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Bouidghaghen J, Moreau L, Beauchêne K, Chapuis R, Mangel N, Cabrera-Bosquet L, Welcker C, Bogard M, Tardieu F. Robotized indoor phenotyping allows genomic prediction of adaptive traits in the field. Nat Commun 2023; 14:6603. [PMID: 37857601 PMCID: PMC10587076 DOI: 10.1038/s41467-023-42298-z] [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] [Received: 04/30/2023] [Accepted: 10/06/2023] [Indexed: 10/21/2023] Open
Abstract
Breeding for resilience to climate change requires considering adaptive traits such as plant architecture, stomatal conductance and growth, beyond the current selection for yield. Robotized indoor phenotyping allows measuring such traits at high throughput for speed breeding, but is often considered as non-relevant for field conditions. Here, we show that maize adaptive traits can be inferred in different fields, based on genotypic values obtained indoor and on environmental conditions in each considered field. The modelling of environmental effects allows translation from indoor to fields, but also from one field to another field. Furthermore, genotypic values of considered traits match between indoor and field conditions. Genomic prediction results in adequate ranking of genotypes for the tested traits, although with lesser precision for elite varieties presenting reduced phenotypic variability. Hence, it distinguishes genotypes with high or low values for adaptive traits, conferring either spender or conservative strategies for water use under future climates.
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Affiliation(s)
- Jugurta Bouidghaghen
- LEPSE, Univ Montpellier, INRAE, Montpellier, France
- ARVALIS, Chemin de la côte vieille, Baziège, France
| | - Laurence Moreau
- GQE-Le Moulon, INRAE, Université Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Katia Beauchêne
- ARVALIS, 45 Voie Romaine, Ouzouer-Le-Marché, Beauce La Romaine, France
| | | | - Nathalie Mangel
- ARVALIS, Station de recherche et d'expérimentation, Boigneville, France
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Coussement JR, Villers SLY, Nelissen H, Inzé D, Steppe K. Turgor-time controls grass leaf elongation rate and duration under drought stress. PLANT, CELL & ENVIRONMENT 2021; 44:1361-1378. [PMID: 33373049 DOI: 10.1111/pce.13989] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 12/17/2020] [Accepted: 12/21/2020] [Indexed: 06/12/2023]
Abstract
The process of leaf elongation in grasses is characterized by the creation and transformation of distinct cell zones. The prevailing turgor pressure within these cells is one of the key drivers for the rate at which these cells divide, expand and differentiate, processes that are heavily impacted by drought stress. In this article, a turgor-driven growth model for grass leaf elongation is presented, which combines mechanistic growth from the basis of turgor pressure with the ontogeny of the leaf. Drought-induced reductions in leaf turgor pressure result in a simultaneous inhibition of both cell expansion and differentiation, lowering elongation rate but increasing elongation duration due to the slower transitioning of cells from the dividing and elongating zone to mature cells. Leaf elongation is, therefore, governed by the magnitude of, and time spent under, growth-enabling turgor pressure, a metric which we introduce as turgor-time. Turgor-time is able to normalize growth patterns in terms of varying water availability, similar to how thermal time is used to do so under varying temperatures. Moreover, additional inclusion of temperature dependencies within our model pioneers a novel concept enabling the general expression of growth regardless of water availability or temperature.
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Affiliation(s)
- Jonas R Coussement
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Selwyn L Y Villers
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Hilde Nelissen
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Dirk Inzé
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Kathy Steppe
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
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3
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Barillot R, De Swaef T, Combes D, Durand JL, Escobar-Gutiérrez AJ, Martre P, Perrot C, Roy E, Frak E. Leaf elongation response to blue light is mediated by stomatal-induced variations in transpiration in Festuca arundinacea. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:2642-2656. [PMID: 33326568 DOI: 10.1093/jxb/eraa585] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 12/14/2020] [Indexed: 06/12/2023]
Abstract
Reduced blue light irradiance is known to enhance leaf elongation rate (LER) in grasses, but the mechanisms involved have not yet been elucidated. We investigated whether leaf elongation response to reduced blue light could be mediated by stomata-induced variations of plant transpiration. Two experiments were carried out on tall fescue in order to monitor LER and transpiration under reduced blue light irradiance. Additionally, LER dynamics were compared with those observed in the response to vapour pressure deficit (VPD)-induced variations of transpiration. Finally, we developed a model of water flow within a tiller to simulate the observed short-term response of LER to various transpiration regimes. LER dramatically increased in response to blue light reduction and then reached new steady states, which remained higher than the control. Reduced blue light triggered a simultaneous stomatal closure which induced an immediate decrease of leaf transpiration. The hydraulic model of leaf elongation accurately predicted the LER response to blue light and VPD, resulting from an increase in the growth-induced water potential gradient in the leaf growth zone. Our results suggest that the blue light signal is sensed by stomata of expanded leaves and transduced to the leaf growth zone through the hydraulic architecture of the tiller.
