1
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Meier MC, Lewis NS, Carim AI. Inclination of polarized illumination increases symmetry of structures grown via inorganic phototropism. MATERIALS HORIZONS 2023; 10:4251-4255. [PMID: 37581003 DOI: 10.1039/d3mh00839h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
Inclination of unpatterned, linearly polarized illumination in the plane of the electric field oscillation effected increased directional feature alignment and decreased off-axis order in Se-Te deposits generated by inorganic phototropic growth relative to that produced using normal incidence. Optically based growth simulations reproduced the experimental results indicating a photonic basis for the morphology change. Modeling of the light scattering at the growth interface revealed that illumination inclination enhances scattering that localizes the optical field along the polarization plane and suppresses cooperativity in defect-driven scattering. Thus, the symmetry of the deposited structures increased as the asymmetry of the illumination increased, as measured by the inclination of the illumination incidence away from the surface normal.
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Affiliation(s)
- Madeline C Meier
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
| | - Nathan S Lewis
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
- Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA
| | - Azhar I Carim
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
- Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA
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2
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Lv QY, Zhao QP, Zhu C, Ding M, Chu FY, Li XK, Cheng K, Zhao X. Hydrogen peroxide mediates high-intensity blue light-induced hypocotyl phototropism of cotton seedlings. STRESS BIOLOGY 2023; 3:27. [PMID: 37676397 PMCID: PMC10442013 DOI: 10.1007/s44154-023-00111-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 07/16/2023] [Indexed: 09/08/2023]
Abstract
Phototropism is a classic adaptive growth response that helps plants to enhance light capture for photosynthesis. It was shown that hydrogen peroxide (H2O2) participates in the regulation of blue light-induced hypocotyl phototropism; however, the underlying mechanism is unclear. In this study, we demonstrate that the unilateral high-intensity blue light (HBL) could induce asymmetric distribution of H2O2 in cotton hypocotyls. Disruption of the HBL-induced asymmetric distribution of H2O2 by applying either H2O2 itself evenly on the hypocotyls or H2O2 scavengers on the lit side of hypocotyls could efficiently inhibit hypocotyl phototropic growth. Consistently, application of H2O2 on the shaded and lit sides of the hypocotyls led to reduced and enhanced hypocotyl phototropism, respectively. Further, we show that H2O2 inhibits hypocotyl elongation of cotton seedlings, thus supporting the repressive role of H2O2 in HBL-induced hypocotyl phototropism. Moreover, our results show that H2O2 interferes with HBL-induced asymmetric distribution of auxin in the cotton hypocotyls. Taken together, our study uncovers that H2O2 changes the asymmetric accumulation of auxin and inhibits hypocotyl cell elongation, thus mediating HBL-induced hypocotyl phototropism.
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Affiliation(s)
- Qian-Yi Lv
- National Key Laboratory of Cotton Bio-Breeding and Integrated Utilization, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Qing-Ping Zhao
- National Key Laboratory of Cotton Bio-Breeding and Integrated Utilization, School of Life Sciences, Henan University, Kaifeng, 475004, China
- College of Life Science and Agricultural Engineering, Nanyang Normal University, 1638 Wolong Road, Nanyang, 473061, Henan, China
| | - Chen Zhu
- National Key Laboratory of Cotton Bio-Breeding and Integrated Utilization, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Meichen Ding
- National Key Laboratory of Cotton Bio-Breeding and Integrated Utilization, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Fang-Yuan Chu
- National Key Laboratory of Cotton Bio-Breeding and Integrated Utilization, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Xing-Kun Li
- National Key Laboratory of Cotton Bio-Breeding and Integrated Utilization, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Kai Cheng
- National Key Laboratory of Cotton Bio-Breeding and Integrated Utilization, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Xiang Zhao
- National Key Laboratory of Cotton Bio-Breeding and Integrated Utilization, School of Life Sciences, Henan University, Kaifeng, 475004, China.
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3
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Plant cell-like tip-growing polymer precipitate with structurally embedded multistimuli sensing ability. Proc Natl Acad Sci U S A 2023; 120:e2211416120. [PMID: 36595665 PMCID: PMC9926264 DOI: 10.1073/pnas.2211416120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Soft systems that respond to external stimuli, such as heat, magnetic field, and light, find applications in a range of fields including soft robotics, energy harvesting, and biomedicine. However, most of the existing systems exhibit nondirectional, nastic movement as they can neither grow nor sense the direction of stimuli. In this regard, artificial systems are outperformed by organisms capable of directional growth in response to the sense of stimuli or tropic growth. Inspired by tropic growth schemes of plant cells and fungal hyphae, here we report an artificial multistimuli-responsive tropic tip-growing system based on nonsolvent-induced phase separation of polymer solution, where polymer precipitates as its solvent dissolves into surrounding nonsolvent. We provide a theoretical framework to predict the size and velocity of growing precipitates and demonstrate its capability of sensing the directions of gravity, mechanical contact, and light and adjusting its growing direction in response. Exploiting the embedded physical intelligence of sensing and responding to external stimuli, our soft material system achieves multiple tasks including printing 3D structures in a confined space, bypassing mechanical obstacles, and shielded transport of liquids within water.
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4
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Jonsson K, Ma Y, Routier-Kierzkowska AL, Bhalerao RP. Multiple mechanisms behind plant bending. NATURE PLANTS 2023; 9:13-21. [PMID: 36581759 DOI: 10.1038/s41477-022-01310-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 11/08/2022] [Indexed: 06/17/2023]
Abstract
To survive, plants constantly adapt their body shape to their environment. This often involves remarkably rapid bending of their organs such as stems, leaves and roots. Since plant cells are enclosed by stiff cell walls, they use various strategies for bending their organs, which differ from bending mechanisms of soft animal tissues and involve larger physical forces. Here we attempt to summarize and link different viewpoints on bending mechanisms: genes and signalling, mathematical modelling and biomechanics. We argue that quantifying cell growth and physical forces could open a new level in our understanding of bending and resolve some of its paradoxes.
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Affiliation(s)
- Kristoffer Jonsson
- IRBV, Department of Biological Sciences, University of Montreal, Montreal, Quebec, Canada
| | - Yuan Ma
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden
| | | | - Rishikesh P Bhalerao
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden.
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5
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Xin GY, Li LP, Wang PT, Li XY, Han YJ, Zhao X. The action of enhancing weak light capture via phototropic growth and chloroplast movement in plants. STRESS BIOLOGY 2022; 2:50. [PMID: 37676522 PMCID: PMC10441985 DOI: 10.1007/s44154-022-00066-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 10/11/2022] [Indexed: 09/08/2023]
Abstract
To cope with fluctuating light conditions, terrestrial plants have evolved precise regulation mechanisms to help optimize light capture and increase photosynthetic efficiency. Upon blue light-triggered autophosphorylation, activated phototropin (PHOT1 and PHOT2) photoreceptors function solely or redundantly to regulate diverse responses, including phototropism, chloroplast movement, stomatal opening, and leaf positioning and flattening in plants. These responses enhance light capture under low-light conditions and avoid photodamage under high-light conditions. NON-PHOTOTROPIC HYPOCOTYL 3 (NPH3) and ROOT PHOTOTROPISM 2 (RPT2) are signal transducers that function in the PHOT1- and PHOT2-mediated response. NPH3 is required for phototropism, leaf expansion and positioning. RPT2 regulates chloroplast accumulation as well as NPH3-mediated responses. NRL PROTEIN FOR CHLOROPLAST MOVEMENT 1 (NCH1) was recently identified as a PHOT1-interacting protein that functions redundantly with RPT2 to mediate chloroplast accumulation. The PHYTOCHROME KINASE SUBSTRATE (PKS) proteins (PKS1, PKS2, and PKS4) interact with PHOT1 and NPH3 and mediate hypocotyl phototropic bending. This review summarizes advances in phototropic growth and chloroplast movement induced by light. We also focus on how crosstalk in signaling between phototropism and chloroplast movement enhances weak light capture, providing a basis for future studies aiming to delineate the mechanism of light-trapping plants to improve light-use efficiency.
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Affiliation(s)
- Guang-Yuan Xin
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China
| | - Lu-Ping Li
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China
| | - Peng-Tao Wang
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China
| | - Xin-Yue Li
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China
| | - Yuan-Ji Han
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China
| | - Xiang Zhao
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China.
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6
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Brenya E, Pervin M, Chen ZH, Tissue DT, Johnson S, Braam J, Cazzonelli CI. Mechanical stress acclimation in plants: Linking hormones and somatic memory to thigmomorphogenesis. PLANT, CELL & ENVIRONMENT 2022; 45:989-1010. [PMID: 34984703 DOI: 10.1111/pce.14252] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 12/03/2021] [Accepted: 12/09/2021] [Indexed: 06/14/2023]
Abstract
A single event of mechanical stimulation is perceived by mechanoreceptors that transduce rapid transient signalling to regulate gene expression. Prolonged mechanical stress for days to weeks culminates in cellular changes that strengthen the plant architecture leading to thigmomorphogenesis. The convergence of multiple signalling pathways regulates mechanically induced tolerance to numerous biotic and abiotic stresses. Emerging evidence showed prolonged mechanical stimulation can modify the baseline level of gene expression in naive tissues, heighten gene expression, and prime disease resistance upon a subsequent pathogen encounter. The phenotypes of thigmomorphogenesis can persist throughout growth without continued stimulation, revealing somatic-stress memory. Epigenetic processes regulate TOUCH gene expression and could program transcriptional memory in differentiating cells to program thigmomorphogenesis. We discuss the early perception, gene regulatory and phytohormone pathways that facilitate thigmomorphogenesis and mechanical stress acclimation in Arabidopsis and other plant species. We provide insights regarding: (1) the regulatory mechanisms induced by single or prolonged events of mechanical stress, (2) how mechanical stress confers transcriptional memory to induce cross-acclimation to future stress, and (3) why thigmomorphogenesis might resemble an epigenetic phenomenon. Deeper knowledge of how prolonged mechanical stimulation programs somatic memory and primes defence acclimation could transform solutions to improve agricultural sustainability in stressful environments.
