| 1. |
- Gendre, Delphine, et al.
(författare)
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Rho-of-plant activated root hair formation requires Arabidopsis YIP4a/b gene function
- 2019
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Ingår i: Development. - : The Company of Biologists. - 0950-1991 .- 1477-9129. ; 146:5
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Tidskriftsartikel (refereegranskat)abstract
- Root hairs are protrusions from root epidermal cells with crucial roles in plant soil interactions. Although much is known about patterning, polarity and tip growth of root hairs, contributions of membrane trafficking to hair initiation remain poorly understood. Here, we demonstrate that the trans-Golgi network-localized YPT-INTERACTING PROTEIN 4a and YPT-INTERACTING PROTEIN 4b (YIP4a/b) contribute to activation and plasma membrane accumulation of Rho-of-plant (ROP) small GTPases during hair initiation, identifying YIP4a/b as central trafficking components in ROP-dependent root hair formation.
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| 2. |
- Antoniadi, Ioanna, et al.
(författare)
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Cell-surface receptors enable perception of extracellular cytokinins
- 2020
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Cytokinins are mobile multifunctional plant hormones with roles in development and stress resilience. Although their Histidine Kinase receptors are substantially localised to the endoplasmic reticulum, cellular sites of cytokinin perception and importance of spatially heterogeneous cytokinin distribution continue to be debated. Here we show that cytokinin perception by plasma membrane receptors is an effective additional path for cytokinin response. Readout from a Two Component Signalling cytokinin-specific reporter (TCSn::GFP) closely matches intracellular cytokinin content in roots, yet we also find cytokinins in extracellular fluid, potentially enabling action at the cell surface. Cytokinins covalently linked to beads that could not pass the plasma membrane increased expression of both TCSn::GFP and Cytokinin Response Factors. Super-resolution microscopy of GFP-labelled receptors and diminished TCSn::GFP response to immobilised cytokinins in cytokinin receptor mutants, further indicate that receptors can function at the cell surface. We argue that dual intracellular and surface locations may augment flexibility of cytokinin responses. The main site of cytokinin perception in plant cells is thought to be the endoplasmic reticulum where most cytokinin receptors localise. Here via the use of bioactive probes that cannot enter plant cells and super-resolution microscopy, Antoniadi et al. show that cytokinin can also be perceived at the plasma membrane.
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| 3. |
- Doyle, Siamsa, et al.
(författare)
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An early secretory pathway mediated by GNOM-LIKE 1 and GNOM is essential for basal polarity establishment in Arabidopsis thaliana
- 2015
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 112:7, s. E806-E815
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Tidskriftsartikel (refereegranskat)abstract
- Spatial regulation of the plant hormone indole-3-acetic acid (IAA, or auxin) is essential for plant development. Auxin gradient establishment is mediated by polarly localized auxin transporters, including PIN-FORMED (PIN) proteins. Their localization and abundance at the plasma membrane are tightly regulated by endo-membrane machinery, especially the endocytic and recycling pathways mediated by the ADP ribosylation factor guanine nucleotide exchange factor (ARF-GEF) GNOM. We assessed the role of the early secretory pathway in establishing PIN1 polarity in Arabidopsis thaliana by pharmacological and genetic approaches. We identified the compound endosidin 8 (ES8), which selectively interferes with PIN1 basal polarity without altering the polarity of apical proteins. ES8 alters the auxin distribution pattern in the root and induces a strong developmental phenotype, including reduced root length. The ARF-GEF-defective mutants gnom-like 1 (gnl1-1) and gnom (van7) are significantly resistant to ES8. The compound does not affect recycling or vacuolar trafficking of PIN1 but leads to its intracellular accumulation, resulting in loss of PIN1 basal polarity at the plasma membrane. Our data confirm a role for GNOM in endoplasmic reticulum (ER)-Golgi trafficking and reveal that a GNL1/GNOM-mediated early secretory pathway selectively regulates PIN1 basal polarity establishment in a manner essential for normal plant development.
