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Priatama RA, Heo J, Kim SH, Rajendran S, Yoon S, Jeong DH, Choo YK, Bae JH, Kim CM, Lee YH, Demura T, Lee YK, Choi EY, Han CD, Park SJ. Narrow lpa1 Metaxylems Enhance Drought Tolerance and Optimize Water Use for Grain Filling in Dwarf Rice. Front Plant Sci 2022; 13:894545. [PMID: 35620680 PMCID: PMC9127761 DOI: 10.3389/fpls.2022.894545] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 04/19/2022] [Indexed: 05/31/2023]
Abstract
Rice cultivation needs extensive amounts of water. Moreover, increased frequency of droughts and water scarcity has become a global concern for rice cultivation. Hence, optimization of water use is crucial for sustainable agriculture. Here, we characterized Loose Plant Architecture 1 (LPA1) in vasculature development, water transport, drought resistance, and grain yield. We performed genetic combination of lpa1 with semi-dwarf mutant to offer the optimum rice architecture for more efficient water use. LPA1 expressed in pre-vascular cells of leaf primordia regulates genes associated with carbohydrate metabolism and cell enlargement. Thus, it plays a role in metaxylem enlargement of the aerial organs. Narrow metaxylem of lpa1 exhibit leaves curling on sunny day and convey drought tolerance but reduce grain yield in mature plants. However, the genetic combination of lpa1 with semi-dwarf mutant (dep1-ko or d2) offer optimal water supply and drought resistance without impacting grain-filling rates. Our results show that water use, and transports can be genetically controlled by optimizing metaxylem vessel size and plant height, which may be utilized for enhancing drought tolerance and offers the potential solution to face the more frequent harsh climate condition in the future.
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Affiliation(s)
- Ryza A. Priatama
- Division of Applied Life Science (BK21 Program), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Gyeongsang National University, Jinju, South Korea
- Institute of Plasma Technology, Korea Institute of Fusion Energy, Gunsan, South Korea
| | - Jung Heo
- Division of Biological Sciences and Research Institute for Basic Science, Wonkwang University, Iksan, South Korea
| | - Sung Hoon Kim
- Division of Applied Life Science (BK21 Program), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Gyeongsang National University, Jinju, South Korea
- Environmental Exposure & Toxicology Research Center, Korea Institute of Toxicology, Jinju, South Korea
| | - Sujeevan Rajendran
- Division of Biological Sciences and Research Institute for Basic Science, Wonkwang University, Iksan, South Korea
| | - Seoa Yoon
- Department of Horticulture Industry, Wonkwang University, Iksan, South Korea
| | - Dong-Hoon Jeong
- Department of Life Science and Multidisciplinary Genome Institute, Hallym University, Chuncheon, South Korea
| | - Young-Kug Choo
- Division of Biological Sciences and Research Institute for Basic Science, Wonkwang University, Iksan, South Korea
| | - Jong Hyang Bae
- Department of Horticulture Industry, Wonkwang University, Iksan, South Korea
| | - Chul Min Kim
- Department of Horticulture Industry, Wonkwang University, Iksan, South Korea
| | - Yeon Hee Lee
- National Institute of Agricultural Biotechnology, Suwon, South Korea
| | - Taku Demura
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan
| | - Young Koung Lee
- Institute of Plasma Technology, Korea Institute of Fusion Energy, Gunsan, South Korea
| | - Eun-Young Choi
- Department of Agricultural Science, Korea National Open University, Seoul, South Korea
| | - Chang-deok Han
- Division of Applied Life Science (BK21 Program), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Gyeongsang National University, Jinju, South Korea
| | - Soon Ju Park
- Division of Biological Sciences and Research Institute for Basic Science, Wonkwang University, Iksan, South Korea
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Fonta JE, Vejchasarn P, Henry A, Lynch JP, Brown KM. Many paths to one goal: Identifying integrated rice root phenotypes for diverse drought environments. Front Plant Sci 2022; 13:959629. [PMID: 36072326 PMCID: PMC9441928 DOI: 10.3389/fpls.2022.959629] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 07/28/2022] [Indexed: 05/02/2023]
Abstract