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Affiliation(s)
- Eric Brenya
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales, Australia
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, USA
| | - Mahfuza Pervin
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales, Australia
| | - Zhong-Hua Chen
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales, Australia
- School of Science, Western Sydney University, Richmond, New South Wales, Australia
| | - David T Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales, Australia
| | - Scott Johnson
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales, Australia
| | - Janet Braam
- Department of Biosciences, Rice University, Houston, Texas, USA
| | - Christopher I Cazzonelli
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales, Australia
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7
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Zeidler M. Physiological Analysis of Phototropic Responses to Blue and Red Light in Arabidopsis. Methods Mol Biol 2022; 2494:37-45. [PMID: 35467199 DOI: 10.1007/978-1-0716-2297-1_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Plants utilize light as sole energy source. To maximize light capture, they are able to detect the light direction and orient themselves toward the light source. This phototropic response is mediated by the plant blue-light photoreceptors phototropin1 and phototropin2 (phot1 and phot2). Although fully differentiated plants also exhibit this response, it can be best observed in etiolated seedlings. Differences in light between the illuminated and shaded site of a seedling stem lead to changes in the auxin distribution, resulting in cell elongation on the shaded site. Since phototropism connects light perception, signaling, and auxin transport, it is of great interest to analyze this response with a fast and simple method. Moreover, pre-exposure to red light enhances the phototropic response via phytochrome A (phyA) and phyB action. Here we describe a method to analyze the phototropic response of Arabidopsis seedlings to blue light and the enhanced response with a red-light pretreatment. With numerous mutants available, its fast germination, and its small size, Arabidopsis is well suited for this analysis. Different genotypes can be simultaneously probed in less than a week.
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Affiliation(s)
- Mathias Zeidler
- Institute of Plant Physiology, Justus-Liebig-University Giessen, Giessen, Germany.
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8
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Zhu J, Wang J, Sheng Y, Tian Y, Zhang Y, Zhou C, Zhao X, Zhang X. Phototropin2-mediated hypocotyl phototropism is negatively regulated by JAC1 and RPT2 in Arabidopsis. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2021; 164:289-298. [PMID: 34023643 DOI: 10.1016/j.plaphy.2021.05.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 05/03/2021] [Indexed: 06/12/2023]
Abstract
Hypocotyl phototropism is redundantly mediated by phot1 and phot2, two blue light receptor phototropins, under the intensity of blue light>1 μmol m-2 s-1. As light intensity increases, phot1 inhibits the phot2-mediated response. To date, only Arabidopsis Root Phototropism2 (RPT2) has been shown to participate in phot1-mediated inhibition of phototropism. To dissect the signaling network that underlies phot1-mediated inhibition, we carried out a yeast two-hybrid (Y2H) screening assay for RPT2 interacting proteins and identified J-domain protein required for chloroplast accumulation response 1 (JAC1). The interaction between JAC1 and RPT2 was verified by bimolecular fluorescence complementation and Co-IP assays. JAC1 is expressed mainly in cotyledons and hypocotyls. Like RPT2, JAC1 can be induced by blue light, suggesting that it may function similarly to RPT2 in the inhibition of phototropism. Genetic analysis showed that jac1 mutation significantly enhanced the hypocotyl bending of phot1 mutants towards intermediate-intensity blue light, and this effect was inhibited by the constitutive expression of JAC1 in the phot1 jac1 mutant. The phot1 rpt2 double mutant also exhibited enhanced phototropism compared with the phot1 mutant. Taken together, our data clearly demonstrate that JAC1 cooperates with RPT2 to negatively regulate hypocotyl phototropism in plants and may act either downstream of or in parallel with phot1.
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Affiliation(s)
- Jindong Zhu
- State Key Laboratory of Crop Stress Adaptation and Improvement, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng, 475001, China
| | - Jing Wang
- State Key Laboratory of Crop Stress Adaptation and Improvement, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng, 475001, China
| | - Yuanyuan Sheng
- State Key Laboratory of Crop Stress Adaptation and Improvement, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng, 475001, China
| | - Yan Tian
- State Key Laboratory of Crop Stress Adaptation and Improvement, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng, 475001, China
| | - Yueyue Zhang
- State Key Laboratory of Crop Stress Adaptation and Improvement, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng, 475001, China
| | - Chanjuan Zhou
- State Key Laboratory of Crop Stress Adaptation and Improvement, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng, 475001, China
| | - Xiang Zhao
- State Key Laboratory of Crop Stress Adaptation and Improvement, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng, 475001, China.
| | - Xiao Zhang
- State Key Laboratory of Crop Stress Adaptation and Improvement, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng, 475001, China.
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9
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Moulton DE, Oliveri H, Goriely A. Multiscale integration of environmental stimuli in plant tropism produces complex behaviors. Proc Natl Acad Sci U S A 2020; 117:32226-32237. [PMID: 33273121 PMCID: PMC7768784 DOI: 10.1073/pnas.2016025117] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Plant tropism refers to the directed movement of an organ or organism in response to external stimuli. Typically, these stimuli induce hormone transport that triggers cell growth or deformation. In turn, these local cellular changes create mechanical forces on the plant tissue that are balanced by an overall deformation of the organ, hence changing its orientation with respect to the stimuli. This complex feedback mechanism takes place in a three-dimensional growing plant with varying stimuli depending on the environment. We model this multiscale process in filamentary organs for an arbitrary stimulus by explicitly linking hormone transport to local tissue deformation leading to the generation of mechanical forces and the deformation of the organ in three dimensions. We show, as examples, that the gravitropic, phototropic, nutational, and thigmotropic dynamic responses can be easily captured by this framework. Further, the integration of evolving stimuli and/or multiple contradictory stimuli can lead to complex behavior such as sun following, canopy escape, and plant twining.
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Affiliation(s)
- Derek E Moulton
- Mathematical Institute, University of Oxford, Oxford OX2 6GG, United Kingdom
| | - Hadrien Oliveri
- Mathematical Institute, University of Oxford, Oxford OX2 6GG, United Kingdom
| | - Alain Goriely
- Mathematical Institute, University of Oxford, Oxford OX2 6GG, United Kingdom
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10
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11
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Zhao Q, Zhu J, Li N, Wang X, Zhao X, Zhang X. Cryptochrome-mediated hypocotyl phototropism was regulated antagonistically by gibberellic acid and sucrose in Arabidopsis. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2020; 62:614-630. [PMID: 30941890 PMCID: PMC7318699 DOI: 10.1111/jipb.12813] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 03/27/2019] [Indexed: 05/03/2023]
Abstract
Both phototropins (phot1 and phot2) and cryptochromes (cry1 and cry2) were proven as the Arabidopsis thaliana blue light receptors. Phototropins predominately function in photomovement, and cryptochromes play a role in photomorphogenesis. Although cryptochromes have been proposed to serve as positive modulators of phototropic responses, the underlying mechanism remains unknown. Here, we report that depleting sucrose from the medium or adding gibberellic acids (GAs) can partially restore the defects in phototropic curvature of the phot1 phot2 double mutants under high-intensity blue light; this restoration does not occur in phot1 phot2 cry1 cry2 quadruple mutants and nph3 (nonphototropic hypocotyl 3) mutants which were impaired phototropic response in sucrose-containing medium. These results indicate that GAs and sucrose antagonistically regulate hypocotyl phototropism in a cryptochromes dependent manner, but it showed a crosstalk with phototropin signaling on NPH3. Furthermore, cryptochromes activation by blue light inhibit GAs synthesis, thus stabilizing DELLAs to block hypocotyl growth, which result in the higher GAs content in the shade side than the lit side of hypocotyl to support the asymmetric growth of hypocotyl. Through modulation of the abundance of DELLAs by sucrose depletion or added GAs, it revealed that cryptochromes have a function in mediating phototropic curvature.
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Affiliation(s)
- Qing‐Ping Zhao
- Key laboratory of Plant Stress BiologyState Key Laboratory of Cotton BiologySchool of Life SciencesHenan UniversityKaifeng475004China
| | - Jin‐Dong Zhu
- Key laboratory of Plant Stress BiologyState Key Laboratory of Cotton BiologySchool of Life SciencesHenan UniversityKaifeng475004China
| | - Nan‐Nan Li
- Key laboratory of Plant Stress BiologyState Key Laboratory of Cotton BiologySchool of Life SciencesHenan UniversityKaifeng475004China
| | - Xiao‐Nan Wang
- Key laboratory of Plant Stress BiologyState Key Laboratory of Cotton BiologySchool of Life SciencesHenan UniversityKaifeng475004China
| | - Xiang Zhao
- Key laboratory of Plant Stress BiologyState Key Laboratory of Cotton BiologySchool of Life SciencesHenan UniversityKaifeng475004China
| | - Xiao Zhang
- Key laboratory of Plant Stress BiologyState Key Laboratory of Cotton BiologySchool of Life SciencesHenan UniversityKaifeng475004China
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12
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Wang X, Yu R, Wang J, Lin Z, Han X, Deng Z, Fan L, He H, Deng XW, Chen H. The Asymmetric Expression of SAUR Genes Mediated by ARF7/19 Promotes the Gravitropism and Phototropism of Plant Hypocotyls. Cell Rep 2020; 31:107529. [PMID: 32320660 DOI: 10.1016/j.celrep.2020.107529] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 01/21/2020] [Accepted: 03/27/2020] [Indexed: 10/24/2022] Open
Abstract
The asymmetric distribution of auxin leads to the bending growth of hypocotyls during gravitropic and phototropic responses, but the signaling events downstream of auxin remain unclear. Here, we identify many SAUR genes showing asymmetric expression in soybean hypocotyls during gravistimulation and then study their homologs in Arabidopsis. SAUR19 subfamily genes have asymmetric expression in Arabidopsis hypocotyls during gravitropic and phototropic responses, induced by the lateral redistribution of auxin. Both the mutation of SAUR19 subfamily genes and the ectopic expression of SAUR19 weaken these tropic responses, indicating the critical role of their asymmetric expression. The auxin-responsive transcription factor ARF7 may directly bind the SAUR19 promoter and activate SAUR19 expression asymmetrically in tropic responses. Taken together, our results reveal that a gravity- or light-triggered asymmetric auxin distribution induces the asymmetric expression of SAUR19 subfamily genes by ARF7 and ARF19 in the hypocotyls, which leads to bending growth during gravitropic and phototropic responses.
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Affiliation(s)
- Xiaoyi Wang
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Renbo Yu
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Jiajun Wang
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Zechuan Lin
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Xue Han
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Zhaoguo Deng
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Liumin Fan
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Hang He
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Xing Wang Deng
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Haodong Chen
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China.