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Affiliation(s)
| | - Tom De Swaef
- Plant Sciences Unit, Institute for Agricultural and Fisheries Research (ILVO), Melle, Belgium
| | | | | | | | - Pierre Martre
- INRAE, Univ Montpellier, Montpellier SupAgro, UMR LEPSE, Montpellier, France
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4
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Baca Cabrera JC, Hirl RT, Zhu J, Schäufele R, Schnyder H. Atmospheric CO 2 and VPD alter the diel oscillation of leaf elongation in perennial ryegrass: compensation of hydraulic limitation by stored-growth. THE NEW PHYTOLOGIST 2020; 227:1776-1789. [PMID: 32369620 DOI: 10.1111/nph.16639] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 04/26/2020] [Indexed: 06/11/2023]
Abstract
We explored the effects of atmospheric CO2 concentration (Ca ) and vapor pressure deficit (VPD) on putative mechanisms controlling leaf elongation in perennial ryegrass. Plants were grown in stands at a Ca of 200, 400 or 800 μmol mol-1 combined with high (1.17 kPa) or low (0.59 kPa) VPD during the 16 h-day in well-watered conditions with reduced nitrogen supply. We measured day : night-variation of leaf elongation rate (LERday : LERnight ), final leaf length and width, epidermal cell number and length, stomatal conductance, transpiration, leaf water potential and water-soluble carbohydrates and osmotic potential in the leaf growth-and-differentiation zone (LGDZ). Daily mean LER or morphometric parameters did not differ between treatments, but LERnight strongly exceeded LERday , particularly at low Ca and high VPD. Across treatments LERday was negatively related to transpiration (R2 = 0.75) and leaf water potential (R2 = 0.81), while LERnight was independent of leaf water potential or turgor. Enhancement of LERnight over LERday was proportional to the turgor-change between day and night (R2 = 0.93). LGDZ sugar concentration was high throughout diel cycles, providing no evidence of source limitation in any treatment. Our data indicate a mechanism of diel cycling between daytime hydraulic and night-time stored-growth controls of LER, buffering Ca and daytime VPD effects on leaf elongation.
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Affiliation(s)
- Juan C Baca Cabrera
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, Freising-Weihenstephan, 85354, Germany
| | - Regina T Hirl
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, Freising-Weihenstephan, 85354, Germany
| | - Jianjun Zhu
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, Freising-Weihenstephan, 85354, Germany
| | - Rudi Schäufele
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, Freising-Weihenstephan, 85354, Germany
| | - Hans Schnyder
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, Freising-Weihenstephan, 85354, Germany
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5
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Dalmannsdottir S, Jørgensen M, Rapacz M, Østrem L, Larsen A, Rødven R, Rognli OA. Cold acclimation in warmer extended autumns impairs freezing tolerance of perennial ryegrass (Lolium perenne) and timothy (Phleum pratense). PHYSIOLOGIA PLANTARUM 2017; 160:266-281. [PMID: 28144950 DOI: 10.1111/ppl.12548] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 12/21/2016] [Accepted: 01/18/2017] [Indexed: 05/11/2023]
Abstract
The effect of variable autumn temperatures in combination with decreasing irradiance and daylength on photosynthesis, growth cessation and freezing tolerance was investigated in northern- and southern-adapted populations of perennial ryegrass (Lolium perenne) and timothy (Phleum pratense) intended for use in regions at northern high latitudes. Plants were subjected to three different acclimation temperatures; 12, 6 and 9/3°C (day/night) for 4 weeks, followed by 1 week of cold acclimation at 2°C under natural light conditions. This experimental setup was repeated at three different periods during autumn with decreasing sums of irradiance and daylengths. Photoacclimation, leaf elongation and freezing tolerance were studied. The results showed that plants cold acclimated during the period with lowest irradiance and shortest day had lowest freezing tolerance, lowest photosynthetic activity, longest leaves and least biomass production. Higher acclimation temperature (12°C) resulted in lower freezing tolerance, lower photosynthetic activity, faster leaf elongation rate and higher biomass compared with the other temperatures. Photochemical mechanisms were predominant in photoacclimation. The northern-adapted populations had a better freezing tolerance than the southern-adapted except when grown during the late autumn period and at the highest temperature; then there were no differences between the populations. Our results indicate that the projected climate change in the north may reduce freezing tolerance in grasses as acclimation will take place at higher temperatures and shorter daylengths with lower irradiance.