Drought is a major source of yield loss in the production of rice (Oryza sativa L.), and cultivars that maintain yield under drought across environments and drought stress scenarios are urgently needed. Root phenotypes directly affect water interception and uptake, so plants with root systems optimized for water uptake under drought would likely exhibit reduced yield loss. Deeper nodal roots that have a low metabolic cost per length (i.e., cheaper roots) via smaller root diameter and/or more aerenchyma and that transport water efficiently through smaller diameter metaxylem vessels may be beneficial during drought. Subsets of the Rice Diversity Panel 1 and Azucena × IR64 recombinant inbred lines were grown in two greenhouse and two rainout shelter experiments under drought stress to assess their shoot, root anatomical, and root architectural phenotypes. Root traits and root trait plasticity in response to drought varied with genotype and environment. The best-performing groups in the rainout shelter experiments had less plasticity of living tissue area in nodal roots than the worst performing groups. Root traits under drought were partitioned into similar groups or clusters via the partitioning-around-medoids algorithm, and this revealed two favorable integrated root phenotypes common within and across environments. One favorable integrated phenotype exhibited many, deep nodal roots with larger root cross-sectional area and more aerenchyma, while the other favorable phenotype exhibited many, deep nodal roots with small root cross-sectional area and small metaxylem vessels. Deeper roots with high theoretical axial hydraulic conductance combined with reduced root metabolic cost contributed to greater shoot biomass under drought. These results reflect how some root anatomical and architectural phenes work in concert as integrated phenotypes to influence the performance of plant under drought stress. Multiple integrated root phenotypes are therefore recommended to be selected in breeding programs for improving rice yield across diverse environments and drought scenarios.
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Affiliation(s)
- Jenna E. Fonta
- Intercollege Graduate Degree Program in Plant Biology, Huck Institutes of the Life Sciences, Penn State University, University Park, PA, United States
- Department of Plant Science, The Pennsylvania State University, University Park, PA, United States
| | - Phanchita Vejchasarn
- Rice Department, Ministry of Agriculture, Ubon Ratchathani Rice Research Center, Ubon Ratchathani, Thailand
| | - Amelia Henry
- Rice Breeding Innovations Platform, International Rice Research Institute (IRRI), Los Baños, Philippines
| | - Jonathan P. Lynch
- Department of Plant Science, The Pennsylvania State University, University Park, PA, United States
| | - Kathleen M. Brown
- Department of Plant Science, The Pennsylvania State University, University Park, PA, United States
- *Correspondence: Kathleen M. Brown,
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Pereira YC, da Silva FR, da Silva BRS, Cruz FJR, Marques DJ, Lobato AKDS. 24-epibrassinolide induces protection against waterlogging and alleviates impacts on the root structures, photosynthetic machinery and biomass in soybean. Plant Signal Behav 2020; 15:1805885. [PMID: 32787497 PMCID: PMC7588182 DOI: 10.1080/15592324.2020.1805885] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [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: 06/27/2020] [Revised: 07/30/2020] [Accepted: 08/02/2020] [Indexed: 05/20/2023]
Abstract
Plants exhibit several restrictions under waterlogging conditions, including stomatal limitations, negative impacts on gas exchange, lower nutrient uptake and reduced growth. 24-epibrassinolide (EBR) is a polyhydroxylated steroid, with the advantages to be a natural and biodegradable molecule, presenting beneficial roles in metabolic and physiological processes. The aim of this research is to investigate whether EBR can protect soybean plants against damage caused by waterlogging and evaluate the responses associated with the root and leaf anatomy, photosynthetic machinery and biomass. This study used a completely randomized factorial design with two water conditions (control and waterlogging) and three concentrations of 24-epibrassinolide (0, 5 and 10 nM EBR). This steroid stimulated the activities of enzymes linked to the antioxidant system and resulted in minor damage to the chloroplast membranes. EBR maximized the efficiency of photosystem II and improved the gas exchange, which was explained by the higher density and index of the stomata in addition to the increased chlorophyll content and electron transport rate. In root structures, EBR mitigated the impact of waterlogging on vascular cylinder and metaxilem, suggesting maintenance and functions of these structures in plants stressed.