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13
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Miyazawa Y, Takahashi H. Molecular mechanisms mediating root hydrotropism: what we have observed since the rediscovery of hydrotropism. JOURNAL OF PLANT RESEARCH 2020; 133:3-14. [PMID: 31797131 PMCID: PMC7082378 DOI: 10.1007/s10265-019-01153-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 11/19/2019] [Indexed: 06/02/2023]
Abstract
Roots display directional growth toward moisture in response to a water potential gradient. Root hydrotropism is thought to facilitate plant adaptation to continuously changing water availability. Hydrotropism has not been as extensively studied as gravitropism. However, comparisons of hydrotropic and gravitropic responses identified mechanisms that are unique to hydrotropism. Regulatory mechanisms underlying the hydrotropic response appear to differ among different species. We recently performed molecular and genetic analyses of root hydrotropism in Arabidopsis thaliana. In this review, we summarize the current knowledge of specific mechanisms mediating root hydrotropism in several plant species.
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Affiliation(s)
- Yutaka Miyazawa
- Faculty of Science, Yamagata University, 1-4-12 Kojirakawa-machi, Yamagata, 990-8560, Japan.
| | - Hideyuki Takahashi
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
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14
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Meier MC, Cheng WH, Atwater HA, Lewis NS, Carim AI. Inorganic Phototropism in Electrodeposition of Se-Te. J Am Chem Soc 2019; 141:18658-18661. [PMID: 31697074 DOI: 10.1021/jacs.9b10579] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photoelectrochemical deposition of Se-Te on isolated Au islands using an unstructured, incoherent beam of light produces growth of Se-Te alloy toward the direction of the incident light beam. Full-wave electromagnetic simulations of light absorption indicated that the induced spatial growth anisotropy was a function of asymmetric absorption in the evolving deposit. Inorganic phototropic growth is analogous to biological systems such as palm trees that exhibit phototropic growth wherein physical extension of the plant guides the crown toward the time-averaged position of the sun, to maximize solar harvesting.
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15
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van Wyk AS, Prinsloo G. Challenging current interpretation of sunflower movements. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:6049-6056. [PMID: 31504705 DOI: 10.1093/jxb/erz381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 08/14/2019] [Indexed: 06/10/2023]
Abstract
In the literature, Helianthus annuus L. (sunflower) movements are generally described as heliotropic. It is generally believed that the leaves and flowers of the growing H. annuus plant track the sun as the sun moves across the sky from east to west. This paper, however, challenges current interpretation regarding H. annuus movements, as the literature generally excludes the rotation of the earth around its own axis, gravity, and the possible role of gravitation. The general exclusion of the earth's rotation in the literature may also have resulted in flawed research design in studies conducted on H. annuus movements, which in turn may have directed researchers towards the misinterpretation of results. This paper aims to include the possible role of the Earth's rotation, gravity, and gravitation when describing H. annuus movements and to provide possible alternative explanations for the results achieved by researchers. This paper further includes concepts and examples relevant to plant movements, such as the rhythms often associated with plant movements, the physiology of plant movements, referring to turgor pressure as the main force behind plant movements, and plant rhythmic clocks and their characteristics, in order to explain the alternative views and to relate them to H. annuus movements.
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Affiliation(s)
- Anne S van Wyk
- Department of Environmental Sciences, University of South Africa, Florida campus, Florida, South Africa
| | - Gerhard Prinsloo
- Department of Agriculture and Animal Health, University of South Africa, Florida campus, Florida, South Africa
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16
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Suzuki H, Koshiba T, Fujita C, Yamauchi Y, Kimura T, Isobe T, Sakai T, Taoka M, Okamoto T. Low-fluence blue light-induced phosphorylation of Zmphot1 mediates the first positive phototropism. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:5929-5941. [PMID: 31376280 PMCID: PMC6812725 DOI: 10.1093/jxb/erz344] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 07/25/2019] [Indexed: 05/05/2023]
Abstract
Phototropin1 (phot1) perceives low- to high-fluence blue light stimuli and mediates both the first and second positive phototropisms. High-fluence blue light is known to induce autophosphorylation of phot1, leading to the second positive phototropism. However, the phosphorylation status of phot1 by low-fluence blue light that induces the first positive phototropism had not been observed. Here, we conducted a phosphoproteomic analysis of maize coleoptiles to investigate the fluence-dependent phosphorylation status of Zmphot1. High-fluence blue light induced phosphorylation of Zmphot1 at several sites. Notably, low-fluence blue light significantly increased the phosphorylation level of Ser291 in Zmphot1. Furthermore, Ser291-phosphorylated and Ser369Ser376-diphosphorylated peptides were found to be more abundant in the low-fluence blue light-irradiated sides than in the shaded sides of coleoptiles. The roles of these phosphorylation events in phototropism were explored by heterologous expression of ZmPHOT1 in the Arabidopsis thaliana phot1phot2 mutant. The first positive phototropism was restored in wild-type ZmPHOT1-expressing plants; however, plants expressing S291A-ZmPHOT1 or S369AS376A-ZmPHOT1 showed significantly reduced complementation rates. All transgenic plants tested in this study exhibited a normal second positive phototropism. These findings provide the first indication that low-fluence blue light induces phosphorylation of Zmphot1 and that this induced phosphorylation is crucial for the first positive phototropism.
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Affiliation(s)
- Hiromi Suzuki
- Department of Biological Sciences, Tokyo Metropolitan University, Hachioji-shi, Tokyo, Japan
- Japan Society for the Promotion of Science, Kojimachi Business Center Building, Chiyoda-ku, Tokyo, Japan
- Correspondence: or
| | - Tomokazu Koshiba
- Department of Biological Sciences, Tokyo Metropolitan University, Hachioji-shi, Tokyo, Japan
| | - Chiharu Fujita
- Department of Chemistry, Tokyo Metropolitan University, Hachioji-shi, Tokyo, Japan
| | - Yoshio Yamauchi
- Department of Chemistry, Tokyo Metropolitan University, Hachioji-shi, Tokyo, Japan
| | - Taro Kimura
- Japan Society for the Promotion of Science, Kojimachi Business Center Building, Chiyoda-ku, Tokyo, Japan
- Graduate School of Science and Technology, Niigata University, Niigata-shi, Niigata, Japan
| | - Toshiaki Isobe
- Department of Chemistry, Tokyo Metropolitan University, Hachioji-shi, Tokyo, Japan
| | - Tatsuya Sakai
- Graduate School of Science and Technology, Niigata University, Niigata-shi, Niigata, Japan
| | - Masato Taoka
- Department of Chemistry, Tokyo Metropolitan University, Hachioji-shi, Tokyo, Japan
| | - Takashi Okamoto
- Department of Biological Sciences, Tokyo Metropolitan University, Hachioji-shi, Tokyo, Japan
- Correspondence: or
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17
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Vanhaelewyn L, Viczián A, Prinsen E, Bernula P, Serrano AM, Arana MV, Ballaré CL, Nagy F, Van Der Straeten D, Vandenbussche F. Differential UVR8 Signal across the Stem Controls UV-B-Induced Inflorescence Phototropism. THE PLANT CELL 2019; 31:2070-2088. [PMID: 31289115 PMCID: PMC6751110 DOI: 10.1105/tpc.18.00929] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 05/28/2019] [Accepted: 06/25/2019] [Indexed: 05/10/2023]
Abstract
In the course of evolution, plants have developed mechanisms that orient their organs toward the incoming light. At the seedling stage, positive phototropism is mainly regulated by phototropin photoreceptors in blue and UV wavelengths. Contrasting with this, we report that UV RESISTANCE LOCUS8 (UVR8) serves as the predominant photoreceptor of UV-B-induced phototropic responses in Arabidopsis (Arabidopsis thaliana) inflorescence stems. We examined the molecular mechanisms underlying this response and our findings support the Blaauw theory (Blaauw, 1919), suggesting rapid differential growth through unilateral photomorphogenic growth inhibition. UVR8-dependent UV-B light perception occurs mainly in the epidermis and cortex, but deeper tissues such as endodermis can also contribute. Within stems, a spatial difference of UVR8 signal causes a transcript and protein increase of transcription factors ELONGATED HYPOCOTYL5 (HY5) and its homolog HY5 HOMOLOG at the UV-B-exposed side. The irradiated side shows (1) strong activation of flavonoid synthesis genes and flavonoid accumulation; (2) increased gibberellin (GA)2-oxidase expression, diminished GA1 levels, and accumulation of the DELLA protein REPRESSOR OF GA1; and (3) increased expression of the auxin transport regulator PINOID, contributing to diminished auxin signaling. Together, the data suggest a mechanism of phototropin-independent inflorescence phototropism through multiple, locally UVR8-regulated hormone pathways.
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Affiliation(s)
- Lucas Vanhaelewyn
- Laboratory of Functional Plant Biology, Department of Biology, Faculty of Sciences, Ghent University, KL Ledeganckstraat 35, B-9000 Gent, Belgium
| | - András Viczián
- Institute of Plant Biology, Biological Research Centre, Temesvári körút 62, H-6726 Szeged, Hungary
| | - Els Prinsen
- Department of Biology, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium
| | - Péter Bernula
- Institute of Plant Biology, Biological Research Centre, Temesvári körút 62, H-6726 Szeged, Hungary
- Doctoral School in Biology, Faculty of Science and Informatics, University of Szeged, Szeged, H-6726, Hungary
| | - Alejandro Miguel Serrano
- IADIZA, Av. Ruiz Leal s/n Parque Gral. San Martín, Casilla de Correo 507, Mendoza, 5500, Argentina (CONICET)
| | - Maria Veronica Arana
- Instituto de Investigaciones Forestales y Agropecuarias Bariloche, (CONICET-INTA), Modesta Victoria 4450, San Carlos de Bariloche Rio Negro R8403DVZ, Argentina
| | - Carlos L Ballaré
- IFEVA Universidad de Buenos Aires, Av. San Martín 4453, C1417DSE, Buenos Aires, Argentina
- IIBIO-INTECH, Universidad Nacional de San Martín, B1650HMP, Buenos Aires, Argentina
| | - Ferenc Nagy
- Institute of Plant Biology, Biological Research Centre, Temesvári körút 62, H-6726 Szeged, Hungary
| | - Dominique Van Der Straeten
- Laboratory of Functional Plant Biology, Department of Biology, Faculty of Sciences, Ghent University, KL Ledeganckstraat 35, B-9000 Gent, Belgium
| | - Filip Vandenbussche
- Laboratory of Functional Plant Biology, Department of Biology, Faculty of Sciences, Ghent University, KL Ledeganckstraat 35, B-9000 Gent, Belgium
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18
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Hayes S. Why Do Leaves Rise with the Temperature? PLANT PHYSIOLOGY 2019; 180:691-692. [PMID: 31160521 PMCID: PMC6548270 DOI: 10.1104/pp.19.00446] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 04/15/2019] [Indexed: 06/09/2023]
Affiliation(s)
- Scott Hayes
- Centro Nacional de Bíotecnologia-Consejo Superior de Investigaciones Científicas (CNB-CSIC), 28049 Madrid, Spain
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19
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Vanhaelewyn L, Van Der Straeten D, Vandenbussche F. Determination of Phototropism by UV-B Radiation. Methods Mol Biol 2019; 1924:131-139. [PMID: 30694471 DOI: 10.1007/978-1-4939-9015-3_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
UV-B phototropism in etiolated Arabidopsis seedlings has only been shown recently and needs further exploration. Here we elaborate on how to generate a customized setup with a unilateral UV-B light source, the required plant materials, different growth substrates, and a framework for data analysis.