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Affiliation(s)
- Sigridur Dalmannsdottir
- Department of Grassland and Livestock, Norwegian Institute of Bioeconomy Research, Holt, 9016 Tromsø, Norway
- Department of Plant Sciences, Faculty of Biosciences, Norwegian University of Life Sciences, 1432, Ås
| | - Marit Jørgensen
- Department of Grassland and Livestock, Norwegian Institute of Bioeconomy Research, Holt, 9016 Tromsø, Norway
| | - Marcin Rapacz
- Department of Plant Physiology, University of Agriculture in Krakow, 30-239, Krakow, Poland
| | - Liv Østrem
- Department of Grassland and Livestock, Norwegian Institute of Bioeconomy Research, Fureneset, 6967, Hellevik i Fjaler, Norway
| | - Arild Larsen
- Graminor AS, Bjørke gård, Hommelstadvegen 60, 2322, Ridabu, Norway
| | - Rolf Rødven
- Department of Grassland and Livestock, Norwegian Institute of Bioeconomy Research, Holt, 9016 Tromsø, Norway
- Faculty of Bioscience, Fisheries and Economics, UiT - The Arctic University of Norway, Tromsø, 9037, Norway
| | - Odd Arne Rognli
- Department of Plant Sciences, Faculty of Biosciences, Norwegian University of Life Sciences, 1432, Ås
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6
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Liu HT, Schäufele R, Gong XY, Schnyder H. The δ 18 O and δ 2 H of water in the leaf growth-and-differentiation zone of grasses is close to source water in both humid and dry atmospheres. THE NEW PHYTOLOGIST 2017; 214:1423-1431. [PMID: 28369914 DOI: 10.1111/nph.14549] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2017] [Accepted: 03/06/2017] [Indexed: 06/07/2023]
Abstract
The oxygen and hydrogen isotope composition of water in the leaf growth-and-differentiation zone, LGDZ, (δ18 OLGDZ , δ2 HLGDZ ) of grasses influences the isotopic composition of leaf cellulose (oxygen) and wax (hydrogen) - important for understanding (paleo)environmental and physiological information contained in these biological archives - but is presently unknown. This work determined δ18 OLGDZ and δ2 HLGDZ , 18 O- and 2 H-enrichment of LGDZ (∆18 OLGDZ and ∆2 HLGDZ ), and the 18 O- and 2 H-enrichment of leaf blade water (∆18 OLW, ∆2 HLW ) in two C3 and three C4 grasses grown at high and low vapor pressure deficit (VPD). The proportion of unenriched water (px ) in the LGDZ ranged from 0.9 to 1.0 for 18 O and 1.0 to 1.2 for 2 H. VPD had no effect on the proportion of 18 O- and 2 H-enriched water in the LGDZ, and species effects were small or nonsignificant. Deuterium discrimination caused depletion of 2 H in LGDZ water, increasing (apparent) px -values > 1.0 in some cases. The isotopic composition of water in the LGDZ was close to that of source water, independent of VPD and much less enriched than previously supposed, but similar to reported xylem water in trees. The well-constrained px will be useful in future investigations of oxygen and hydrogen isotopic fractionation during cellulose and wax synthesis, respectively.
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Affiliation(s)
- Hai Tao Liu
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, 85354, Freising-Weihenstephan, Germany
| | - Rudi Schäufele
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, 85354, Freising-Weihenstephan, Germany
| | - Xiao Ying Gong
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, 85354, Freising-Weihenstephan, Germany
| | - Hans Schnyder
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, 85354, Freising-Weihenstephan, Germany
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7
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Sprangers K, Avramova V, Beemster GTS. Kinematic Analysis of Cell Division and Expansion: Quantifying the Cellular Basis of Growth and Sampling Developmental Zones in Zea mays Leaves. J Vis Exp 2016:54887. [PMID: 28060300 PMCID: PMC5226352 DOI: 10.3791/54887] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Growth analyses are often used in plant science to investigate contrasting genotypes and the effect of environmental conditions. The cellular aspect of these analyses is of crucial importance, because growth is driven by cell division and cell elongation. Kinematic analysis represents a methodology to quantify these two processes. Moreover, this technique is easy to use in non-specialized laboratories. Here, we present a protocol for performing a kinematic analysis in monocotyledonous maize (Zea mays) leaves. Two aspects are presented: (1) the quantification of cell division and expansion parameters, and (2) the determination of the location of the developmental zones. This could serve as a basis for sampling design and/or could be useful for data interpretation of biochemical and molecular measurements with high spatial resolution in the leaf growth zone. The growth zone of maize leaves is harvested during steady-state growth. Individual leaves are used for meristem length determination using a DAPI stain and cell-length profiles using DIC microscopy. The protocol is suited for emerged monocotyledonous leaves harvested during steady-state growth, with growth zones spanning at least several centimeters. To improve the understanding of plant growth regulation, data on growth and molecular studies must be combined. Therefore, an important advantage of kinematic analysis is the possibility to correlate changes at the molecular level to well-defined stages of cellular development. Furthermore, it allows for a more focused sampling of specified developmental stages, which is useful in case of limited budget or time.
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8
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Liu HT, Gong XY, Schäufele R, Yang F, Hirl RT, Schmidt A, Schnyder H. Nitrogen fertilization and δ 18 O of CO 2 have no effect on 18 O-enrichment of leaf water and cellulose in Cleistogenes squarrosa (C 4 ) - is VPD the sole control? PLANT, CELL & ENVIRONMENT 2016; 39:2701-2712. [PMID: 27576868 DOI: 10.1111/pce.12824] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 08/23/2016] [Accepted: 08/24/2016] [Indexed: 06/06/2023]
Abstract
The oxygen isotope composition of cellulose (δ18 OCel ) archives hydrological and physiological information. Here, we assess previously unexplored direct and interactive effects of the δ18 O of CO2 (δ18 OCO2 ), nitrogen (N) fertilizer supply and vapour pressure deficit (VPD) on δ18 OCel , 18 O-enrichment of leaf water (Δ18 OLW ) and cellulose (Δ18 OCel ) relative to source water, and pex px , the proportion of oxygen in cellulose that exchanged with unenriched water at the site of cellulose synthesis, in a C4 grass (Cleistogenes squarrosa). δ18 OCO2 and N supply, and their interactions with VPD, had no effect on δ18 OCel , Δ18 OLW , Δ18 OCel and pex px . Δ18 OCel and Δ18 OLW increased with VPD, while pex px decreased. That VPD-effect on pex px was supported by sensitivity tests to variation of Δ18 OLW and the equilibrium fractionation factor between carbonyl oxygen and water. N supply altered growth and morphological features, but not 18 O relations; conversely, VPD had no effect on growth or morphology, but controlled 18 O relations. The work implies that reconstructions of VPD from Δ18 OCel would overestimate amplitudes of VPD variation, at least in this species, if the VPD-effect on pex px is ignored. Progress in understanding the relationship between Δ18 OLW and Δ18 OCel will require separate investigations of pex and px and of their responses to environmental conditions.