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| 4. |
- Doyle, Siamsa, et al.
(författare)
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Small molecules unravel complex interplay between auxin biology and endomembrane trafficking
- 2015
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Ingår i: Journal of Experimental Botany. - : Oxford University Press (OUP). - 0022-0957 .- 1460-2431. ; 66, s. 4971-4982
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Forskningsöversikt (refereegranskat)abstract
- The establishment and maintenance of controlled auxin gradients within plant tissues are essential for a multitude of developmental processes. Auxin gradient formation is co-ordinated via local biosynthesis and transport. Cell to cell auxin transport is facilitated and precisely regulated by complex endomembrane trafficking mechanisms that target auxin carrier proteins to their final destinations. In turn, auxin and cross-talk with other phytohormones regulate the endomembrane trafficking of auxin carriers. Dissecting such rapid and complicated processes is challenging for classical genetic experiments due to trafficking pathway diversity, gene functional redundancy, and lethality in lossof-function mutants. Many of these difficulties can be bypassed via the use of small molecules to modify or disrupt the function or localization of proteins. Here, we will review examples of the knowledge acquired by the use of such chemical tools in this field, outlining the advantages afforded by chemical biology approaches.
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| 5. |
- Liu, Qinsong, et al.
(författare)
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Vacuole Integrity Maintained by DUF300 Proteins Is Required for Brassinosteroid Signaling Regulation
- 2018
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Ingår i: Molecular Plant. - : Cell Press. - 1674-2052 .- 1752-9867. ; 11:4, s. 553-567
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Tidskriftsartikel (refereegranskat)abstract
- Brassinosteroid (BR) hormone signaling controls multiple processes during plant growth and development and is initiated at the plasma membrane through the receptor kinase BRASSINOSTEROID INSENSITIVE1 (BRI1) together with co-receptors such as BRI1-ASSOCIATED RECEPTOR KINASE1 (BAK1). BRI1 abundance is regulated by endosomal recycling and vacuolar targeting, but the role of vacuole-related proteins in BR receptor dynamics and BR responses remains elusive. Here, we show that the absence of two DUF300 domain-containing tonoplast proteins, LAZARUS1 (LAZ1) and LAZ1 HOMOLOG1 (LAZ1H1), causes vacuole morphology defects, growth inhibition, and constitutive activation of BR signaling. Intriguingly, tonoplast accumulation of BAK1 was substantially increased and appeared causally linked to enhanced BRI1 trafficking and degradation in laz1 laz1h1 plants. Since unrelated vacuole mutants exhibited normal BR responses, our findings indicate that DUF300 proteins play distinct roles in the regulation of BR signaling by maintaining vacuole integrity required to balance subcellular BAK1 pools and BR receptor distribution.
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| 6. |
- Majda, Mateusz, et al.
(författare)
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Mechanochemical Polarization of Contiguous Cell Walls Shapes Plant Pavement Cells
- 2017
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Ingår i: Developmental Cell. - : Elsevier BV. - 1534-5807 .- 1878-1551. ; 43:3, s. 4-304
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Tidskriftsartikel (refereegranskat)abstract
- The epidermis of aerial plant organs is thought to be limiting for growth, because it acts as a continuous load-bearing layer, resisting tension. Leaf epidermis contains jigsaw puzzle piece-shaped pavement cells whose shape has been proposed to be a result of subcellular variations in expansion rate that induce local buckling events. Paradoxically, such local compressive buckling should not occur given the tensile stresses across the epidermis. Using computational modeling, we show that the simplest scenario to explain pavement cell shapes within an epidermis under tension must involve mechanical wall heterogeneities across and along the anticlinal pavement cell walls between adjacent cells. Combining genetics, atomic force microscopy, and immunolabeling, we demonstrate that contiguous cell walls indeed exhibit hybrid mechanochemical properties. Such biochemical wall heterogeneities precede wall bending. Altogether, this provides a possible mechanism for the generation of complex plant cell shapes. Pavement cells in the leaf epidermis are multi-lobed like jigsaw puzzle pieces. Majda et al. provide evidence through in vivo analyses using atomic force microscopy and computational modeling that mechanical heterogeneities across and along anticlinal cell walls allow wall bending that contributes to lobe formation and these complex cell shapes.