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Affiliation(s)
- Lucas Vanhaelewyn
- Laboratory of Functional Plant Biology, Department of Biology, Ghent University, Gent, Belgium
| | | | - Filip Vandenbussche
- Laboratory of Functional Plant Biology, Department of Biology, Ghent University, Gent, Belgium.
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20
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Michmizos D, Hilioti Z. A roadmap towards a functional paradigm for learning & memory in plants. JOURNAL OF PLANT PHYSIOLOGY 2019; 232:209-215. [PMID: 30537608 DOI: 10.1016/j.jplph.2018.11.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Revised: 10/15/2018] [Accepted: 11/02/2018] [Indexed: 06/09/2023]
Abstract
In plants, the acquisition, processing and storage of empirical information can result in the modification of their behavior according to the nature of the stimulus, and yet this area of research remained relatively understudied until recently. As the body of evidence supporting the inclusion of plants among the higher organisms demonstrating the adaptations to accomplish these tasks keeps increasing, the resistance by traditional botanists and agricultural scientists, who were at first cautious in allowing the application of animal models onto plant physiology and development, subsides. However, the debate retains much of its heat, a good part of it originating from the controversial use of nervous system terms to describe plant processes. By focusing on the latest findings on the cellular and molecular mechanisms underlying the well established processes of Learning and Memory, recognizing what has been accomplished and what remains to be explored, and without seeking to bootstrap neuronal characteristics where none are to be found, a roadmap guiding towards a comprehensive paradigm for Learning and Memory in plants begins to emerge. Meanwhile the applications of the new field of Plant Gnosophysiology look as promising as ever.
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Affiliation(s)
- Dimitrios Michmizos
- Dept. of Agriculture, Crop Production & Rural Environment, University of Thessaly, Fytokos st, Volos, Magnesia, 384 46, Greece.
| | - Zoe Hilioti
- Institute of Applied Biosciences, Center for Research & Technology (CERTH), Thessaloniki, Greece
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21
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Muthert LWF, Izzo LG, van Zanten M, Aronne G. Root Tropisms: Investigations on Earth and in Space to Unravel Plant Growth Direction. FRONTIERS IN PLANT SCIENCE 2019; 10:1807. [PMID: 32153599 PMCID: PMC7047216 DOI: 10.3389/fpls.2019.01807] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 12/24/2019] [Indexed: 05/12/2023]
Abstract
Root tropisms are important responses of plants, allowing them to adapt their growth direction. Research on plant tropisms is indispensable for future space programs that envisage plant-based life support systems for long-term missions and planet colonization. Root tropisms encompass responses toward or away from different environmental stimuli, with an underexplored level of mechanistic divergence. Research into signaling events that coordinate tropistic responses is complicated by the consistent coincidence of various environmental stimuli, often interacting via shared signaling mechanisms. On Earth the major determinant of root growth direction is the gravitational vector, acting through gravitropism and overruling most other tropistic responses to environmental stimuli. Critical advancements in the understanding of root tropisms have been achieved nullifying the gravitropic dominance with experiments performed in the microgravity environment. In this review, we summarize current knowledge on root tropisms to different environmental stimuli. We highlight that the term tropism must be used with care, because it can be easily confused with a change in root growth direction due to asymmetrical damage to the root, as can occur in apparent chemotropism, electrotropism, and magnetotropism. Clearly, the use of Arabidopsis thaliana as a model for tropism research contributed much to our understanding of the underlying regulatory processes and signaling events. However, pronounced differences in tropisms exist among species, and we argue that these should be further investigated to get a more comprehensive view of the signaling pathways and sensors. Finally, we point out that the Cholodny-Went theory of asymmetric auxin distribution remains to be the central and unifying tropistic mechanism after 100 years. Nevertheless, it becomes increasingly clear that the theory is not applicable to all root tropistic responses, and we propose further research to unravel commonalities and differences in the molecular and physiological processes orchestrating root tropisms.
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Affiliation(s)
| | - Luigi Gennaro Izzo
- Department of Agricultural Sciences, University of Naples Federico II, Naples, Italy
- *Correspondence: Luigi Gennaro Izzo,
| | - Martijn van Zanten
- Molecular Plant Physiology, Institute of Environmental Biology, Utrecht University, Utrecht, Netherlands
| | - Giovanna Aronne
- Department of Agricultural Sciences, University of Naples Federico II, Naples, Italy
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22
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Abstract
To date, many mutants have been isolated from dicot plants, including Arabidopsis thaliana, and the physiological roles of the isolated genes have been identified. Molecular genetic analyses have usually been conducted in the model plant Arabidopsis to identify blue-light photoreceptors and key signaling components in phototropic responses. Despite these investigations, several molecular mechanisms involved in phototropism remain unknown, possibly because detailed physiological analyses have not been conducted properly in the isolated mutants. This chapter describes an approach for the detailed investigation of hypocotyl and root phototropism in Arabidopsis seedlings. The information provided here is expected to facilitate the analysis of phototropic responses in other plant species.
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Affiliation(s)
- Ken Haga
- Department of Applied Chemistry, Faculty of Fundamental Engineering, Nippon Institute of Technology, Miyashiro, Saitama, Japan.
| | - Taro Kimura
- Graduate School of Science and Technology, Niigata University, Niigata, Japan
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23
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Haga K, Frank L, Kimura T, Schwechheimer C, Sakai T. Roles of AGCVIII Kinases in the Hypocotyl Phototropism of Arabidopsis Seedlings. PLANT & CELL PHYSIOLOGY 2018; 59:1060-1071. [PMID: 29490064 DOI: 10.1093/pcp/pcy048] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 02/22/2018] [Indexed: 06/08/2023]
Abstract
Regulation of protein function by phosphorylation and dephosphorylation is an important mechanism in many cellular events. The phototropin blue-light photoreceptors, plant-specific AGCVIII kinases, are essential for phototropic responses. Members of the D6 PROTEIN KINASE (D6PK) family, representing a subfamily of the AGCVIII kinases, also contribute to phototropic responses, suggesting that possibly further AGCVIII kinases may potentially control phototropism. The present study investigates the functional roles of Arabidopsis (Arabidopsis thaliana) AGCVIII kinases in hypocotyl phototropism. We demonstrate that D6PK family kinases are not only required for the second but also for the first positive phototropism. In addition, we find that a previously uncharacterized AGCVIII protein, AGC1-12, is involved in the first positive phototropism and gravitropism. AGC1-12 phosphorylates serine residues in the cytoplasmic loop of PIN-FORMED 1 (PIN1) and shares phosphosite preferences with D6PK. Our work strongly suggests that the D6PK family and AGC1-12 are critical components for both hypocotyl phototropism and gravitropism, and that these kinases control tropic responses mainly through regulation of PIN-mediated auxin transport by protein phosphorylation.
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Affiliation(s)
- Ken Haga
- Department of Human Science and Common Education, Nippon Institute of Technology, 4-1 Gakuendai, Miyashiro-cho, Minamisaitama-gun, Saitama, 345-8501 Japan
| | - Lena Frank
- Plant Systems Biology, Technische Universität München, Emil-Ramann-Strasse 8, D-85354 Freising-Weihenstephan, Germany
| | - Taro Kimura
- Graduate School of Science and Technology, Niigata University, 8050 Ikarashi 2-no-cho, Nishi-ku, Niigata, 950-2181 Japan
- Research Fellow of the Japan Society for the Promotion of Science, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo, 102-0083 Japan
| | - Claus Schwechheimer
- Plant Systems Biology, Technische Universität München, Emil-Ramann-Strasse 8, D-85354 Freising-Weihenstephan, Germany
| | - Tatsuya Sakai
- Graduate School of Science and Technology, Niigata University, 8050 Ikarashi 2-no-cho, Nishi-ku, Niigata, 950-2181 Japan
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24
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Erland LAE, Saxena PK, Murch SJ. Melatonin in plant signalling and behaviour. FUNCTIONAL PLANT BIOLOGY : FPB 2018; 45:58-69. [PMID: 32291021 DOI: 10.1071/fp16384] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 01/29/2017] [Indexed: 05/23/2023]
Abstract
Melatonin is an indoleamine neurotransmitter that has recently become well established as an important multi-functional signalling molecule in plants. These signals have been found to induce several important physiological responses that may be interpreted as behaviours. The diverse processes in which melatonin has been implicated in plants have expanded far beyond the traditional roles for which it has been implicated in mammals, which include sleep, tropisms and reproduction. These functions, however, appear to also be important melatonin mediated processes in plants, though the mechanisms underlying these functions have yet to be fully elucidated. Mediation or redirection of plant physiological processes induced by melatonin can be summarised as a series of behaviours including, among others: herbivore defence, avoidance of undesirable circumstances or attraction to opportune conditions, problem solving and response to environmental stimulus. As the mechanisms of melatonin action are elucidated, its involvement in plant growth, development and behaviour is likely to expand beyond the aspects discussed in this review and hold promise for applications in diverse fundamental and applied plant sciences including conservation, cryopreservation, morphogenesis, industrial agriculture and natural health products.