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Affiliation(s)
- Hai Tao Liu
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, 85354, Freising, Germany
| | - Xiao Ying Gong
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, 85354, Freising, Germany
| | - Rudi Schäufele
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, 85354, Freising, Germany
| | - Fang Yang
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, 85354, Freising, Germany
| | - Regina Theresia Hirl
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, 85354, Freising, Germany
| | - Anja Schmidt
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, 85354, Freising, Germany
| | - Hans Schnyder
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, 85354, Freising, Germany
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Caldeira CF, Bosio M, Parent B, Jeanguenin L, Chaumont F, Tardieu F. A hydraulic model is compatible with rapid changes in leaf elongation under fluctuating evaporative demand and soil water status. PLANT PHYSIOLOGY 2014; 164:1718-30. [PMID: 24420931 PMCID: PMC3982736 DOI: 10.1104/pp.113.228379] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Accepted: 12/22/2013] [Indexed: 05/03/2023]
Abstract
Plants are constantly facing rapid changes in evaporative demand and soil water content, which affect their water status and growth. In apparent contradiction to a hydraulic hypothesis, leaf elongation rate (LER) declined in the morning and recovered upon soil rehydration considerably quicker than transpiration rate and leaf water potential (typical half-times of 30 min versus 1-2 h). The morning decline of LER began at very low light and transpiration and closely followed the stomatal opening of leaves receiving direct light, which represent a small fraction of leaf area. A simulation model in maize (Zea mays) suggests that these findings are still compatible with a hydraulic hypothesis. The small water flux linked to stomatal aperture would be sufficient to decrease water potentials of the xylem and growing tissues, thereby causing a rapid decline of simulated LER, while the simulated water potential of mature tissues declines more slowly due to a high hydraulic capacitance. The model also captured growth patterns in the evening or upon soil rehydration. Changes in plant hydraulic conductance partly counteracted those of transpiration. Root hydraulic conductivity increased continuously in the morning, consistent with the transcript abundance of Zea maize Plasma Membrane Intrinsic Protein aquaporins. Transgenic lines underproducing abscisic acid, with lower hydraulic conductivity and higher stomatal conductance, had a LER declining more rapidly than wild-type plants. Whole-genome transcriptome and phosphoproteome analyses suggested that the hydraulic processes proposed here might be associated with other rapidly occurring mechanisms. Overall, the mechanisms and model presented here may be an essential component of drought tolerance in naturally fluctuating evaporative demand and soil moisture.
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Affiliation(s)
- Cecilio F. Caldeira
- INRA, Unité Mixte de Recherche 759 Laboratoire d’Ecophysiologie des Plantes sous Stress Environnementaux, F–34060 Montpellier, France (C.F.C., B.P., F.T.)
- Biogemma, 63028 Clermont-Ferrand cedex 2, France (M.B.); and
- Institut des Sciences de la Vie, Université Catholique de Louvain, B–1348 Louvain-la-Neuve, Belgium (L.J., F.C.)
| | - Mickael Bosio
- INRA, Unité Mixte de Recherche 759 Laboratoire d’Ecophysiologie des Plantes sous Stress Environnementaux, F–34060 Montpellier, France (C.F.C., B.P., F.T.)
- Biogemma, 63028 Clermont-Ferrand cedex 2, France (M.B.); and
- Institut des Sciences de la Vie, Université Catholique de Louvain, B–1348 Louvain-la-Neuve, Belgium (L.J., F.C.)
| | - Boris Parent
- INRA, Unité Mixte de Recherche 759 Laboratoire d’Ecophysiologie des Plantes sous Stress Environnementaux, F–34060 Montpellier, France (C.F.C., B.P., F.T.)
- Biogemma, 63028 Clermont-Ferrand cedex 2, France (M.B.); and
- Institut des Sciences de la Vie, Université Catholique de Louvain, B–1348 Louvain-la-Neuve, Belgium (L.J., F.C.)
| | - Linda Jeanguenin
- INRA, Unité Mixte de Recherche 759 Laboratoire d’Ecophysiologie des Plantes sous Stress Environnementaux, F–34060 Montpellier, France (C.F.C., B.P., F.T.)
- Biogemma, 63028 Clermont-Ferrand cedex 2, France (M.B.); and
- Institut des Sciences de la Vie, Université Catholique de Louvain, B–1348 Louvain-la-Neuve, Belgium (L.J., F.C.)
| | - François Chaumont
- INRA, Unité Mixte de Recherche 759 Laboratoire d’Ecophysiologie des Plantes sous Stress Environnementaux, F–34060 Montpellier, France (C.F.C., B.P., F.T.)