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Affiliation(s)
- Ynglety Cascaes Pereira
- Núcleo de Pesquisa Vegetal Básica e Aplicada, Universidade Federal Rural da Amazônia, Paragominas, Brazil
| | | | | | | | - Douglas José Marques
- Instituto de Ciências Agrárias, Universidade Federal de Uberlândia, Monte Carmelo, Brazil
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Saito S, Niki T, Gladish DK. Evaluation of Metaxylem Vessel Histogenesis and the Occurrence of Vessel Collapse during Early Development in Primary Roots of Zea mays ssp. mexicana: A Result of Premature Programmed Cell Death? Plants (Basel) 2020; 9:E374. [PMID: 32197442 DOI: 10.3390/plants9030374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 03/08/2020] [Accepted: 03/13/2020] [Indexed: 12/04/2022]
Abstract
Root apical meristem histological organization in Zea mays has been carefully studied previously. Classical histology describes its system as having a “closed organization” and a development of xylem that conforms to predictable rules. Among the first cell types to begin differentiation are late-maturing metaxylem (LMX) vessels. As part of a larger study comparing domestic maize root development to a wild subspecies of Z. mays (teosinte), we encountered a metaxylem development abnormality in a small percentage of our specimens that begged further study, as it interrupted normal maturation of LMX. Primary root tips of young seedlings of Zea mays ssp. mexicana were fixed, embedded in appropriate resins, and sectioned for light and transmission electron microscopy. Longitudinal and serial transverse sections were analyzed using computer imaging to determine the position and timing of key xylem developmental events. We observed a severe abnormality of LMX development among 3.5% of the 227 mexicana seedlings we screened. All LMX vessel elements in these abnormal roots collapsed and probably became non-functional shortly after differentiation began. Cytoplasm and nucleoplasm in the abnormal LMX elements became condensed and subdivided into irregularly-shaped “macrovesicles” as their cell walls collapsed inward. We propose that these seedlings possibly suffered from a mutation that affected the timing of the programmed cell death (PCD) that is required to produce functional xylem vessels, such that autolysis of the cytoplasm was prematurely executed, i.e., prior to the development and lignification of secondary walls.
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Saito S, Niki T, Gladish DK. Comparison of Promeristem Structure and Ontogeny of Procambium in Primary Roots of Zea mays ssp. Mexicana and Z. mays 'Honey Bantam' with Emphasis on Metaxylem Vessel Histogenesis. Plants (Basel) 2019; 8:E162. [PMID: 31181793 PMCID: PMC6631287 DOI: 10.3390/plants8060162] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2019] [Revised: 05/23/2019] [Accepted: 06/04/2019] [Indexed: 12/01/2022]
Abstract
Classical histology describes the histological organization in Zea mays as having a "closed organization" that differs from Arabidopsis with the development of xylem conforming to predictable rules. We speculated that root apical meristem organization in a wild subspecies of Z. mays (a teosinte) would differ from a domestic sweetcorn cultivar ('Honey Bantam'). Careful comparison could contribute to understanding how evolutionary processes and the domestication of maize have affected root development. Root tips of seedlings were prepared and sectioned for light microscopy. Most sections were treated with RNase before staining to increase contrast between the walls and cytoplasm. Longitudinal and serial transverse sections were analyzed using computer imaging to determine the position and timing of key xylem developmental events. Metaxylem development in mexicana teosinte differed from sweetcorn only in that the numbers of late-maturing metaxylem vessels in the latter are typically two-fold greater and the number of cells in the transverse section of procambium were greater in the latter, but parenchymatous cell sizes were not statistically different. Promeristems of both were nearly identical in size and organization, but did not operate quite as previously described. Mitotic activity was rare in the quiescent centers, but occasionally a synchronized pulse of mitoses was observed there. Our reinterpretation of histogen theory and procambium development should be useful for future detailed studies of regulation of development, and perhaps its evolution, in this species.