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Affiliation(s)
- Lauren A E Erland
- Gosling Research Institute for Plant Preservation, Department of Plant Agriculture, University of Guelph, 50 Stone Road E, Guelph, Ontario, N1G 2W1, Canada
| | - Praveen K Saxena
- Gosling Research Institute for Plant Preservation, Department of Plant Agriculture, University of Guelph, 50 Stone Road E, Guelph, Ontario, N1G 2W1, Canada
| | - Susan J Murch
- Chemistry, University of British Columbia, Okanagan, Kelowna, British Columbia, V1V 1V7, Canada
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25
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Nayak AR, McFarland MN, Sullivan JM, Twardowski MS. Evidence for ubiquitous preferential particle orientation in representative oceanic shear flows. LIMNOLOGY AND OCEANOGRAPHY 2018; 63:122-143. [PMID: 29456268 PMCID: PMC5812062 DOI: 10.1002/lno.10618] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 04/10/2017] [Accepted: 05/26/2017] [Indexed: 05/20/2023]
Abstract
In situ measurements were undertaken to characterize particle fields in undisturbed oceanic environments. Simultaneous, co-located depth profiles of particle fields and flow characteristics were recorded using a submersible holographic imaging system and an acoustic Doppler velocimeter, under different flow conditions and varying particle concentration loads, typical of those found in coastal oceans and lakes. Nearly one million particles with major axis lengths ranging from ∼14 μm to 11.6 mm, representing diverse shapes, sizes, and aspect ratios were characterized as part of this study. The particle field consisted of marine snow, detrital matter, and phytoplankton, including colonial diatoms, which sometimes formed "thin layers" of high particle abundance. Clear evidence of preferential alignment of particles was seen at all sampling stations, where the orientation probability density function (PDF) peaked at near horizontal angles and coincided with regions of low velocity shear and weak turbulent dissipation rates. Furthermore, PDF values increased with increasing particle aspect ratios, in excellent agreement with models of spheroidal particle motion in simple shear flows. To the best of our knowledge, although preferential particle orientation in the ocean has been reported in two prior cases, our findings represent the first comprehensive field study examining this phenomenon. Evidence of nonrandom particle alignment in aquatic systems has significant consequences to aquatic optics theory and remote sensing, where perfectly random particle orientation and thus isotropic symmetry in optical parameters is assumed. Ecologically, chain-forming phytoplankton may have evolved to form large aspect ratio chains as a strategy to optimize light harvesting.
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Affiliation(s)
- Aditya R. Nayak
- Harbor Branch Oceanographic Institute at Florida Atlantic UniversityFort PierceFlorida
| | - Malcolm N. McFarland
- Harbor Branch Oceanographic Institute at Florida Atlantic UniversityFort PierceFlorida
| | - James M. Sullivan
- Harbor Branch Oceanographic Institute at Florida Atlantic UniversityFort PierceFlorida
| | - Michael S. Twardowski
- Harbor Branch Oceanographic Institute at Florida Atlantic UniversityFort PierceFlorida
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26
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Abstract
The study on aerial plant organs (leaves and stems) motions is reviewed. The history of observations and studies is put in the perspective of the ideas surrounding them, leading to a presentation of the current classification of these motions. After showing the shortcomings of such a classification, we present, following an idea of Darwin's, the various movements in a renewed and observation-based perspective of the plant development. With this perspective, the different movements fit together logically, and in particular we point out that the mature reversible movements, such as the sensitive or circadian movements, are just partial regressions of the developmental ones.
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Affiliation(s)
- Mathieu Rivière
- Laboratoire Matière & Systèmes Complexes UMR 7057, Université Paris Diderot, Sorbonne Paris Cité, CNRS, F-75205 Paris Cedex 13, France
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27
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Abstract
Intelligence is defined for wild plants and its role in fitness identified. Intelligent behaviour exhibited by single cells and systems similarity between the interactome and connectome indicates neural systems are not necessary for intelligent capabilities. Plants sense and respond to many environmental signals that are assessed to competitively optimize acquisition of patchily distributed resources. Situations of choice engender motivational states in goal-directed plant behaviour; consequent intelligent decisions enable efficient gain of energy over expenditure. Comparison of swarm intelligence and plant behaviour indicates the origins of plant intelligence lie in complex communication and is exemplified by cambial control of branch function. Error correction in behaviours indicates both awareness and intention as does the ability to count to five. Volatile organic compounds are used as signals in numerous plant interactions. Being complex in composition and often species and individual specific, they may represent the plant language and account for self and alien recognition between individual plants. Game theory has been used to understand competitive and cooperative interactions between plants and microbes. Some unexpected cooperative behaviour between individuals and potential aliens has emerged. Behaviour profiting from experience, another simple definition of intelligence, requires both learning and memory and is indicated in the priming of herbivory, disease and abiotic stresses.
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Affiliation(s)
- Anthony Trewavas
- Institute of Plant Molecular Science, University of Edinburgh, Kings Buildings, Edinburgh EH9 3JH, Scotland
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28
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Abstract
Intelligence is defined for wild plants and its role in fitness identified. Intelligent behaviour exhibited by single cells and systems similarity between the interactome and connectome indicates neural systems are not necessary for intelligent capabilities. Plants sense and respond to many environmental signals that are assessed to competitively optimize acquisition of patchily distributed resources. Situations of choice engender motivational states in goal-directed plant behaviour; consequent intelligent decisions enable efficient gain of energy over expenditure. Comparison of swarm intelligence and plant behaviour indicates the origins of plant intelligence lie in complex communication and is exemplified by cambial control of branch function. Error correction in behaviours indicates both awareness and intention as does the ability to count to five. Volatile organic compounds are used as signals in numerous plant interactions. Being complex in composition and often species and individual specific, they may represent the plant language and account for self and alien recognition between individual plants. Game theory has been used to understand competitive and cooperative interactions between plants and microbes. Some unexpected cooperative behaviour between individuals and potential aliens has emerged. Behaviour profiting from experience, another simple definition of intelligence, requires both learning and memory and is indicated in the priming of herbivory, disease and abiotic stresses.
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Affiliation(s)
- Anthony Trewavas
- Institute of Plant Molecular Science, University of Edinburgh, Kings Buildings, Edinburgh EH9 3JH, Scotland
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29
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Ojalehto BL, Medin DL, García SG. Conceptualizing agency: Folkpsychological and folkcommunicative perspectives on plants. Cognition 2017; 162:103-123. [PMID: 28219035 DOI: 10.1016/j.cognition.2017.01.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 01/28/2017] [Accepted: 01/31/2017] [Indexed: 01/15/2023]
Abstract
The present research addresses cultural variation in concepts of agency. Across two experiments, we investigate how Indigenous Ngöbe of Panama and US college students interpret and make inferences about nonhuman agency, focusing on plants as a critical test case. In Experiment 1, participants predicted goal-directed actions for plants and other nonhuman kinds and judged their capacities for intentional agency. Goal-directed action is pervasive among living kinds and as such we expected cultural agreement on these predictions. However, we expected that interpretation of the capacities involved would differ based on cultural folktheories. As expected, Ngöbe and US participants both inferred that plants would engage in goal-directed action but Ngöbe were more likely to attribute intentional agency capacities to plants. Experiment 2 extends these findings by investigating action predictions and capacity attributions linked to complex forms of plant social agency recently discovered in botanical sciences (communication, kin altruism). We hypothesized that the Ngöbe view of plants as active agents would productively guide inferences for plant social interaction. Indeed, Ngöbe were more likely than US participants to infer that plants can engage in social behaviors and they also attributed more social agency capacities to plants. We consolidate these findings by using bottom-up consensus modeling to show that these cultural differences reflect two distinct conceptual models of agency rather than variations on a single (universal) model. We consider these findings in light of current theories of domain-specificity and animism, and offer an alternative account based on a folktheory of communication that infers agency on the basis of relational interactions rather than having a mind.
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Affiliation(s)
- Bethany L Ojalehto
- Psychology Department, Northwestern University, 2029 Sheridan Road - 102 Swift Hall, Evanston, IL 60208-2710, United States.
| | - Douglas L Medin
- Psychology Department, Northwestern University, 2029 Sheridan Road - 102 Swift Hall, Evanston, IL 60208-2710, United States
| | - Salino G García
- Ngöbe Culture and Language Education Program, Bocas del Toro, Panama
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30
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Hu W, Fagundez S, Katin-Grazzini L, Li Y, Li W, Chen Y, Wang X, Deng Z, Xie S, McAvoy RJ, Li Y. Endogenous auxin and its manipulation influence in vitro shoot organogenesis of citrus epicotyl explants. HORTICULTURE RESEARCH 2017; 4:17071. [PMID: 29263793 PMCID: PMC5727491 DOI: 10.1038/hortres.2017.71] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Accepted: 11/13/2017] [Indexed: 05/05/2023]
Abstract
Endogenous auxin is an important regulator of in vivo organ development, but its role in in vitro organogenesis is unclear. It has been observed that the basal end of epicotyl cuttings of juvenile citrus seedlings produces fewer shoots than the apical end. Here, we report that elevated endogenous auxin levels in the basal end of citrus epicotyl cuttings are inhibitory for in vitro shoot organogenesis. Using transgenic citrus plants expressing an auxin-inducible GUS reporter gene, we have observed elevated levels of auxin at the basal end of stem cuttings that are mediated by polar auxin transport. Depleting endogenous auxin or blocking polar auxin transport enhances shoot organogenesis. An auxin transport inhibitor, N-1-naphthylphthalamic acid (NPA), can also enhance shoot organogenesis independent of its action on polar auxin transport. Finally, we demonstrate that the promotional effects of depleting endogenous auxin or blocking polar auxin transport on shoot organogenesis are cytokinin-dependent. Our study thus provides meaningful insights into possible roles of endogenous auxin and polar auxin transport, as well as auxin-cytokinin interactions, in in vitro shoot organogenesis. Meanwhile, our results may also provide practical strategies for improving in vitro shoot organogenesis for citrus and many other plant species.
