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Takata N, Tsuyama T, Nagano S, Baba K, Yasuda Y, Sakamoto S, Mitsuda N, Taniguchi T. Prior secondary cell wall formation is required for gelatinous layer deposition and posture control in gravi-stimulated aspen. Plant J 2021; 108:725-736. [PMID: 34396622 DOI: 10.1111/tpj.15466] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 07/19/2021] [Accepted: 08/10/2021] [Indexed: 06/13/2023]
Abstract
Cell walls, especially secondary cell walls (SCWs), maintain cell shape and reinforce wood, but their structure and shape can be altered in response to gravity. In hardwood trees, tension wood is formed along the upper side of a bending stem and contains wood fiber cells that have a gelatinous layer (G-layer) inside the SCW. In a previous study, we generated nst/snd quadruple-knockout aspens (Populus tremula × Populus tremuloides), in which SCW formation was impaired in 99% of the wood fiber cells. In the present study, we produced nst/snd triple-knockout aspens, in which a large number of wood fibers had thinner SCWs than the wild type (WT) and some had no SCW. Because SCW layers are always formed prior to G-layer deposition, the nst/snd mutants raise interesting questions of whether the mutants can form G-layers without SCW and whether they can control their postures in response to changes in gravitational direction. The nst/snd mutants and the WT plants showed growth eccentricity and vessel frequency reduction when grown on an incline, but the triple mutants recovered their upright growth only slightly, and the quadruple mutants were unable to maintain their postures. The mutants clearly showed that the G-layers were formed in SCW-containing wood fibers but not in those lacking the SCW. Our results indicate that SCWs are essential for G-layer formation and posture control. Furthermore, each wood fiber cell may be able to recognize its cell wall developmental stage to initiate the formation of the G-layer as a response to gravistimulation.
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Affiliation(s)
- Naoki Takata
- Forest Bio-Research Center, Forestry and Forest Products Research Institute, Hitachi, Ibaraki, 319-1301, Japan
| | - Taku Tsuyama
- Faculty of Agriculture, University of Miyazaki, Miyazaki, Miyazaki, 889-2192, Japan
| | - Soichiro Nagano
- Forest Tree Breeding Center, Forestry and Forest Products Research Institute, Forest Research and Management Organization, Hitachi, Ibaraki, 319-1301, Japan
| | - Kei'ichi Baba
- Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Kyoto, 611-0011, Japan
| | - Yuko Yasuda
- Forest Tree Breeding Center, Forestry and Forest Products Research Institute, Forest Research and Management Organization, Hitachi, Ibaraki, 319-1301, Japan
| | - Shingo Sakamoto
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, 305-8566, Japan
- Global Zero Emission Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan
| | - Nobutaka Mitsuda
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, 305-8566, Japan
- Global Zero Emission Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan
| | - Toru Taniguchi
- Forest Bio-Research Center, Forestry and Forest Products Research Institute, Hitachi, Ibaraki, 319-1301, Japan
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Kim ES, Choi W, Park SH. The thickening and modification of the galactan-enriched layer during primary phloem fibre development in Cannabis sativa. AoB Plants 2021; 13:plab044. [PMID: 34394905 PMCID: PMC8356173 DOI: 10.1093/aobpla/plab044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 07/12/2021] [Indexed: 06/13/2023]
Abstract
Primary phloem fibres (PPFs) have higher fibre quality and are economically more important for the textile sector than secondary phloem fibres. Both the chemical composition and mechanical structure of the secondary cell wall mainly influence the quality of bast fibres. We investigated the thickening of the galactan-enriched (Gn) layer and its modification process into a gelatinous (G)-layer, which is the largest portion of the secondary cell wall, during the development of the PPF in Cannabis sativa. Stem segments of hemp collected at 17, 29, 52 and 62 days after sowing were comparatively examined using light microscopy, scanning electron microscopy and transmission electron microscopy. The initial cells of PPF started the proliferation and differentiation at 17 days, but the secondary cell wall thickening had already commenced before the 29 days. Both the G- and Gn-layer were rapidly added onto the S-layer of PPFs; thus, the secondary cell wall thickness increased approximately 2-fold at 52 days (from the 29-day mark), and 8-fold at 62 days. The cortical microtubule arrays appeared adjacent to the plasma membrane of PPF cells related to the cellulose synthesis. Additionally, cross-sectioned microfibrils were observed on Gn-layer as the cluster of tiny spots. At 62 days, the specific stratification structure consisting of several lamellae occurred on the G-layer of the secondary cell wall. The secondary cell wall thickened remarkably at 52 days through 62 days so that the mature secondary cell wall consisted of three distinctive layers, the S-, G- and Gn-layer. Cortical microtubule arrays frequently appeared adjacent to the plasma membrane together with cellulose microfibrils on secondary cell wall. The G-layer of PPF at 62 days exhibited the characteristic stratification structure, which demonstrates the modification of the Gn-layer into the G-layer.