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Affiliation(s)
- Susumu Saito
- Department of Biotechnology, Takushoku University, Tatemachi 815-1, Hachioji, Tokyo 193-0985, Japan.
| | - Teruo Niki
- Department of Biotechnology, Takushoku University, Tatemachi 815-1, Hachioji, Tokyo 193-0985, Japan.
| | - Daniel K Gladish
- Biological Sciences Department, Miami University, 1601 University Blvd, Hamilton, OH 45011, USA.
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Fattorini L, Della Rovere F, Andreini E, Ronzan M, Falasca G, Altamura MM. Indole-3-Butyric Acid Induces Ectopic Formation of Metaxylem in the Hypocotyl of Arabidopsis thaliana without Conversion into Indole-3-Acetic Acid and with a Positive Interaction with Ethylene. Int J Mol Sci 2017; 18:E2474. [PMID: 29160805 DOI: 10.3390/ijms18112474] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 11/13/2017] [Accepted: 11/16/2017] [Indexed: 12/15/2022] Open
Abstract
The role of the auxins indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) and of the auxin-interacting phytohormone ethylene, on the ectopic formation of primary xylem (xylogenesis in planta) is still little known. In particular, auxin/ethylene-target tissue(s), modality of the xylary process (trans-differentiation vs. de novo formation), and the kind of ectopic elements formed (metaxylem vs. protoxylem) are currently unknown. It is also unclear whether IBA may act on the process independently of conversion into IAA. To investigate these topics, histological analyses were carried out in the hypocotyls of Arabidopsis wild type seedlings and ech2ibr10 and ein3eil1 mutants, which are blocked in IBA-to-IAA conversion and ethylene signalling, respectively. The seedlings were grown under darkness with either IAA or IBA, combined or not with the ethylene precursor 1-aminocyclopropane-1-carboxylic acid. Adventitious root formation was also investigated because this process may compete with xylogenesis. Our results show that ectopic formation of protoxylem and metaxylem occurred as an indirect process starting from the pericycle periclinal derivatives of the hypocotyl basal part. IAA favoured protoxylem formation, whereas IBA induced ectopic metaxylem with ethylene cooperation through the EIN3EIL1 network. Ectopic metaxylem differentiation occurred independently of IBA-to-IAA conversion as mediated by ECH2 and IBR10, and in the place of IBA-induced adventitious root formation.
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Alabdallah O, Ahou A, Mancuso N, Pompili V, Macone A, Pashkoulov D, Stano P, Cona A, Angelini R, Tavladoraki P. The Arabidopsis polyamine oxidase/dehydrogenase 5 interferes with cytokinin and auxin signaling pathways to control xylem differentiation. J Exp Bot 2017; 68:997-1012. [PMID: 28199662 DOI: 10.1093/jxb/erw510] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In plants, the polyamines putrescine, spermidine, spermine (Spm), and thermospermine (Therm-Spm) participate in several physiological processes. In particular, Therm-Spm is involved in the control of xylem differentiation, having an auxin antagonizing effect. Polyamine oxidases (PAOs) are FAD-dependent enzymes involved in polyamine catabolism. In Arabidopsis, five PAOs are present, among which AtPAO5 catalyzes the back-conversion of Spm, Therm-Spm, and N1-acetyl-Spm to spermidine. In the present study, it is shown that two loss-of-function atpao5 mutants and a 35S::AtPAO5 Arabidopsis transgenic line present phenotypical differences from the wild-type plants with regard to stem and root elongation, differences that are accompanied by changes in polyamine levels and the number of xylem vessels. It is additionally shown that cytokinin treatment, which up-regulates AtPAO5 expression in roots, differentially affects protoxylem differentiation in 35S::AtPAO5, atpao5, and wild-type roots. Together with these findings, Therm-Spm biosynthetic genes, as well as auxin-, xylem-, and cytokinin-related genes (such as ACL5, SAMDC4, PIN1, PIN6, VND6, VND7, ATHB8, PHB, CNA, PXY, XTH3, XCP1, and AHP6) are shown to be differentially expressed in the various genotypes. These data suggest that AtPAO5, being involved in the control of Therm-Spm homeostasis, participates in the tightly controlled interplay between auxin and cytokinins that is necessary for proper xylem differentiation.