- Biogemma, 63028 Clermont-Ferrand cedex 2, France (M.B.); and
- Institut des Sciences de la Vie, Université Catholique de Louvain, B–1348 Louvain-la-Neuve, Belgium (L.J., F.C.)
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10
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Kravchik M, Bernstein N. Effects of salinity on the transcriptome of growing maize leaf cells point at cell-age specificity in the involvement of the antioxidative response in cell growth restriction. BMC Genomics 2013; 14:24. [PMID: 23324477 PMCID: PMC3599246 DOI: 10.1186/1471-2164-14-24] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 12/18/2012] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Salinity inhibits growth and development of most plants. The response to salinity is complex and varies between plant organs and stages of development. It involves challenges of ion toxicities and deficiencies as well as osmotic and oxidative stresses. The range of functions affected by the stress is reflected in elaborate changes to the transcriptome. The mechanisms involved in the developmental-stage specificity of the inhibitory responses are not fully understood. The present study took advantage of the well characterized developmental progression that exists along the maize leaf, for identification of salinity induced, developmentally-associated changes to the transcriptome. Differential subtraction screening was conducted for cells of two developmental stages: from the center of the growth zone where the expansion rate is highest, and from older cells at a more distal location of the growing zone where the expansion rate is lower and the salinity restrictive effects are more pronounced. Real-Time PCR analysis was used for validation of the expression of selected genes. RESULTS The salinity-induced changes demonstrated an age-related response of the growing tissue, with elevation of salinity-damages with increased age. Growth reduction, similar to the elevation of percentage dry matter (%DM), and Na and Cl concentrations were more pronounced in the older cells. The differential subtraction screening identified genes encoding to proteins involved in antioxidant defense, electron transfer and energy, structural proteins, transcription factors and photosynthesis proteins. Of special interest is the higher induced expression of genes involved in antioxidant protection in the young compared to older cells, which was accompanied by suppressed levels of reactive oxygen species (H2O2 and O2-). This was coupled with heightened expression in the older cells of genes that enhance cell-wall rigidity, which points at reduced potential for cell expansion. CONCLUSIONS The results demonstrate a cell-age specificity in the salinity response of growing cells, and point at involvement of the antioxidative response in cell growth restriction. Processes involved in reactive oxygen species (ROS) scavenging are more pronounced in the young cells, while the higher growth sensitivity of older cells is suggested to involve effects on cell-wall rigidity and lower protein protection.
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Affiliation(s)
- Michael Kravchik
- Institute of Soil Water and Environmental Sciences, Volcani Center, POB 6, 50-250, Bet-Dagan, Israel
| | - Nirit Bernstein
- Institute of Soil Water and Environmental Sciences, Volcani Center, POB 6, 50-250, Bet-Dagan, Israel
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11
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Ruts T, Matsubara S, Wiese-Klinkenberg A, Walter A. Diel patterns of leaf and root growth: endogenous rhythmicity or environmental response? JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:3339-51. [PMID: 22223810 DOI: 10.1093/jxb/err334] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Plants are sessile organisms forced to adjust to their surrounding environment. In a single plant the photoautotrophic shoot is exposed to pronounced environmental variations recurring in a day-night 24 h (diel) cycle, whereas the heterotrophic root grows in a temporally less fluctuating environment. The contrasting habitats of shoots and roots are reflected in different diel growth patterns and their responsiveness to environmental stimuli. Differences between diel leaf growth patterns of mono- and dicotyledonous plants correspond to their different organization and placement of growth zones. In monocots, heterotrophic growth zones are organized linearly and protected from the environment by sheaths of older leaves. In contrast, photosynthetically active growth zones of dicot leaves are exposed directly to the environment and show characteristic, species-specific diel growth patterns. It is hypothesized that the different exposure to environmental constraints and simultaneously the sink/source status of the growing organs may have induced distinct endogenous control of diel growth patterns in roots and leaves of monocot and dicot plants. Confronted by strong temporal fluctuations in environment, the circadian clock may facilitate robust intrinsic control of leaf growth in dicot plants.
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Affiliation(s)
- Tom Ruts
- Forschungszentrum Jülich, IBG-2: Plant Sciences, Wilhelm-Johnen-Strasse, Jülich, Germany
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Pantin F, Simonneau T, Rolland G, Dauzat M, Muller B. Control of leaf expansion: a developmental switch from metabolics to hydraulics. PLANT PHYSIOLOGY 2011; 156:803-15. [PMID: 21474437 PMCID: PMC3177277 DOI: 10.1104/pp.111.176289] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2011] [Accepted: 04/04/2011] [Indexed: 05/18/2023]
Abstract
Leaf expansion is the central process by which plants colonize space, allowing energy capture and carbon acquisition. Water and carbon emerge as main limiting factors of leaf expansion, but the literature remains controversial about their respective contributions. Here, we tested the hypothesis that the importance of hydraulics and metabolics is organized according to both dark/light fluctuations and leaf ontogeny. For this purpose, we established the developmental pattern of individual leaf expansion during days and nights in the model plant Arabidopsis (Arabidopsis thaliana). Under control conditions, decreases in leaf expansion were observed at night immediately after emergence, when starch reserves were lowest. These nocturnal decreases were strongly exaggerated in a set of starch mutants, consistent with an early carbon limitation. However, low-light treatment of wild-type plants had no influence on these early decreases, implying that expansion can be uncoupled from changes in carbon availability. From 4 d after leaf emergence onward, decreases of leaf expansion were observed in the daytime. Using mutants impaired in stomatal control of transpiration as well as plants grown under soil water deficit or high air humidity, we gathered evidence that these diurnal decreases were the signature of a hydraulic limitation that gradually set up as the leaf developed. Changes in leaf turgor were consistent with this pattern. It is concluded that during the course of leaf ontogeny, the predominant control of leaf expansion switches from metabolics to hydraulics. We suggest that the leaf is better armed to buffer variations in the former than in the latter.
