes related to auxin biosynthesis, reception, and transport in Chinese cabbage (Brassica rapa) after inoculation with P. brassicae. The predicted proteins identified, based on the 23 selected auxin-related genes, were from protein kinase, receptor kinase, auxin responsive, auxin efflux carrier, transcriptional regulator, and the auxin-repressed protein family. These proteins differed in amino acids residue, molecular weights, isoelectric points, chromosomal location, and subcellular localization. Leaf and root tissues showed dynamic and organ-specific variation in expression of auxin-related genes. The BrGH3.3 gene, involved in auxin signaling, exhibited 84.4-fold increase in expression in root tissues compared to leaf tissues as an average of all samples. This gene accounted for 4.8-, 2.6-, and 5.1-fold higher expression at 3, 14, and 28 days post inoculation (dpi) in the inoculated root tissues compared to mock-treated roots. BrNIT1, an auxin signaling gene, and BrPIN1, an auxin transporter, were remarkably induced during both cortex infection at 14 dpi and gall formation at 28 dpi. BrDCK1, an auxin receptor, was upregulated during cortex infection at 14 dpi. The BrLAX1 gene, associated with root hair development, was induced at 1 dpi in infected roots, indicating its importance in primary infection. More interestingly, a significantly higher expression of BrARP1, an auxin-repressed gene, at both the primary and secondary phases of infection indicated a dynamic response of the host plant towards its resistance against P. brassicae. The results of this study improve our current understanding of the role of auxin-related genes in clubroot disease development.

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Histone deacetylase HDA6 enhances brassinosteroid signaling by inhibiting the BIN2 kinase

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1521363113 ◽

2016 ◽

Vol 113 (37) ◽

pp. 10418-10423 ◽

Cited By ~ 32

Author(s):

Yuhan Hao ◽

Haijiao Wang ◽

Shenglong Qiao ◽

Linna Leng ◽

Xuelu Wang

Keyword(s):

Histone Deacetylase ◽

Stress Responses ◽

Kinase Activity ◽

Glycogen Synthase ◽

Negative Regulator ◽

Glycogen Synthase Kinase 3 ◽

Auxin Signaling ◽

Energy Status ◽

Cellular Energy ◽

Brassinosteroid Signaling

Glycogen synthase kinase 3 (GSK3)-like kinases play important roles in brassinosteroid (BR), abscisic acid, and auxin signaling to regulate many aspects of plant development and stress responses. The Arabidopsis thaliana GSK3-like kinase BR-INSENSITIVE 2 (BIN2) acts as a key negative regulator in the BR signaling pathway, but the mechanisms regulating BIN2 function remain unclear. Here we report that the histone deacetylase HDA6 can interact with and deacetylate BIN2 to repress its kinase activity. The hda6 mutant showed a BR-repressed phenotype in the dark and was less sensitive to BR biosynthesis inhibitors. Genetic analysis indicated that HDA6 regulates BR signaling through BIN2. Furthermore, we identified K189 of BIN2 as an acetylated site, which can be deacetylated by HDA6 to influence BIN2 activity. Glucose can affect the acetylation level of BIN2 in plants, indicating a connection to cellular energy status. These findings provide significant insights into the regulation of GSK3-like kinases in plant growth and development.

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Nitric oxide influences auxin signaling through S-nitrosylation of the Arabidopsis TRANSPORT INHIBITOR RESPONSE 1 auxin receptor

The Plant Journal ◽

10.1111/j.1365-313x.2011.04885.x ◽

2012 ◽

Vol 70 (3) ◽

pp. 492-500 ◽

Cited By ~ 184

Author(s):

María C. Terrile ◽

Ramiro París ◽

Luz I. A. Calderón-Villalobos ◽

María J. Iglesias ◽

Lorenzo Lamattina ◽

...

Keyword(s):

Nitric Oxide ◽

Auxin Signaling ◽

Auxin Receptor ◽

Transport Inhibitor

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Auxin binding protein 1 (ABP1) is not required for either auxin signaling or Arabidopsis development

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1500365112 ◽

2015 ◽

Vol 112 (7) ◽

pp. 2275-2280 ◽

Cited By ~ 196

Author(s):

Yangbin Gao ◽

Yi Zhang ◽

Da Zhang ◽

Xinhua Dai ◽

Mark Estelle ◽

...

Keyword(s):

Binding Protein ◽

Start Codon ◽

Null Alleles ◽

Auxin Signaling ◽

Wild Type ◽

Auxin Receptor ◽

Developmental Defects ◽

Auxin Binding ◽

Dna Insertion ◽

Auxin Binding Protein

Auxin binding protein 1 (ABP1) has been studied for decades. It has been suggested that ABP1 functions as an auxin receptor and has an essential role in many developmental processes. Here we present our unexpected findings that ABP1 is neither required for auxin signaling nor necessary for plant development under normal growth conditions. We used our ribozyme-based CRISPR technology to generate an Arabidopsis abp1 mutant that contains a 5-bp deletion in the first exon of ABP1, which resulted in a frameshift and introduction of early stop codons. We also identified a T-DNA insertion abp1 allele that harbors a T-DNA insertion located 27 bp downstream of the ATG start codon in the first exon. We show that the two new abp1 mutants are null alleles. Surprisingly, our new abp1 mutant plants do not display any obvious developmental defects. In fact, the mutant plants are indistinguishable from wild-type plants at every developmental stage analyzed. Furthermore, the abp1 plants are not resistant to exogenous auxin. At the molecular level, we find that the induction of known auxin-regulated genes is similar in both wild-type and abp1 plants in response to auxin treatments. We conclude that ABP1 is not a key component in auxin signaling or Arabidopsis development.

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