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Affiliation(s)
| | - Abdellah Ahou
- Department of Sciences, University 'ROMA TRE', Rome, Italy
| | | | | | - Alberto Macone
- Department of Biochemical Sciences 'A. Rossi Fanelli', University of Rome 'La Sapienza', Rome, Italy
| | - Dimitre Pashkoulov
- Società Agricola Floramiata Servizi srl, 53025 Piancastagnaio, Siena, Italy
| | - Pasquale Stano
- Department of Sciences, University 'ROMA TRE', Rome, Italy
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Passot S, Gnacko F, Moukouanga D, Lucas M, Guyomarc’h S, Ortega BM, Atkinson JA, Belko MN, Bennett MJ, Gantet P, Wells DM, Guédon Y, Vigouroux Y, Verdeil JL, Muller B, Laplaze L. Characterization of Pearl Millet Root Architecture and Anatomy Reveals Three Types of Lateral Roots. Front Plant Sci 2016; 7:829. [PMID: 27379124 PMCID: PMC4904005 DOI: 10.3389/fpls.2016.00829] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 05/26/2016] [Indexed: 05/04/2023]
Abstract
Pearl millet plays an important role for food security in arid regions of Africa and India. Nevertheless, it is considered an orphan crop as it lags far behind other cereals in terms of genetic improvement efforts. Breeding pearl millet varieties with improved root traits promises to deliver benefits in water and nutrient acquisition. Here, we characterize early pearl millet root system development using several different root phenotyping approaches that include rhizotrons and microCT. We report that early stage pearl millet root system development is characterized by a fast growing primary root that quickly colonizes deeper soil horizons. We also describe root anatomical studies that revealed three distinct types of lateral roots that form on both primary roots and crown roots. Finally, we detected significant variation for two root architectural traits, primary root lenght and lateral root density, in pearl millet inbred lines. This study provides the basis for subsequent genetic experiments to identify loci associated with interesting early root development traits in this important cereal.