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Affiliation(s)
| | | | | | | | - Bertrand Muller
- Laboratoire d’Ecophysiologie des Plantes sous Stress Environnementaux, UMR759, Institut de Biologie Intégrative des Plantes, INRA, 34060 Montpellier, France
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13
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Tardieu F, Parent B, Simonneau T. Control of leaf growth by abscisic acid: hydraulic or non-hydraulic processes? PLANT, CELL & ENVIRONMENT 2010; 33:636-47. [PMID: 20002334 DOI: 10.1111/j.1365-3040.2009.02091.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Abscisic acid (ABA) affects plant metabolism and water transfers via multiple mechanisms at cell, organ and whole plant levels. These mechanisms translate into contradictory effects on leaf growth, so the literature reports positive, null or negative effects of ABA on leaf growth upon water deficit. We review evidences based on genetic manipulations of ABA biosynthesis, feeding the plant with artificial ABA or partial root drying and provide elements to avoid confusions of effects. We propose that ABA has mainly three effects on growth. (i) Via its controlling effect on stomatal aperture and transpiration rate, an increased concentration of ABA tends to buffer the day-night alternations of leaf growth rate and the negative effect of evaporative demand. (ii) ABA tends to improve leaf growth via an increase in the conductance to water transfer in the plant as a result of increased tissue hydraulic conductivity. (iii) ABA has also a modest non-hydraulic effect which is negative in plants subjected to water deficit, either manipulated for ABA synthesis or fed with artificial ABA, but can be positive in well watered plants deficient of ABA. The overall effect of increasing ABA biosynthesis depends on the relative weight of each of these effects under different environmental scenarios.
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Affiliation(s)
- François Tardieu
- INRA, UMR Laboratoire d'Ecophysiologie des Plantes sous Stress Environnementaux, Montpellier, France
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14
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Poiré R, Schneider H, Thorpe MR, Kuhn AJ, Schurr U, Walter A. Root cooling strongly affects diel leaf growth dynamics, water and carbohydrate relations in Ricinus communis. PLANT, CELL & ENVIRONMENT 2010; 33:408-417. [PMID: 19968824 DOI: 10.1111/j.1365-3040.2009.02090.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In laboratory and greenhouse experiments with potted plants, shoots and roots are exposed to temperature regimes throughout a 24 h (diel) cycle that can differ strongly from the regime under which these plants have evolved. In the field, roots are often exposed to lower temperatures than shoots. When the root-zone temperature in Ricinus communis was decreased below a threshold value, leaf growth occurred preferentially at night and was strongly inhibited during the day. Overall, leaf expansion, shoot biomass growth, root elongation and ramification decreased rapidly, carbon fluxes from shoot to root were diminished and carbohydrate contents of both root and shoot increased. Further, transpiration rate was not affected, yet hydrostatic tensions in shoot xylem increased. When root temperature was increased again, xylem tension reduced, leaf growth recovered rapidly, carbon fluxes from shoot to root increased, and carbohydrate pools were depleted. We hypothesize that the decreased uptake of water in cool roots diminishes the growth potential of the entire plant - especially diurnally, when the growing leaf loses water via transpiration. As a consequence, leaf growth and metabolite concentrations can vary enormously, depending on root-zone temperature and its heterogeneity inside pots.
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Affiliation(s)
- Richard Poiré
- Institut Phytosphere (ICG-3), Forschungszentrum Jülich GmbH, Jülich, Germany
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15
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Taleisnik E, Rodríguez AA, Bustos D, Erdei L, Ortega L, Senn ME. Leaf expansion in grasses under salt stress. JOURNAL OF PLANT PHYSIOLOGY 2009; 166:1123-40. [PMID: 19467732 DOI: 10.1016/j.jplph.2009.03.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Revised: 03/29/2009] [Accepted: 03/29/2009] [Indexed: 05/18/2023]
Abstract
Restriction of leaf growth is among the earliest visible effects of many stress conditions, including salinity. Because leaves determine radiation interception and are the main photosynthetic organs, salinity effects on leaf expansion and function are directly related to yield constraints under saline conditions. The expanding zone of leaf blades spans from the meristem to the region in which cells reach their final length. Kinematic methods are used to describe cell division and cell expansion activities. Analyses of this type have indicated that the reduction in leaf expansion by salinity may be exerted through effects on both cell division and expansion. In turn, the components of vacuole-driven cell expansion may be differentially affected by salinity, and examination of salinity effects on osmotic and mechanical constraints to cell expansion have gradually led to the identification of the gene products involved in such control. The study of how reactive oxygen species affect cell expansion is an emerging topic in the study of salinity's regulation of leaf growth.