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Affiliation(s)
- Wei Hu
- National Center for Citrus Improvement, Horticulture and Landscape College, Hunan Agricultural University, Changsha 410128, People’s Republic of China
- Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CT 06269, USA
| | - Sabrina Fagundez
- Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CT 06269, USA
| | - Lorenzo Katin-Grazzini
- Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CT 06269, USA
| | - Yanjun Li
- Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CT 06269, USA
| | - Wei Li
- Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CT 06269, USA
| | - Yingnan Chen
- Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CT 06269, USA
| | - Xiaomin Wang
- Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CT 06269, USA
- Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, 210014 Nanjing, People’s Republic of China
| | - Ziniu Deng
- National Center for Citrus Improvement, Horticulture and Landscape College, Hunan Agricultural University, Changsha 410128, People’s Republic of China
- ()
| | - Shenxi Xie
- National Center for Citrus Improvement, Horticulture and Landscape College, Hunan Agricultural University, Changsha 410128, People’s Republic of China
| | - Richard J McAvoy
- Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CT 06269, USA
| | - Yi Li
- National Center for Citrus Improvement, Horticulture and Landscape College, Hunan Agricultural University, Changsha 410128, People’s Republic of China
- Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CT 06269, USA
- ()
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Plant Responses to Brief Touching: A Mechanism for Early Neighbour Detection? PLoS One 2016; 11:e0165742. [PMID: 27828995 PMCID: PMC5102373 DOI: 10.1371/journal.pone.0165742] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 10/17/2016] [Indexed: 12/14/2022] Open
Abstract
In natural habitats plants can be exposed to brief and light contact with neighbouring plants. This mechanical stimulus may represent a cue that induces responses to nearby plants. However, little is known about the effect of touching on plant growth and interaction with insect herbivores. To simulate contact between plants, a soft brush was used to apply light and brief mechanical stimuli to terminal leaves of potato Solanum tuberosum L. The number of non-glandular trichomes on the leaf surface was counted on images made by light microscope while glandular trichomes and pavement cells were counted on images made under scanning electronic microscope. Volatile compounds were identified and quantified using coupled gas chromatography–mass spectrometry (GC-MS). Treated plants changed their pattern of biomass distribution; they had lower stem mass fraction and higher branch and leaf mass fraction than untouched plants. Size, weight and number of tubers were not significantly affected. Touching did not cause trichome damage nor change their total number on touched terminal leaves. However, on primary leaves the number of glandular trichomes and pavement cells was significantly increased. Touching altered the volatile emission of treated plants; they released higher quantities of the sesquiterpenes (E)-β-caryophyllene, germacrene D-4-ol and (E)-nerolidol, and lower quantities of the terpenes (E)-ocimene and linalool, indicating a systemic effect of the treatment. The odour of touched plants was significantly less preferred by the aphids Macrosiphum euphorbiae and Myzus persicae compared to odour of untouched plants. The results suggest that light contact may have a potential role in the detection of neighbouring plants and may affect plant-insect interactions.
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Warren SD, Baggett LS, Warren H. Directional Floral Orientation in Joshua Trees (Yucca brevifolia). WEST N AM NATURALIST 2016. [DOI: 10.3398/064.076.0313] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
| | - L. Scott Baggett
- USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO
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33
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Rockwell NC, Martin SS, Lagarias JC. Identification of Cyanobacteriochromes Detecting Far-Red Light. Biochemistry 2016; 55:3907-19. [DOI: 10.1021/acs.biochem.6b00299] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nathan C. Rockwell
- Department of Molecular and
Cellular Biology, University of California, Davis, California 95616, United States
| | - Shelley S. Martin
- Department of Molecular and
Cellular Biology, University of California, Davis, California 95616, United States
| | - J. Clark Lagarias
- Department of Molecular and
Cellular Biology, University of California, Davis, California 95616, United States
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34
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Armengot L, Marquès-Bueno MM, Jaillais Y. Regulation of polar auxin transport by protein and lipid kinases. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:4015-4037. [PMID: 27242371 PMCID: PMC4968656 DOI: 10.1093/jxb/erw216] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The directional transport of auxin, known as polar auxin transport (PAT), allows asymmetric distribution of this hormone in different cells and tissues. This system creates local auxin maxima, minima, and gradients that are instrumental in both organ initiation and shape determination. As such, PAT is crucial for all aspects of plant development but also for environmental interaction, notably in shaping plant architecture to its environment. Cell to cell auxin transport is mediated by a network of auxin carriers that are regulated at the transcriptional and post-translational levels. Here we review our current knowledge on some aspects of the 'non-genomic' regulation of auxin transport, placing an emphasis on how phosphorylation by protein and lipid kinases controls the polarity, intracellular trafficking, stability, and activity of auxin carriers. We describe the role of several AGC kinases, including PINOID, D6PK, and the blue light photoreceptor phot1, in phosphorylating auxin carriers from the PIN and ABCB families. We also highlight the function of some receptor-like kinases (RLKs) and two-component histidine kinase receptors in PAT, noting that there are probably RLKs involved in co-ordinating auxin distribution yet to be discovered. In addition, we describe the emerging role of phospholipid phosphorylation in polarity establishment and intracellular trafficking of PIN proteins. We outline these various phosphorylation mechanisms in the context of primary and lateral root development, leaf cell shape acquisition, as well as root gravitropism and shoot phototropism.
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Affiliation(s)
- Laia Armengot
- Laboratoire Reproduction et Développement des Plantes, Univ Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, F-69342, Lyon, France
| | - Maria Mar Marquès-Bueno
- Laboratoire Reproduction et Développement des Plantes, Univ Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, F-69342, Lyon, France
| | - Yvon Jaillais
- Laboratoire Reproduction et Développement des Plantes, Univ Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, F-69342, Lyon, France
- Correspondence to:
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35
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Kutschera U, Briggs WR. Phototropic solar tracking in sunflower plants: an integrative perspective. ANNALS OF BOTANY 2016; 117:1-8. [PMID: 26420201 PMCID: PMC4701145 DOI: 10.1093/aob/mcv141] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 07/30/2015] [Indexed: 05/04/2023]
Abstract
BACKGROUND One of the best-known plant movements, phototropic solar tracking in sunflower (Helianthus annuus), has not yet been fully characterized. Two questions are still a matter of debate. (1) Is the adaptive significance solely an optimization of photosynthesis via the exposure of the leaves to the sun? (2) Is shade avoidance involved in this process? In this study, these concepts are discussed from a historical perspective and novel insights are provided. SCOPE AND METHODS Results from the primary literature on heliotropic growth movements led to the conclusion that these responses cease before anthesis, so that the flowering heads point to the East. Based on observations on 10-week-old plants, the diurnal East-West oscillations of the upper fifth of the growing stem and leaves in relation to the position of the sun (inclusive of nocturnal re-orientation) were documented, and photon fluence rates on the leaf surfaces on clear, cloudy and rainy days were determined. In addition, the light-response curve of net CO2 assimilation was determined on the upper leaves of the same batch of plants, and evidence for the occurrence of shade-avoidance responses in growing sunflower plants is summarized. CONCLUSIONS Only elongating, vegetative sunflower shoots and the upper leaves perform phototropic solar tracking. Photon fluence response and CO2 assimilation measurements cast doubt on the 'photosynthesis-optimization hypothesis' as the sole explanation for the evolution of these plant movements. We suggest that the shade-avoidance response, which maximizes light-driven CO2 assimilation, plays a major role in solar tracking populations of competing sunflower plants, and an integrative scheme of these growth movements is provided.
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Affiliation(s)
- Ulrich Kutschera
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Winslow R Briggs
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA
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36
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Novák J, Černý M, Pavlů J, Zemánková J, Skalák J, Plačková L, Brzobohatý B. Roles of proteome dynamics and cytokinin signaling in root to hypocotyl ratio changes induced by shading roots of Arabidopsis seedlings. PLANT & CELL PHYSIOLOGY 2015; 56:1006-18. [PMID: 25700275 DOI: 10.1093/pcp/pcv026] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Indexed: 05/20/2023]
Abstract
In nature, root systems of most terrestrial plants are protected from light exposure by growing in a dark soil environment. Hence, in vitro cultivation in transparent Petri dishes leads to physiological perturbations, but the mechanisms underlying root-mediated light perception and responses have not been fully elucidated. Thus, we compared Arabidopsis thaliana seedling development in transparent and darkened Petri dishes at low light intensity (20 µmol m(-2) s(-1)), allowing us to follow (inter alia) hypocotyl elongation, which is an excellent process for studying interactions of signals involved in the regulation of growth and developmental responses. To obtain insights into molecular events underlying differences in seedling growth under these two conditions, we employed liquid chromatography-mass spectrometry (LC-MS) shotgun proteomics (available via the PRIDE deposit PXD001612). In total, we quantified the relative abundances of peptides representing 1,209 proteins detected in all sample replicates of LC-MS analyses. Comparison of MS spectra after manual validation revealed 48 differentially expressed proteins. Functional classification, analysis of available gene expression data and literature searches revealed alterations associated with root illumination (inter alia) in autotrophic CO2 fixation, C compound and carbohydrate metabolism, and nitrogen metabolism. The results also indicate a previously unreported role for cytokinin plant hormones in the escape-tropism response to root illumination. We complemented these results with reverse transcription followed by quantitative PCR (RT-qPCR), chlorophyll fluorescence and detailed cytokinin signaling analyses, detecting in the latter a significant increase in the activity of the cytokinin two-component signaling cascade in roots and implicating the cytokinin receptor AHK3 as the major mediator of root to hypocotyl signaling in responses to root illumination.
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Affiliation(s)
- Jan Novák
- Laboratory of Plant Molecular Biology, Institute of Biophysics AS CR, v.v.i. and CEITEC-Central European Institute of Technology, Mendel University in Brno, Zemědělská 1, CZ-613 00 Brno, Czech Republic These authors contributed equally to this work
| | - Martin Černý
- Laboratory of Plant Molecular Biology, Institute of Biophysics AS CR, v.v.i. and CEITEC-Central European Institute of Technology, Mendel University in Brno, Zemědělská 1, CZ-613 00 Brno, Czech Republic These authors contributed equally to this work
| | - Jaroslav Pavlů
- Laboratory of Plant Molecular Biology, Institute of Biophysics AS CR, v.v.i. and CEITEC-Central European Institute of Technology, Mendel University in Brno, Zemědělská 1, CZ-613 00 Brno, Czech Republic
| | - Jana Zemánková
- Laboratory of Plant Molecular Biology, Institute of Biophysics AS CR, v.v.i. and CEITEC-Central European Institute of Technology, Mendel University in Brno, Zemědělská 1, CZ-613 00 Brno, Czech Republic
| | - Jan Skalák
- Laboratory of Plant Molecular Biology, Institute of Biophysics AS CR, v.v.i. and CEITEC-Central European Institute of Technology, Mendel University in Brno, Zemědělská 1, CZ-613 00 Brno, Czech Republic
| | - Lenka Plačková
- Laboratory of Growth Regulators & Department of Chemical Biology and Genetics, Centre of the Region Haná for Biotechnological and Agricultural Research, Institute of Experimental Botany AS CR & Faculty of Science of Palacký University, Šlechtitelů 11, CZ-78371 Olomouc, Czech Republic
| | - Břetislav Brzobohatý
- Laboratory of Plant Molecular Biology, Institute of Biophysics AS CR, v.v.i. and CEITEC-Central European Institute of Technology, Mendel University in Brno, Zemědělská 1, CZ-613 00 Brno, Czech Republic
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37
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Preuten T, Blackwood L, Christie JM, Fankhauser C. Lipid anchoring of Arabidopsis phototropin 1 to assess the functional significance of receptor internalization: should I stay or should I go? THE NEW PHYTOLOGIST 2015; 206:1038-1050. [PMID: 25643813 DOI: 10.1111/nph.13299] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 12/16/2014] [Indexed: 05/05/2023]
Abstract
The phototropin 1 (phot1) blue light receptor mediates a number of adaptive responses, including phototropism, that generally serve to optimize photosynthetic capacity. Phot1 is a plasma membrane-associated protein, but upon irradiation, a fraction is internalized into the cytoplasm. Although this phenomenon has been reported for more than a decade, its biological significance remains elusive. Here, we use a genetic approach to revisit the prevalent hypotheses regarding the functional importance of receptor internalization. Transgenic plants expressing lipidated versions of phot1 that are permanently anchored to the plasma membrane were used to analyse the effect of internalization on receptor turnover, phototropism and other phot1-mediated responses. Myristoylation and farnesylation effectively prevented phot1 internalization. Both modified photoreceptors were found to be fully functional in Arabidopsis, rescuing phototropism and all other phot1-mediated responses tested. Light-mediated phot1 turnover occurred as in the native receptor. Furthermore, our work does not provide any evidence of a role of phot1 internalization in the attenuation of receptor signalling during phototropism. Our results demonstrate that phot1 signalling is initiated at the plasma membrane. They furthermore indicate that release of phot1 into the cytosol is not linked to receptor turnover or desensitization.