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Affiliation(s)
- Sixtine Passot
- UMR DIADE, Institut de Recherche pour le Développement, MontpellierFrance
- UMR AGAP, Centre International de Recherche Agronomique pour le Développement–Virtual Plants, Institut National de Recherche en Informatique et en Automatique, MontpellierFrance
| | - Fatoumata Gnacko
- UMR DIADE, Institut de Recherche pour le Développement, MontpellierFrance
| | - Daniel Moukouanga
- UMR DIADE, Institut de Recherche pour le Développement, MontpellierFrance
- Laboratoire Mixte International Adaptation des Plantes et Microorganismes Associés aux Stress Environnementaux, DakarSénégal
| | - Mikaël Lucas
- UMR DIADE, Institut de Recherche pour le Développement, MontpellierFrance
- Laboratoire Mixte International Adaptation des Plantes et Microorganismes Associés aux Stress Environnementaux, DakarSénégal
- Laboratoire Commun de Microbiologie IRD/ISRA/UCAD, DakarSénégal
| | | | - Beatriz Moreno Ortega
- Laboratoire d’Ecophysiologie des Plantes sous Stress Environnementaux (UMR LEPSE, INRA-Supagro), MontpellierFrance
| | - Jonathan A. Atkinson
- Centre for Plant Integrative Biology, School of Biosciences, University of Nottingham, Sutton BoningtonUK
| | - Marème N. Belko
- Laboratoire Mixte International Adaptation des Plantes et Microorganismes Associés aux Stress Environnementaux, DakarSénégal
- Centre d’Etude Régional pour l’Amélioration de l’Adaptation à la Sécheresse, Institut Sénégalais des Recherches Agricoles, ThièsSénégal
| | - Malcolm J. Bennett
- Centre for Plant Integrative Biology, School of Biosciences, University of Nottingham, Sutton BoningtonUK
| | - Pascal Gantet
- UMR DIADE, Université de Montpellier, MontpellierFrance
| | - Darren M. Wells
- Centre for Plant Integrative Biology, School of Biosciences, University of Nottingham, Sutton BoningtonUK
| | - Yann Guédon
- UMR AGAP, Centre International de Recherche Agronomique pour le Développement–Virtual Plants, Institut National de Recherche en Informatique et en Automatique, MontpellierFrance
| | - Yves Vigouroux
- UMR DIADE, Institut de Recherche pour le Développement, MontpellierFrance
- Laboratoire Mixte International Adaptation des Plantes et Microorganismes Associés aux Stress Environnementaux, DakarSénégal
| | - Jean-Luc Verdeil
- Plateforme PHIV, UMR AGAP, Centre International de Recherche Agricole pour le Développement, MontpellierFrance
| | - Bertrand Muller
- Laboratoire d’Ecophysiologie des Plantes sous Stress Environnementaux (UMR LEPSE, INRA-Supagro), MontpellierFrance
| | - Laurent Laplaze
- UMR DIADE, Institut de Recherche pour le Développement, MontpellierFrance
- Laboratoire Mixte International Adaptation des Plantes et Microorganismes Associés aux Stress Environnementaux, DakarSénégal
- Laboratoire Commun de Microbiologie IRD/ISRA/UCAD, DakarSénégal
- *Correspondence: Laurent Laplaze,
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Euring D, Bai H, Janz D, Polle A. Nitrogen-driven stem elongation in poplar is linked with wood modification and gene clusters for stress, photosynthesis and cell wall formation. BMC Plant Biol 2014; 14:391. [PMID: 25547614 PMCID: PMC4302602 DOI: 10.1186/s12870-014-0391-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [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: 09/22/2014] [Accepted: 12/18/2014] [Indexed: 05/05/2023]
Abstract
BACKGROUND Nitrogen is an important nutrient, often limiting plant productivity and yield. In poplars, woody crops used as feedstock for renewable resources and bioenergy, nitrogen fertilization accelerates growth of the young, expanding stem internodes. The underlying molecular mechanisms of nitrogen use for extension growth in poplars are not well understood. The aim of this study was to dissect the nitrogen-responsive transcriptional network in the elongation zone of Populus trichocarpa in relation to extension growth and cell wall properties. RESULTS Transcriptome analyses in the first two internodes of P. trichocarpa stems grown without or with nitrogen fertilization (5 mM NH4NO3) revealed 1037 more than 2-fold differentially expressed genes (DEGs). Co-expression analysis extracted a network containing about one-third of the DEGs with three main complexes of strongly clustered genes. These complexes represented three main processes that were responsive to N-driven growth: Complex 1 integrated growth processes and stress suggesting that genes with established functions in abiotic and biotic stress are also recruited to coordinate growth. Complex 2 was enriched in genes with decreased transcript abundance and functionally annotated as photosynthetic hub. Complex 3 was a hub for secondary cell wall formation connecting well-known transcription factors that control secondary cell walls with genes for the formation of cellulose, hemicelluloses, and lignin. Anatomical and biochemical analysis supported that N-driven growth resulted in early secondary cell wall formation in the elongation zone with thicker cell walls and increased lignin. These alterations contrasted the N influence on the secondary xylem, where thinner cell walls with lower lignin contents than in unfertilized trees were formed. CONCLUSION This study uncovered that nitrogen-responsive elongation growth of poplar internodes is linked with abiotic stress, suppression of photosynthetic genes and stimulation of genes for cell wall formation. Anatomical and biochemical analysis supported increased accumulation of cell walls and secondary metabolites in the elongation zone. The finding of a nitrogen-responsive cell wall hub may have wider implications for the improvement of tree nitrogen use efficiency and opens new perspectives on the enhancement of wood composition as a feedstock for biofuels.