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Affiliation(s)
- Eun-Soo Kim
- Institute of Cannabis Research, Colorado State University-Pueblo, Pueblo, CO 81001-4901, USA
| | - Wonkyun Choi
- Division of Ecological Safety, National Institute of Ecology, Seocheon 33657, South Korea
| | - Sang-Hyuck Park
- Institute of Cannabis Research, Colorado State University-Pueblo, Pueblo, CO 81001-4901, USA
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Jin Y, Yu C, Jiang C, Guo X, Li B, Wang C, Kong F, Zhang H, Wang H. PtiCYP85A3, a BR C-6 Oxidase Gene, Plays a Critical Role in Brassinosteroid-Mediated Tension Wood Formation in Poplar. Front Plant Sci 2020; 11:468. [PMID: 32391036 PMCID: PMC7193022 DOI: 10.3389/fpls.2020.00468] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 03/30/2020] [Indexed: 05/21/2023]
Abstract
In angiosperm trees, the gelatinous layer (G-layer) takes a great part of the fiber cell wall in the tension wood (TW). However, the mechanism underlying G-layer formation in poplar is largely unknown. In this work, we demonstrate that G-layer formation in poplar TW cells is regulated by brassinosteroid (BR) and its signaling. PtiCYP85A3, a key BR biosynthesis gene, was predominantly expressed in the xylem of TW, accompanied with a relatively higher castasterone (CS) accumulation, than in the xylem of opposite wood (OW). A wider expression zone of BZR1, a key transcriptional factor in BR singling pathway, was also observed in G-fiber cells on TW side than in wood fiber cells on the OW side, as indicated by immunohistochemistry assays. Transgenic poplar plants overexpressing PtiCYP85A3 produced thicker G-layer with higher cellulose proportion, and accumulated more BZR1 protein in the xylem of TW than did the wild type (WT) plants. Expression of most TW-associated CesAs, which were induced by 2, 4-epibrassinolide, an active BR, and inhibited by brassinazole, a BR biosynthesis inhibitor, were also up-regulated in the xylem of TW in transgenic plants compared to that in WT plants. Further studies with dual-luciferase assays demonstrated that the promoters of PtiCesAs were activated by PtiMYB128, a TW specific transcription factor, which was then regulated by BZR1. All these results indicate that BR plays a crucial role in the G-layer formation of TW fiber cells by regulating the expression of BZR1, PtiMYB128, and PtiCesAs in poplar.
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Affiliation(s)
- Yanli Jin
- College of Agriculture, Ludong University, Yantai, China
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- The Key Laboratory of Molecular Module-Based Breeding of High Yield and Abiotic Resistant Plants in the Universities of Shandong, Institute for Advanced Study of Coastal Ecology, Ludong University, Yantai, China
| | - Chunyan Yu
- College of Agriculture, Ludong University, Yantai, China
- The Key Laboratory of Molecular Module-Based Breeding of High Yield and Abiotic Resistant Plants in the Universities of Shandong, Institute for Advanced Study of Coastal Ecology, Ludong University, Yantai, China
| | - Chunmei Jiang
- College of Agriculture, Ludong University, Yantai, China
- Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, College of Life Sciences, Hubei University, Wuhan, China
| | - Xiaotong Guo
- College of Agriculture, Ludong University, Yantai, China
- The Key Laboratory of Molecular Module-Based Breeding of High Yield and Abiotic Resistant Plants in the Universities of Shandong, Institute for Advanced Study of Coastal Ecology, Ludong University, Yantai, China
| | - Bei Li
- College of Agriculture, Ludong University, Yantai, China
- The Key Laboratory of Molecular Module-Based Breeding of High Yield and Abiotic Resistant Plants in the Universities of Shandong, Institute for Advanced Study of Coastal Ecology, Ludong University, Yantai, China
| | - Cuiting Wang
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Fanjing Kong
- Ministry of Natural Resources Key Laboratory of Saline Lake Resources and Environments, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing, China
| | - Hongxia Zhang
- College of Agriculture, Ludong University, Yantai, China
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- The Key Laboratory of Molecular Module-Based Breeding of High Yield and Abiotic Resistant Plants in the Universities of Shandong, Institute for Advanced Study of Coastal Ecology, Ludong University, Yantai, China
| | - Haihai Wang
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
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Cuello C, Marchand P, Laurans F, Grand-Perret C, Lainé-Prade V, Pilate G, Déjardin A. ATR-FTIR Microspectroscopy Brings a Novel Insight Into the Study of Cell Wall Chemistry at the Cellular Level. Front Plant Sci 2020; 11:105. [PMID: 32153612 PMCID: PMC7047332 DOI: 10.3389/fpls.2020.00105] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 01/23/2020] [Indexed: 05/02/2023]