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Affiliation(s)
- Edith Taleisnik
- CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina), Argentina.
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16
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Walter A, Silk WK, Schurr U. Environmental effects on spatial and temporal patterns of leaf and root growth. ANNUAL REVIEW OF PLANT BIOLOGY 2009; 60:279-304. [PMID: 19575584 DOI: 10.1146/annurev.arplant.59.032607.092819] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Leaves and roots live in dramatically different habitats, but are parts of the same organism. Automated image processing of time-lapse records of these organs has led to understanding of spatial and temporal patterns of growth on time scales from minutes to weeks. Growth zones in roots and leaves show distinct patterns during a diel cycle (24 h period). In dicot leaves under nonstressful conditions these patterns are characterized by endogenous rhythms, sometimes superimposed upon morphogenesis driven by environmental variation. In roots and monocot leaves the growth patterns depend more strongly on environmental fluctuations. Because the impact of spatial variations and temporal fluctuations of above- and belowground environmental parameters must be processed by the plant body as an entire system whose individual modules interact on different levels, growth reactions of individual modules are often highly nonlinear. A mechanistic understanding of plant resource use efficiency and performance in a dynamically fluctuating environment therefore requires an accurate analysis of leaf and root growth patterns in conjunction with knowledge of major intraplant communication systems and metabolic pathways.
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Affiliation(s)
- Achim Walter
- Institute of Chemistry and Dynamics of Geosphere ICG-3: Phytosphere Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
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Kavanová M, Lattanzi FA, Schnyder H. Nitrogen deficiency inhibits leaf blade growth in Lolium perenne by increasing cell cycle duration and decreasing mitotic and post-mitotic growth rates. PLANT, CELL & ENVIRONMENT 2008; 31:727-37. [PMID: 18208511 DOI: 10.1111/j.1365-3040.2008.01787.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Nitrogen deficiency severely inhibits leaf growth. This response was analysed at the cellular level by growing Lolium perenne L. under 7.5 mM (high) or 1 mM (low) nitrate supply, and performing a kinematic analysis to assess the effect of nitrogen status on cell proliferation and cell growth in the leaf blade epidermis. Low nitrogen supply reduced leaf elongation rate (LER) by 43% through a similar decrease in the cell production rate and final cell length. The former was entirely because of a decreased average cell division rate (0.023 versus 0.032 h(-1)) and thus longer cell cycle duration (30 versus 22 h). Nitrogen status did not affect the number of division cycles of the initial cell's progeny (5.7), and accordingly the meristematic cell number (53). Meristematic cell length was unaffected by nitrogen deficiency, implying that the division and mitotic growth rates were equally impaired. The shorter mature cell length arose from a considerably reduced post-mitotic growth rate (0.033 versus 0.049 h(-1)). But, nitrogen stress did not affect the position where elongation stopped, and increased cell elongation duration. In conclusion, nitrogen deficiency limited leaf growth by increasing the cell cycle duration and decreasing mitotic and post-mitotic elongation rates, delaying cell maturation.
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Affiliation(s)
- Monika Kavanová
- Lehrstuhl für Grünlandlehre, Technische Universität München, Am Hochanger 1, D-85350 Freising, Weihenstephan, Germany
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18
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Bouchabké O, Tardieu F, Simonneau T. Leaf growth and turgor in growing cells of maize (Zea mays L.) respond to evaporative demand under moderate irrigation but not in water-saturated soil. PLANT, CELL & ENVIRONMENT 2006; 29:1138-48. [PMID: 17080939 DOI: 10.1111/j.1365-3040.2005.01494.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
To test whether the inhibition of leaf expansion by high evaporative demand is a result of hydraulic processes, we have followed both leaf elongation rate (LER) and cell turgor in leaves of maize plants either normally watered or in water-saturated soil in which hydraulic resistance at the soil-root interface was abolished. Cell turgor was measured in situ with a pressure probe in the elongating zone of the first and sixth leaves, and LERs of the same leaves were measured continuously with transducers or by following displacements of marks along the growing leaves. Both variables displayed spatial variations along the leaf and positively correlated within the elongating zone. Values peaked at mid-distance of this zone, where the response of turgor to evaporative demand was further dissected. High evaporative demand decreased both LER and turgor for at least 5 h, with dose-effect linear relations. This was observed in five genotypes with appreciable differences in turgor maintenance among genotypes. In contrast, the depressing effects of evaporative demand on both turgor and LER disappeared when the soil was saturated, thereby opposing a negligible resistance to water flow at the soil-root interface. These results suggest that the response of LER to evaporative demand has a hydraulic origin, enhanced by the resistance to water flux at the soil-root interface. They also suggest that turgor is not completely maintained under high evaporative demand, and may therefore contribute to the reductions in LER observed in non-saturated soils.