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Affiliation(s)
- Dejuan Euring
- Forest Botany and Tree Physiology, Georg-August Universität Göttingen, Büsgenweg 2, 37077 Göttingen, Germany
| | - Hua Bai
- Forest Botany and Tree Physiology, Georg-August Universität Göttingen, Büsgenweg 2, 37077 Göttingen, Germany
| | - Dennis Janz
- Forest Botany and Tree Physiology, Georg-August Universität Göttingen, Büsgenweg 2, 37077 Göttingen, Germany
| | - Andrea Polle
- Forest Botany and Tree Physiology, Georg-August Universität Göttingen, Büsgenweg 2, 37077 Göttingen, Germany
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NAKABAYASHI IZUMI, KARAHARA ICHIROU, TAMAOKI DAISUKE, MASUDA KYOJIRO, WAKASUGI TATSUYA, YAMADA KYOJI, SOGA KOUICHI, HOSON TAKAYUKI, KAMISAKA SEIICHIRO. Hypergravity stimulus enhances primary xylem development and decreases mechanical properties of secondary cell walls in inflorescence stems of Arabidopsis thaliana. Ann Bot 2006; 97:1083-90. [PMID: 16537641 PMCID: PMC2803380 DOI: 10.1093/aob/mcl055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 09/26/2005] [Revised: 12/09/2005] [Accepted: 02/08/2006] [Indexed: 05/07/2023]
Abstract
BACKGROUND AND AIMS The xylem plays an important role in strengthening plant bodies. Past studies on xylem formation in tension woods in poplar and also in clinorotated Prunus tree stems lead to the suggestion that changes in the gravitational conditions affect morphology and mechanical properties of xylem vessels. The aim of this study was to examine effects of hypergravity stimulus on morphology and development of primary xylem vessels and on mechanical properties of isolated secondary wall preparations in inflorescence stems of arabidopsis. METHODS Morphology of primary xylem was examined under a light microscope on cross-sections of inflorescence stems of arabidopsis plants, which had been grown for 3-5 d after exposure to hypergravity at 300 g for 24 h. Extensibility of secondary cell wall preparation, isolated from inflorescence stems by enzyme digestion of primary cell wall components (mainly composed of metaxylem elements), was examined. Plants were treated with gadolinium chloride, a blocker of mechanoreceptors, to test the involvement of mechanoreceptors in the responses to hypergravity. KEY RESULTS Number of metaxylem elements per xylem, apparent thickness of the secondary thickenings, and cross-section area of metaxylem elements in inflorescence stems increased in response to hypergravity. Gadolinium chloride suppressed the effect of hypergravity on the increase both in the thickness of secondary thickenings and in the cross-section area of metaxylem elements, while it did not suppress the effect of hypergravity on the increase in the number of metaxylem elements. Extensibility of secondary cell wall preparation decreased in response to hypergravity. Gadolinium chloride suppressed the effect of hypergravity on cell wall extensibility. CONCLUSIONS Hypergravity stimulus promotes metaxylem development and decreases extensibility of secondary cell walls, and mechanoreceptors were suggested to be involved in these processes.