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| 7. |
- Rigal, Adeline, et al.
(författare)
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A network of stress-related genes regulates hypocotyl elongation downstream of selective auxin perception
- 2021
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 187, s. 430-445
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Tidskriftsartikel (refereegranskat)abstract
- The plant hormone auxin, a master coordinator of development, regulates hypocotyl elongation during seedling growth. We previously identified the synthetic molecule RubNeddin 1 (RN1), which induces degradation of the AUXIN/INDOLE-3-ACETIC ACID (AUX/IAA) transcriptional repressors INDOLE-3-ACETIC ACID-INDUCIBLE3 (IAA3) and IAA7 in planta and strongly promotes hypocotyl elongation. In the present study, we show that despite the structural similarity of RN1 to the synthetic auxin 2,4-dichlorophenoxyacetic-acid (2,4-D), direct treatments with these compounds in Arabidopsis (Arabidopsis thaliana) result in distinct effects, possibly due to enhanced uptake of RN1 and low-level, chronic release of 2,4-D from RN1 in planta. We confirm RN1-induced hypocotyl elongation occurs via specific TRANSPORT INHIBITOR RESISTANT1 (TIR1)/AUXIN SIGNALING F-BOX (AFB) receptor-mediated auxin signaling involving TIR1, AFB2, and AFB5. Using a transcriptome profiling strategy and candidate gene approach, we identify the genes ZINC FINGER OF ARABIDOPSIS THALIANA10 (ZAT10), ARABIDOPSIS TOXICOS EN LEVADURA31 (ATL31), and WRKY DNA-BINDING PROTEIN33 (WRKY33) as being rapidly upregulated by RN1, despite being downregulated by 2,4-D treatment. RN1-induced expression of these genes also occurs via TIR1/AFB-mediated auxin signaling. Our results suggest both hypocotyl elongation and transcription of these genes are induced by RN1 via the promoted degradation of the AUX/IAA transcriptional repressor IAA7. Moreover, these three genes, which are known to be stress-related, act in an inter-dependent transcriptional regulatory network controlling hypocotyl elongation. Together, our results suggest ZAT10, ATL31, and WRKY33 take part in a common gene network regulating hypocotyl elongation in Arabidopsis downstream of a selective auxin perception module likely involving TIR1, AFB2, and AFB5 and inducing the degradation of IAA7.
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| 8. |
- Seyfferth, Carolin, et al.
(författare)
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Ethylene Signaling Is Required for Fully Functional Tension Wood in Hybrid Aspen
- 2019
-
Ingår i: Frontiers in Plant Science. - : Frontiers Media S.A.. - 1664-462X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Tension wood (TW) in hybrid aspen trees forms on the upper side of displaced stems to generate a strain that leads to uplifting of the stem. TW is characterized by increased cambial growth, reduced vessel frequency and diameter, and the presence of gelatinous, cellulose-rich (G-)fibers with its microfibrils oriented parallel to the fiber cell axis. Knowledge remains limited about the molecular regulators required for the development of this special xylem tissue with its characteristic morphological, anatomical, and chemical features. In this study, we use transgenic, ethylene-insensitive (ETI) hybrid aspen trees together with time-lapse imaging to show that functional ethylene signaling is required for full uplifting of inclined stems. X-ray diffraction and Raman microspectroscopy of TW in ETI trees indicate that, although G-fibers form, the cellulose microfibril angle in the G-fiber S-layer is decreased, and the chemical composition of S- and G-layers is altered than in wild-type TW. The characteristic asymmetric growth and reduction of vessel density is suppressed during TW formation in ETI trees. A genome-wide transcriptome profiling reveals ethylene-dependent genes in TW, related to cell division, cell wall composition, vessel differentiation, microtubule orientation, and hormone crosstalk. Our results demonstrate that ethylene regulates transcriptional responses related to the amount of G-fiber formation and their properties (chemistry and cellulose microfibril angle) during TW formation. The quantitative and qualitative changes in G-fibers are likely to contribute to uplifting of stems that are displaced from their original position.