Abstract
Wood is a complex tissue that fulfills three major functions in trees: water conduction, mechanical support and nutrient storage. In Angiosperm trees, vessels, fibers and parenchyma rays are respectively assigned to these functions. Cell wall composition and structure strongly varies according to cell type, developmental stages and environmental conditions. This complexity can therefore hinder the study of the molecular mechanisms of wood formation, underlying the construction of its properties. However, this can be circumvented thanks to the development of cell-specific approaches and microphenotyping. Here, we present a non-destructive microphenotyping method based on attenuated total reflectance-Fourier transformed infrared (ATR-FTIR) microspectroscopy. We applied this technique to three types of poplar wood: normal wood of staked trees (NW), tension and opposite wood of artificially tilted trees (TW, OW). TW is produced by angiosperm trees in response to mechanical strains and is characterized by the presence of G fibers, exhibiting a thick gelatinous extra-layer, named G-layer, located in place of the usual S2 and/or S3 layers. By contrast, OW located on the opposite side of the trunk is totally deprived of fibers with G-layers. We developed a workflow for hyperspectral image analysis with both automatic pixel clustering according to cell wall types and identification of differentially absorbed wavenumbers (DAWNs). As pixel clustering failed to assign pixels to ray S-layers with sufficient efficiency, the IR profiling and identification of DAWNs were restricted to fiber and vessel cell walls. As reported elsewhere, this workflow identified cellulose as the main component of the G-layers, while the amount in acetylated xylans and lignins were shown to be reduced. These results validate ATR-FTIR technique for in situ characterization of G layers. In addition, this study brought new information about IR profiling of S-layers in TW, OW and NW. While OW and NW exhibited similar profiles, TW fibers S-layers combined characteristics of TW G-layers and of regular fiber S-layers. Unexpectedly, vessel S-layers of the three kinds of wood showed significant differences in IR profiling. In conclusion, ATR-FTIR microspectroscopy offers new possibilities for studying cell wall composition at the cell level.
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Affiliation(s)
| | | | - Françoise Laurans
- INRAE, ONF, BioForA, Orléans, France
- INRAE, Phenobois, Orléans, France
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Decou R, Labrousse P, Béré E, Fleurat-Lessard P, Krausz P. Structural features in tension wood and distribution of wall polymers in the G-layer of in vitro grown poplars. Protoplasma 2020; 257:13-29. [PMID: 31321553 DOI: 10.1007/s00709-019-01416-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Accepted: 07/08/2019] [Indexed: 05/19/2023]
Abstract
Under the effect of disturbances, like unbalanced stem, but also during normal development, poplar trees can develop a specific secondary xylem, called "tension wood" (TW), which is easily identifiable by the presence of a gelatinous layer in the secondary cell walls (SCW) of the xylem fibers. Since TW formation was mainly performed on 2-year-old poplar models, an in vitro poplar that produces gelatinous fibers (G-fibers) while offering the same experimental advantages as herbaceous plants has been developed. Using specific cell wall staining techniques, wood structural features and lignin/cellulose distribution were both detailed in cross-sections obtained from the curved stem part of in vitro poplars. A supposed delay in the SCW lignification process in the G-fibers, along with the presence of a G-layer, could be observed in the juvenile plants. Moreover, in this G-layer, the immunolabeling of various polymers carried out in the SCW of TW has allowed detecting crystalline cellulose, arabinogalactans proteins, and rhamnogalacturonans I; however, homogalacturonans, xylans, and xyloglucans could not be found. Interestingly, extensins were detected in this typical adaptative or stress-induced structure. These observations were corroborated by a quantitation of the immunorecognized polymer distribution using gold particle labeling. In conclusion, the in vitro poplar model seems highly convenient for TW studies focusing on the implementation of wall polymers that provide the cell wall with greater plasticity in adapting to the environment.
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Affiliation(s)
- Raphaël Decou
- University of Limoges, PEIRENE, EA 7500, F-87000, Limoges, France.