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Affiliation(s)
- IZUMI NAKABAYASHI
- Department of Biology, Faculty of Science, Toyama University, Toyama, 930-8555, Japan and Graduate School of Science, Osaka City University, Sumiyoshi-ku, 558-8585, Osaka, Japan
| | - ICHIROU KARAHARA
- Department of Biology, Faculty of Science, Toyama University, Toyama, 930-8555, Japan and Graduate School of Science, Osaka City University, Sumiyoshi-ku, 558-8585, Osaka, Japan
| | - DAISUKE TAMAOKI
- Department of Biology, Faculty of Science, Toyama University, Toyama, 930-8555, Japan and Graduate School of Science, Osaka City University, Sumiyoshi-ku, 558-8585, Osaka, Japan
| | - KYOJIRO MASUDA
- Department of Biology, Faculty of Science, Toyama University, Toyama, 930-8555, Japan and Graduate School of Science, Osaka City University, Sumiyoshi-ku, 558-8585, Osaka, Japan
| | - TATSUYA WAKASUGI
- Department of Biology, Faculty of Science, Toyama University, Toyama, 930-8555, Japan and Graduate School of Science, Osaka City University, Sumiyoshi-ku, 558-8585, Osaka, Japan
| | - KYOJI YAMADA
- Department of Biology, Faculty of Science, Toyama University, Toyama, 930-8555, Japan and Graduate School of Science, Osaka City University, Sumiyoshi-ku, 558-8585, Osaka, Japan
| | - KOUICHI SOGA
- Department of Biology, Faculty of Science, Toyama University, Toyama, 930-8555, Japan and Graduate School of Science, Osaka City University, Sumiyoshi-ku, 558-8585, Osaka, Japan
| | - TAKAYUKI HOSON
- Department of Biology, Faculty of Science, Toyama University, Toyama, 930-8555, Japan and Graduate School of Science, Osaka City University, Sumiyoshi-ku, 558-8585, Osaka, Japan
| | - SEIICHIRO KAMISAKA
- Department of Biology, Faculty of Science, Toyama University, Toyama, 930-8555, Japan and Graduate School of Science, Osaka City University, Sumiyoshi-ku, 558-8585, Osaka, Japan
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Abstract
BACKGROUND AND AIMS Petioles of huge solitary leaves of mature plants of Amorphophallus resemble tree trunks supporting an umbrella-like crown. Since they may be 4 m tall, adaptations to water transport in the petioles are as important as adaptations to mechanical support of lamina. The petiole is a cylindrical shell composed of compact unlignified tissue with a honeycomb aerenchymatous core. In both parts numerous vascular bundles occur, which are unique because of the scarcity of lignified elements. In the xylemic part of each bundle there is a characteristic canal with unlignified walls. The xylem pecularities are described and interpreted. MATERIAL Vascular bundles in mature petioles of Amorphophallus titanum and A. gigas plants were studied using light and scanning electron microscopy. KEY RESULTS The xylemic canal represents a file of huge metaxylem tracheids (diameter 55-200 microm, length >30 mm) with unlignified lateral walls surrounded by turgid parenchyma cells. Only their end walls, orientated steeply, have lignified secondary thickenings. The file is accompanied by a strand of narrow tracheids with lignified bar-type secondary walls, which come into direct contact with the wide tracheid in many places along its length. CONCLUSIONS The metaxylem tracheids in A. petioles are probably the longest and widest tracheids known. Only their end walls have lignified secondary thickenings. Tracheids are long due to enormous intercalary elongation and wide due to a transverse growth mechanism similar to that underlying formation of aerenchyma cavities. The lack of lignin in lateral walls shifts the function of 'pipe walls' to the turgid parenchyma paving the tracheid. The analogy to carinal canals of Equisetum, as well as other protoxylem lacunas is discussed. The stiff partitions between the long and wide tracheids are interpreted as structures similar to the end walls in vessels.
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Affiliation(s)
- Zygmunt Hejnowicz
- Department of Biophysics and Cell Biology, Silesian University, Jagiellonska 28, Katowice 40-032, Poland.
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