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| 9. |
- Vain, Thomas
(författare)
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Chemical biology and digital image processing to unravel complex molecular mechanisms in Arabidopsis
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The sessile life of plant directed their evolution toward multiple adaptive strategies. Rapid protein turn over has been described to be a key regulatory mechanism for plant adaptation. Ubiquitin-modified proteins are targeted for degradation by the 26S-proteasome. A class of ubiquitin-ligases, the Cullin Ring Ligases (CRLs) have been shown to be involved in most Arabidopsis developmental processes. CRLs are stabilized by the covalent binding of the small peptide RELATED TO UBIQUITIN (RUB). The CRLs modification is required for the activity of plant hormones as exemplified by mutants deficient in the RUB-activating enzyme subunit AUXIN-RESISTANT 1 (AXR1). The perception of auxin results in the ubiquitin-mediated degradation of the AUXIN/INDOL-3-ACETIC ACID (Aux/IAA) transcriptional repressors. Aux/IAA proteins control the auxin-mediated transcriptional response. In this work, a forward chemical genomic strategy has been used to identify small synthetic molecules affecting plant development. We used the resistance of the axr1-30 mutants in order to select compounds requiring RUB activation. Among the molecules isolated to alter specific plant developmental processes, three Developmental Regulators (DRs) have been shown to directly interfere with the degradation of the Aux/IAA proteins promoting a rapid induction of specific auxin-related transcriptional responses. Furthermore, we used the molecule DR4, abolishing specifically apical hook formation, to investigate the functional selectivity of auxin perception during apical hook development. A forward genetic screen has been performed to isolate dr4-resistant mutants. Several viable mutants were isolated with different sensitivity to auxin but all resistant to DR4. The isolation of mutants preferentially resistant to the differential growth defect induced by DR4 demonstrates the potential to determine the molecular process mediating the developmental features induced by the selective agonists of auxin. Since the first digital image 60 years ago, imaging techniques are constantly evolving generating more and more digital images. The conversion of images into biologically relevant quantitative data is an essential process to overcome and understand biological variability. In this work, we describe two digital images processing approaches which have been used to semi-automatically describe intracellular structure density and colocalization; the complex shape of the Arabidopsis pavement cells.
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| 10. |
- Vain, Thomas, et al.
(författare)
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New fluorescent auxin probes visualise tissue-specific and subcellular distributions of auxin in Arabidopsis
- 2021
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 230, s. 535-549
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Tidskriftsartikel (refereegranskat)abstract
- In a world that will rely increasingly on efficient plant growth for sufficient food, it is important to learn about natural mechanisms of phytohormone action. In this work, the introduction of a fluorophore to an auxin molecule represents a sensitive and non-invasive method to directly visualise auxin localisation with high spatiotemporal resolution.The state-of-the-art multidisciplinary approaches of genetic and chemical biology analysis together with live cell imaging, liquid chromatography-mass spectrometry (LC-MS) and surface plasmon resonance (SPR) methods were employed for the characterisation of auxin-related biological activity, distribution and stability of the presented compounds in Arabidopsis thaliana.Despite partial metabolisation in vivo, these fluorescent auxins display an uneven and dynamic distribution leading to the formation of fluorescence maxima in tissues known to concentrate natural auxin, such as the concave side of the apical hook. Importantly, their distribution is altered in response to different exogenous stimuli in both roots and shoots. Moreover, we characterised the subcellular localisation of the fluorescent auxin analogues as being present in the endoplasmic reticulum and endosomes.Our work provides powerful tools to visualise auxin distribution within different plant tissues at cellular or subcellular levels and in response to internal and environmental stimuli during plant development.
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