- Laboratoire de chimie des Substances naturelles, University of Limoges, UPRES EA 1069, F-87000, Limoges, France.
| | - Pascal Labrousse
- University of Limoges, PEIRENE, EA 7500, F-87000, Limoges, France
| | - Emile Béré
- Campus Sciences, Image UP, Service de Microscopie Electronique et Photonique, Pôle Biologie Santé, University of Poitiers, F-86022, Poitiers Cedex 9, France
| | - Pierrette Fleurat-Lessard
- Campus Sciences, Image UP, Service de Microscopie Electronique et Photonique, Pôle Biologie Santé, University of Poitiers, F-86022, Poitiers Cedex 9, France
- Ecologie & Biologie des Interactions, University of Poitiers, UMR CNRS 7267, F-86073, Poitiers Cedex 9, France
| | - Pierre Krausz
- Laboratoire de chimie des Substances naturelles, University of Limoges, UPRES EA 1069, F-87000, Limoges, France
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Gorshkova T, Chernova T, Mokshina N, Ageeva M, Mikshina P. Plant 'muscles': fibers with a tertiary cell wall. New Phytol 2018; 218:66-72. [PMID: 29364532 DOI: 10.1111/nph.14997] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 12/15/2017] [Indexed: 05/25/2023]
Abstract
Plants, although sessile organisms, are nonetheless able to move their body parts; for example, during root contraction of geophytes or in the gravitropic reaction by woody stems. One of the major mechanisms enabling these movements is the development of specialized structures that possess contractile properties. Quite unlike animal muscles, for which the action is driven by protein-protein interactions in the protoplasma, the action of plant 'muscles' is polysaccharide-based and located in the uniquely designed, highly cellulosic cell wall that is deposited specifically in fibers. This review describes the development of such cell walls as a widespread phenomenon in the plant kingdom, gives reasons why it should be considered as a tertiary cell wall, and discusses the mechanism of action of the 'muscles'. The origin of the contractile properties lies in the tension of the axially oriented cellulose microfibrils due to entrapment of rhamnogalacturonan-I aggregates that limits the lateral interaction of microfibrils. Long side chains of the nascent rhamnogalacturonan-I are trimmed off during cell wall maturation leading to tension development. Similarities in the tertiary cell wall design in fibers of different plant origin indicate that the basic principles of tension creation may be universal in various ecophysiological situations.
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Affiliation(s)
- Tatyana Gorshkova
- Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center, Russian Academy of Sciences, Lobachevsky Str., 2/31, Kazan, 420111, Russian Federation
| | - Tatyana Chernova
- Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center, Russian Academy of Sciences, Lobachevsky Str., 2/31, Kazan, 420111, Russian Federation
| | - Natalia Mokshina
- Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center, Russian Academy of Sciences, Lobachevsky Str., 2/31, Kazan, 420111, Russian Federation
| | - Marina Ageeva
- Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center, Russian Academy of Sciences, Lobachevsky Str., 2/31, Kazan, 420111, Russian Federation
| | - Polina Mikshina
- Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center, Russian Academy of Sciences, Lobachevsky Str., 2/31, Kazan, 420111, Russian Federation
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Clair B, Déjardin A, Pilate G, Alméras T. Is the G-Layer a Tertiary Cell Wall? Front Plant Sci 2018; 9:623. [PMID: 29868079 PMCID: PMC5952352 DOI: 10.3389/fpls.2018.00623] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 04/19/2018] [Indexed: 05/13/2023]
Affiliation(s)
- Bruno Clair
- CNRS, UMR EcoFoG, AgroParisTech, Cirad, INRA, Université des Antilles, Université de Guyane, Kourou, France
- *Correspondence: Bruno Clair
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Gorshkov O, Mokshina N, Gorshkov V, Chemikosova S, Gogolev Y, Gorshkova T. Transcriptome portrait of cellulose-enriched flax fibres at advanced stage of specialization. Plant Mol Biol 2017; 93:431-449. [PMID: 27981388 DOI: 10.1007/s11103-016-0571-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 12/02/2016] [Indexed: 05/13/2023]
Abstract
Functional specialization of cells is among the most fundamental processes of higher organism ontogenesis. The major obstacle to studying this phenomenon in plants is the difficulty of isolating certain types of cells at defined stages of in planta development for in-depth analysis. A rare opportunity is given by the developed model system of flax (Linum usitatissimum L.) phloem fibres that can be purified from the surrounding tissues at the stage of the tertiary cell wall deposition. The performed comparison of the whole transcriptome profile in isolated fibres and other portions of the flax stem, together with fibre metabolism characterization, helped to elucidate the general picture of the advanced stage of plant cell specialization and to reveal novel participants potentially involved in fibre metabolism regulation and cell wall formation. Down-regulation of all genes encoding proteins involved in xylan and lignin synthesis and up-regulation of genes for the specific set of transcription factors transcribed during tertiary cell wall formation were revealed. The increased abundance of transcripts for several glycosyltransferases indicated the enzymes that may be involved in synthesis of fibre-specific version of rhamnogalacturonan I.