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Affiliation(s)
- Tobias Preuten
- Centre for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Génopode Building, Lausanne, CH-1015, Switzerland
| | - Lisa Blackwood
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Bower Building, Glasgow, G12 8QQ, UK
| | - John M Christie
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Bower Building, Glasgow, G12 8QQ, UK
| | - Christian Fankhauser
- Centre for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Génopode Building, Lausanne, CH-1015, Switzerland
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38
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Abstract
ATP-driven transport across biological membranes is a key process to translocate solutes from the interior of the cell to the extracellular environment. In humans, ATP-binding cassette transporters are involved in absorption, distribution, metabolism, excretion, and toxicity, and also play a major role in anticancer drug resistance. Analogous transporters are also known to be involved in phytohormone translocation. These include, e.g., the transport of auxin by ABCB1/19 in Arabidopsis thaliana, the transport of abscisic acid by AtABCG25, and the transport of strigolactone by the Petunia hybrida ABC transporter PDR1. Within this article, we outline the current knowledge about plant ABC transporters with respect to their structure and function, and provide, for the first time, a protein homology model of the strigolactone transporter PDR1 from P. hybrida.
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Affiliation(s)
- Eva Hellsberg
- University of Vienna, Department of Pharmaceutical Chemistry, Vienna, Austria
| | - Floriane Montanari
- University of Vienna, Department of Pharmaceutical Chemistry, Vienna, Austria
| | - Gerhard F Ecker
- University of Vienna, Department of Pharmaceutical Chemistry, Vienna, Austria
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39
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Wang R, Wang J, Zhao L, Yang S, Song Y. Impact of heavy metal stresses on the growth and auxin homeostasis of Arabidopsis seedlings. Biometals 2014; 28:123-32. [PMID: 25416404 DOI: 10.1007/s10534-014-9808-6] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Accepted: 11/13/2014] [Indexed: 11/25/2022]
Abstract
The phytohormone auxin is an essential mediator in many aspects of plant development. Its dynamic and differential distribution within the plant is regulated by a variety of environmental cues including heavy metal stimuli. In the present study, we first evaluated the toxic effects of seven heavy metals including Pb(2+), Cd(2+), Hg(2+), Ni(2+). Zn(2+), Co(2+) and Cu(2+) in their excess on the model plant, Arabidopsis thaliana. Various morphological defects including loss in fresh weight and leaf area, decrease of the primary root length and stimulation of the lateral root density occurred to a different extent among seven heavy metals. Next, using an indicative DR5:GUS reporter line of Arabidopsis, the auxin accumulation and distribution within plant seedlings were found to be dramatically and differentially affected by these heavy metals. We further analyzed the transcriptional changes of 27 selected auxin homeostasis-related genes by qRT-PCR technique and found that upon various heavy metals, the expressions of the candidate genes were distinctly altered in shoots and roots. Our data indicated that when confronted with excessive heavy metals, plants could dynamically and differentially regulate the transcription of auxin-related genes to adjust the location and effective accumulation of auxin within the plant for better adaptation and survival under the adverse environment.
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Affiliation(s)
- Rui Wang
- School of Environmental Science and Engineering, Tianjin University, Weijin Road 92, Nankai District, Tianjin, 300072, China
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40
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Haga K, Hayashi KI, Sakai T. PINOID AGC kinases are necessary for phytochrome-mediated enhancement of hypocotyl phototropism in Arabidopsis. PLANT PHYSIOLOGY 2014; 166:1535-45. [PMID: 25281709 PMCID: PMC4226372 DOI: 10.1104/pp.114.244434] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 10/02/2014] [Indexed: 05/18/2023]
Abstract
Several members of the AGCVIII kinase subfamily, which includes PINOID (PID), PID2, and WAVY ROOT GROWTH (WAG) proteins, have previously been shown to phosphorylate PIN-FORMED (PIN) auxin transporters and control the auxin flow in plants. PID has been proposed as a key component of the phototropin signaling pathway that induces phototropic responses, although the responses were not significantly impaired in the pid single and pid wag1 wag2 triple mutants. This raises questions about the functional roles of the PID family in phototropic responses. Here, we investigated hypocotyl phototropism in the pid pid2 wag1 wag2 quadruple mutant in detail to clarify the roles of the PID family in Arabidopsis (Arabidopsis thaliana). The pid quadruple mutants exhibited moderate responses in continuous light-induced phototropism with a decrease in growth rates of hypocotyls and normal responses in pulse-induced phototropism. However, they showed serious defects in enhancements of pulse-induced phototropic curvatures and lateral fluorescent auxin transport by red light pretreatment. Red light pretreatment significantly reduced the expression level of PID, and the constitutive expression of PID prevented pulse-induced phototropism, irrespective of red light pretreatment. This suggests that the PID family plays a significant role in phytochrome-mediated phototropic enhancement but not the phototropin signaling pathway. Red light treatment enhanced the intracellular accumulation of PIN proteins in response to the vesicle-trafficking inhibitor brefeldin A in addition to increasing their expression levels. Taken together, these results suggest that red light preirradiation enhances phototropic curvatures by up-regulation of PIN proteins, which are not being phosphorylated by the PID family.
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Affiliation(s)
- Ken Haga
- Department of Human Science and Common Education, Nippon Institute of Technology, Saitama 345-8501, Japan (K.H.);Department of Biochemistry, Okayama University of Science, Okayama 700-0005, Japan (K.-i.H.); andGraduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan (T.S.)
| | - Ken-ichiro Hayashi
- Department of Human Science and Common Education, Nippon Institute of Technology, Saitama 345-8501, Japan (K.H.);Department of Biochemistry, Okayama University of Science, Okayama 700-0005, Japan (K.-i.H.); andGraduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan (T.S.)
| | - Tatsuya Sakai
- Department of Human Science and Common Education, Nippon Institute of Technology, Saitama 345-8501, Japan (K.H.);Department of Biochemistry, Okayama University of Science, Okayama 700-0005, Japan (K.-i.H.); andGraduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan (T.S.)
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Hohm T, Demarsy E, Quan C, Allenbach Petrolati L, Preuten T, Vernoux T, Bergmann S, Fankhauser C. Plasma membrane H⁺ -ATPase regulation is required for auxin gradient formation preceding phototropic growth. Mol Syst Biol 2014; 10:751. [PMID: 25261457 PMCID: PMC4299663 DOI: 10.15252/msb.20145247] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Phototropism is a growth response allowing plants to align their photosynthetic organs toward
incoming light and thereby to optimize photosynthetic activity. Formation of a lateral gradient of
the phytohormone auxin is a key step to trigger asymmetric growth of the shoot leading to
phototropic reorientation. To identify important regulators of auxin gradient formation, we
developed an auxin flux model that enabled us to test in silico the impact of
different morphological and biophysical parameters on gradient formation, including the contribution
of the extracellular space (cell wall) or apoplast. Our model indicates that cell size, cell
distributions, and apoplast thickness are all important factors affecting gradient formation. Among
all tested variables, regulation of apoplastic pH was the most important to enable the formation of
a lateral auxin gradient. To test this prediction, we interfered with the activity of plasma
membrane H+-ATPases that are required to control apoplastic pH. Our results show
that H+-ATPases are indeed important for the establishment of a lateral auxin
gradient and phototropism. Moreover, we show that during phototropism, H+-ATPase
activity is regulated by the phototropin photoreceptors, providing a mechanism by which light
influences apoplastic pH.
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Affiliation(s)
- Tim Hohm
- Department of Medical Genetics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland Swiss Institute for Bioinformatics, Lausanne, Switzerland
| | - Emilie Demarsy
- Centre for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Clément Quan
- Centre for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Laure Allenbach Petrolati
- Centre for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Tobias Preuten
- Centre for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Teva Vernoux
- Laboratoire de Reproduction et Développement des Plantes, CNRS INRA ENS Lyon UCBL Université de Lyon, Lyon, France
| | - Sven Bergmann
- Department of Medical Genetics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland Swiss Institute for Bioinformatics, Lausanne, Switzerland
| | - Christian Fankhauser
- Centre for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
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Auxin-callose-mediated plasmodesmal gating is essential for tropic auxin gradient formation and signaling. Dev Cell 2014; 28:132-46. [PMID: 24480642 DOI: 10.1016/j.devcel.2013.12.008] [Citation(s) in RCA: 118] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 10/16/2013] [Accepted: 12/10/2013] [Indexed: 01/10/2023]
Abstract
In plants, auxin functions as a master controller of development, pattern formation, morphogenesis, and tropic responses. A sophisticated transport system has evolved to allow the establishment of precise spatiotemporal auxin gradients that regulate specific developmental programs. A critical unresolved question relates to how these gradients can be maintained in the presence of open plasmodesmata that allow for symplasmic exchange of essential nutrients and signaling macromolecules. Here we addressed this conundrum using genetic, physiological, and cell biological approaches and identified the operation of an auxin-GSL8 feedback circuit that regulates the level of plasmodesmal-localized callose in order to locally downregulate symplasmic permeability during hypocotyl tropic response. This system likely involves a plasmodesmal switch that would prevent the dissipation of a forming gradient by auxin diffusion through the symplasm. This regulatory system may represent a mechanism by which auxin could also regulate symplasmic delivery of a wide range of signaling agents.
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Yamamoto K, Suzuki T, Aihara Y, Haga K, Sakai T, Nagatani A. The phototropic response is locally regulated within the topmost light-responsive region of the Arabidopsis thaliana seedling. PLANT & CELL PHYSIOLOGY 2014; 55:497-506. [PMID: 24334375 DOI: 10.1093/pcp/pct184] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Phototropism is caused by differential cell elongation between the irradiated and shaded sides of plant organs, such as the stem. It is widely accepted that an uneven auxin distribution between the two sides crucially participates in this response. Plant-specific blue-light photoreceptors, phototropins (phot1 and phot2), mediate this response. In grass coleoptiles, the sites of light perception and phototropic bending are spatially separated. However, these sites are less clearly distinguished in dicots. Furthermore, the exact placement of the action of each phototropic signaling factor remains unknown. Here, we investigated the spatial aspects of phototropism using spotlight irradiation with etiolated Arabidopsis seedlings. The results demonstrated that the topmost part of about 1.1 mm of the hypocotyl constituted the light-responsive region in which both light perception and actual bending occurred. In addition, cotyledons and the shoot apex were dispensable for the response. Hence, the response was more region autonomous in dicots than in monocots. We next examined the elongation rates, the levels of phot1 and the auxin-reporter gene expression along the hypocotyl during the phototropic response. The light-responsive region was more active than the non-responsive region with respect to all of those parameters.
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Affiliation(s)
- Kazuhiko Yamamoto
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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Zhang KX, Xu HH, Yuan TT, Zhang L, Lu YT. Blue-light-induced PIN3 polarization for root negative phototropic response in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 76:308-21. [PMID: 23888933 DOI: 10.1111/tpj.12298] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 06/04/2013] [Accepted: 07/12/2013] [Indexed: 05/04/2023]
Abstract
Root negative phototropism is an important response in plants. Although blue light is known to mediate this response, the cellular and molecular mechanisms underlying root negative phototropism remain unclear. Here, we report that the auxin efflux carrier PIN-FORMED (PIN) 3 is involved in asymmetric auxin distribution and root negative phototropism. Unilateral blue-light illumination polarized PIN3 to the outer lateral membrane of columella cells at the illuminated root side, and increased auxin activity at the illuminated side of roots, where auxin promotes growth and causes roots bending away from the light source. Furthermore, root negative phototropic response and blue-light-induced PIN3 polarization were modulated by a brefeldin A-sensitive, GNOM-dependent, trafficking pathway and by phot1-regulated PINOID (PID)/PROTEIN PHOSPHATASE 2A (PP2A) activity. Our results indicate that blue-light-induced PIN3 polarization is needed for asymmetric auxin distribution during root negative phototropic response.
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Affiliation(s)
- Kun-Xiao Zhang
- Key Lab of MOE for Plant Development, College of Life Sciences, Wuhan University, Wuhan, 430072, China
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Defining the Site of Light Perception and Initiation of Phototropism in Arabidopsis. Curr Biol 2013; 23:1934-8. [DOI: 10.1016/j.cub.2013.07.079] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 06/26/2013] [Accepted: 07/26/2013] [Indexed: 11/18/2022]
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Goyal A, Szarzynska B, Fankhauser C. Phototropism: at the crossroads of light-signaling pathways. TRENDS IN PLANT SCIENCE 2013; 18:393-401. [PMID: 23562459 DOI: 10.1016/j.tplants.2013.03.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Revised: 02/28/2013] [Accepted: 03/08/2013] [Indexed: 05/11/2023]
Abstract
Phototropism enables plants to orient growth towards the direction of light and thereby maximizes photosynthesis in low-light environments. In angiosperms, blue-light photoreceptors called phototropins are primarily involved in sensing the direction of light. Phytochromes and cryptochromes (sensing red/far-red and blue light, respectively) also modulate asymmetric hypocotyl growth, leading to phototropism. Interactions between different light-signaling pathways regulating phototropism occur in cryptogams and angiosperms. In this review, we focus on the molecular mechanisms underlying the co-action between photosensory systems in the regulation of hypocotyl phototropism in Arabidopsis thaliana. Recent studies have shown that phytochromes and cryptochromes enhance phototropism by controlling the expression of important regulators of phototropin signaling. In addition, phytochromes may also regulate growth towards light via direct interaction with the phototropins.
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Affiliation(s)
- Anupama Goyal
- Centre for Integrative Genomics, University of Lausanne, Genopode Building, CH 1015 Lausanne, Switzerland
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Sun J, Qi L, Li Y, Zhai Q, Li C. PIF4 and PIF5 transcription factors link blue light and auxin to regulate the phototropic response in Arabidopsis. THE PLANT CELL 2013; 25:2102-14. [PMID: 23757399 PMCID: PMC3723615 DOI: 10.1105/tpc.113.112417] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2013] [Revised: 05/13/2013] [Accepted: 05/27/2013] [Indexed: 05/19/2023]
Abstract
Both blue light (BL) and auxin are essential for phototropism in Arabidopsis thaliana. However, the mechanisms by which light is molecularly linked to auxin during phototropism remain elusive. Here, we report that phytochrome interacting factoR4 (PIF4) and PIF5 act downstream of the BL sensor phototropin1 (PHOT1) to negatively modulate phototropism in Arabidopsis. We also reveal that PIF4 and PIF5 negatively regulate auxin signaling. Furthermore, we demonstrate that PIF4 directly activates the expression of the auxin/indole-3-acetic acid (IAA) genes IAA19 and IAA29 by binding to the G-box (CACGTG) motifs in their promoters. Our genetic assays demonstrate that IAA19 and IAA29, which physically interact with auxin response factor7 (ARF7), are sufficient for PIF4 to negatively regulate auxin signaling and phototropism. This study identifies a key step of phototropic signaling in Arabidopsis by showing that PIF4 and PIF5 link light and auxin.
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Christie JM, Murphy AS. Shoot phototropism in higher plants: new light through old concepts. AMERICAN JOURNAL OF BOTANY 2013; 100:35-46. [PMID: 23048016 DOI: 10.3732/ajb.1200340] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Light is a key environmental factor that drives many aspects of plant growth and development. Phototropism, the reorientation of growth toward or away from light, represents one of these important adaptive processes. Modern studies of phototropism began with experiments conducted by Charles Darwin demonstrating that light perception at the shoot apex of grass coleoptiles induces differential elongation in the lower epidermal cells. This led to the discovery of the plant growth hormone auxin and the Cholodny-Went hypothesis attributing differential tropic bending to lateral auxin relocalization. In the past two decades, molecular-genetic analyses in the model flowering plant Arabidopsis thaliana has identified the principal photoreceptors for phototropism and their mechanism of activation. In addition, several protein families of auxin transporters have been identified. Despite extensive efforts, however, it still remains unclear as to how photoreceptor activation regulates lateral auxin transport to establish phototropic growth. This review aims to summarize major developments from over the last century and how these advances shape our current understanding of higher plant phototropism. Recent progress in phototropism research and the way in which this research is shedding new light on old concepts, including the Cholodny-Went hypothesis, is also highlighted.
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Affiliation(s)
- John M Christie
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, G12 8QQ, UK.
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Harada A, Takemiya A, Inoue SI, Sakai T, Shimazaki KI. Role of RPT2 in leaf positioning and flattening and a possible inhibition of phot2 signaling by phot1. PLANT & CELL PHYSIOLOGY 2013; 54:36-47. [PMID: 22739508 DOI: 10.1093/pcp/pcs094] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We investigated the roles of the blue light receptors phototropins (phot1 and phot2) and ROOT PHOTOTROPISM 2 (RPT2) in leaf positioning and flattening, and plant growth under weak, moderate and strong white light (10, 25 and 70 µmol m(-2 )s(-1)). RPT2 mediated leaf positioning and flattening, and enhanced plant growth in a phot1-dependent manner. Under weak light, phot1 alone controls these responses. Under moderate and strong light, both phot1 and phot2 affect the responses. These results indicate that plants utilize a wide range of light intensities through phot1 and phot2 to optimize plant growth. The rpt2 single mutant generally exhibited phenotypes that resembled those of the phot1 phot2 double mutant. To our surprise, when the PHOT1 gene was disrupted in the rpt2 mutant, the resulting phot1 rpt2 double mutant showed the morphology of the wild-type plant under strong light, and additional disruption of PHOT2 in the double mutant abolished this recovery. This suggested that phot2 may function in the absence of phot1 and bypass RPT2 to transmit the signal to downstream elements. Expression and light-induced autophosphorylation of phot2 were not affected in the rpt2 mutant. We conclude that RPT2 mediates leaf flattening and positioning in a phot1-dependent manner, and that phot1 may inhibit the phot2 signaling pathways. We discuss the functional role of RPT2 in phototropin signaling.
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Affiliation(s)
- Akiko Harada
- Department of Biology, Faculty of Liberal Arts, Osaka Medical College, 2-7, Daigaku-machi, Takatsuki 569-8686, Osaka, Japan.
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Hohm T, Preuten T, Fankhauser C. Phototropism: translating light into directional growth. AMERICAN JOURNAL OF BOTANY 2013; 100:47-59. [PMID: 23152332 DOI: 10.3732/ajb.1200299] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Phototropism allows plants to align their photosynthetic tissues with incoming light. The direction of incident light is sensed by the phototropin family of blue light photoreceptors (phot1 and phot2 in Arabidopsis), which are light-activated protein kinases. The kinase activity of phototropins and phosphorylation of residues in the activation loop of their kinase domains are essential for the phototropic response. These initial steps trigger the formation of the auxin gradient across the hypocotyl that leads to asymmetric growth. The molecular events between photoreceptor activation and the growth response are only starting to be elucidated. In this review, we discuss the major steps leading from light perception to directional growth concentrating on Arabidopsis. In addition, we highlight links that connect these different steps enabling the phototropic response.
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Affiliation(s)
- Tim Hohm
- Department of Medical Genetics, Faculty of Biology and Medicine, University of Lausanne, Rue du Bugnon 27, CH-1005 Lausanne, Switzerland
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