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Affiliation(s)
- Oleg Gorshkov
- Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Centre, Russian Academy of Science, Lobachevsky str., 2/31, Kazan, 420111, Russia
| | - Natalia Mokshina
- Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Centre, Russian Academy of Science, Lobachevsky str., 2/31, Kazan, 420111, Russia
| | - Vladimir Gorshkov
- Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Centre, Russian Academy of Science, Lobachevsky str., 2/31, Kazan, 420111, Russia
| | - Svetlana Chemikosova
- Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Centre, Russian Academy of Science, Lobachevsky str., 2/31, Kazan, 420111, Russia
| | - Yuri Gogolev
- Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Centre, Russian Academy of Science, Lobachevsky str., 2/31, Kazan, 420111, Russia
| | - Tatyana Gorshkova
- Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Centre, Russian Academy of Science, Lobachevsky str., 2/31, Kazan, 420111, Russia.
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Ibragimova NN, Ageeva MV, Gorshkova TA. Development of gravitropic response: unusual behavior of flax phloem G-fibers. Protoplasma 2017; 254:749-762. [PMID: 27263083 DOI: 10.1007/s00709-016-0985-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 05/13/2016] [Indexed: 05/25/2023]
Abstract
The major mechanism of gravitropism that is discussed for herbal plants is based on the nonuniform elongation of cells located on the opposite stem sides, occurring in the growing zone of an organ. However, gravitropic response of flax (Linum usitatissimum L.) is well-pronounced in the lower half of developing stem, which has ceased elongation long in advance of plant inclination. We have analyzed the stem curvature region by various approaches of microscopy and found the undescribed earlier significant modifications in primary phloem fibers that have constitutively developed G-layer. In fibers on the pulling stem side, cell portions were widened with formation of "bottlenecks" between them, leading to the "sausage-like" shape of a cell. Lumen diameter in fiber widening increased, while cell wall thickness decreased. Callose was deposited in proximity to bottlenecks and sometimes totally occluded their lumen. Structure of fiber cell wall changed considerably, with formation of breaks between G- and S-layers. Thick fibrillar structures that were revealed in fiber cell wall by light microscopy got oblique orientation instead of parallel to the fiber axis one in control plants. The described changes occurred at various combinations of gravitational and mechanical stimuli. Thus, phloem fibers with constitutively formed gelatinous cell wall, located in nonelongating parts of herbal plant, are involved in gravitropism and may become an important element in general understanding of the gravity effects on plants. We suggest flax phloem fibers as the model system to study the mechanism of plant position correction, including signal perception and transduction.
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Affiliation(s)
- Nadezda N Ibragimova
- Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center, Russian Academy of Sciences, Lobachevsky Str. 2/31, Kazan, 420111, Russia.
| | - Marina V Ageeva
- Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center, Russian Academy of Sciences, Lobachevsky Str. 2/31, Kazan, 420111, Russia
| | - Tatyana A Gorshkova
- Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center, Russian Academy of Sciences, Lobachevsky Str. 2/31, Kazan, 420111, Russia
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Abstract
Trees control their posture by generating asymmetric mechanical stress around the periphery of the trunk or branches. This stress is produced in wood during the maturation of the cell wall. When the need for reaction is high, it is accompanied by strong changes in cell organization and composition called reaction wood, namely compression wood in gymnosperms and tension wood in angiosperms. The process by which stress is generated in the cell wall during its formation is not yet known, and various hypothetical mechanisms have been proposed in the literature. Here we aim at discriminating between these models. First, we summarize current knowledge about reaction wood structure, state and behaviour relevant to the understanding of maturation stress generation. Then, the mechanisms proposed in the literature are listed and discussed in order to identify which can be rejected based on their inconsistency with current knowledge at the frontier between plant science and mechanical engineering.
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Affiliation(s)
- Tancrède Alméras
- Laboratoire de Mécanique et Génie Civil (LMGC), CNRS, Université de Montpellier, cc 048, Place E. Bataillon, 34095 Montpellier, France
| | - Bruno Clair
- CNRS, UMR Ecologie des Forêts de Guyane (EcoFoG), AgroParisTech, Cirad, INRA, Université des Antilles, Université de Guyane, 97310 Kourou, France
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