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Affiliation(s)
- Oumaya Bouchabké
- Laboratoire d'Ecophysiologie des Plantes sous Stress Environnementaux, UMR Institut National de la Recherche Agronomique, Ecole Nationale Supérieure d'Agronomie de Montpellier, F- 34060 Montpellier 1, France
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19
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Kavanová M, Grimoldi AA, Lattanzi FA, Schnyder H. Phosphorus nutrition and mycorrhiza effects on grass leaf growth. P status- and size-mediated effects on growth zone kinematics. PLANT, CELL & ENVIRONMENT 2006; 29:511-20. [PMID: 17080603 DOI: 10.1111/j.1365-3040.2005.01428.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
This study tested whether leaf elongation rate (LER, mm h(-1)) and its components--average relative elemental growth rate (REGRavg, mm mm(-1) h(-1)) and leaf growth zone length (L(LGZ), mm)--are related to phosphorus (P) concentration in the growth zone (P(LGZ) mg P g(-1) tissue water) of Lolium perenne L. cv. Condesa and whether such relationships are modified by the arbuscular mycorrhizal fungus (AMF) Glomus hoi. Mycorrhizal and non-mycorrhizal plants were grown at a range of P supply rates and analysed at either the same plant age or the same tiller size (defined by the length of the sheath of the youngest fully expanded leaf). Both improved P supply (up to 95%) and AMF (up to 21%) strongly increased LER. In tillers of even-aged plants, this was due to increased REGRavg and L(LGZ). In even-sized tillers, it was exclusively due to increased REGRavg. REGRavg was strictly related to P(LGZ) (r2 = 0.95) and independent of tiller size. Conversely, L(LGZ) strictly depended on tiller size (r2 = 0.88) and not on P(LGZ). Hence, P status affected leaf growth directly only through effects on relative tissue expansion rates. Symbiosis with AMF did not modify these relationships. Thus, no evidence for P status-independent effects of AMF on LER was found.
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Affiliation(s)
- Monika Kavanová
- Lehrstuhl für Grünlandlehre, Technische Universität München, Am Hochanger 1, D-85350 Freising-Weihenstephan, Germany
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20
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COOKSON SARAHJANE, GRANIER CHRISTINE. A dynamic analysis of the shade-induced plasticity in Arabidopsis thaliana rosette leaf development reveals new components of the shade-adaptative response. ANNALS OF BOTANY 2006; 97:443-52. [PMID: 16371443 PMCID: PMC2803649 DOI: 10.1093/aob/mcj047] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
BACKGROUND AND AIMS It is well known that plant aerial development is affected by light intensity in terms of the date of flowering, the length of stems and petioles, and the final individual leaf area. The aim of the work presented here was to analyse how shade-induced changes in leaf development occur on a dynamic basis from the whole rosette level to that of the cells. METHODS Care was taken to ensure that light intensity was the only source of micro-meteorological variation in the study. The dynamics of leaf production, rosette expansion, individual leaf area expansion and epidermal cell expansion were analysed in Arabidopsis thaliana plants grown under two light intensities in three independent experiments. KEY RESULTS The total area of rosette leaves was reduced by the shading treatment. Both the number of leaves produced and their individual leaf areas were reduced. The reduction in leaf number was associated with a reduction in leaf initiation rate and the duration of the phase of leaf production. The reduction in individual leaf area was associated with a reduction in leaf expansion rate and an increase in the duration of leaf expansion. The changes in leaf expansion dynamics were accompanied by a decrease in epidermal cell number which was partly compensated for by an increase in epidermal cell area. Overall, the whole rosette leaf expansion rate was reduced by shading, whereas the total duration of rosette leaf expansion was unaffected. This was mainly due to the accumulation of the increases in the durations of expansion of each individual leaf which was associated with an increase in cell expansion. CONCLUSIONS The dynamic analysis presented here reveals a new shade-adaptative response mediated via the control of area expansion at the cell, organ and whole plant levels.
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Neves-Piestun BG, Bernstein N. Salinity-induced changes in the nutritional status of expanding cells may impact leaf growth inhibition in maize. FUNCTIONAL PLANT BIOLOGY : FPB 2005; 32:141-152. [PMID: 32689118 DOI: 10.1071/fp04113] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2004] [Accepted: 10/28/2004] [Indexed: 05/27/2023]
Abstract
Salinity-induced excess or deficiency of specific nutrients are often hypothesised to operate as causes of growth inhibition and to trigger primary responses, which directly affect growth. Information concerning salinity effects on microelement nutrition in the growing cells is limited. In this study, salinity-(80 mm NaCl) inflicted alterations in spatial profiles of essential elements (N, P, K, S, Ca, Mg, Fe, Zn, Mn, Cu) and the salinity source (Na and Cl) were studied along the growing zone of leaf 4 of maize (Zea mays L.). Correlations between spatial profiles of growth and nutritional status of the tissue were tested for evaluation of the hypothesis that a disturbance of specific mineral nutritional factors in the growing cells might serve as causes of salt-induced growth inhibition. Examined nutritional elements exhibited unique distribution patterns, all of which were disturbed by salinity. With the exception of Na, Cl and Fe, the deposition rates of all the studied mineral elements were reduced by salinity throughout the elongating tissue. Localised contents of Ca, K and Fe in the growing tissue of the salt-stressed leaf were highly correlated with the intensity of localised tissue volumetric expansion, suggesting reduced levels of Ca and K, and toxic levels of Fe as possible causes of growth inhibition. Na and Cl accumulation were not correlated with growth inhibition under salinity.
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Affiliation(s)
- Beatriz G Neves-Piestun
- Institute of Soil, Water and Environmental Sciences, Agricultural Research Organization, The Volcani Center, PO Box 6, Bet-Dagan 50-250, Israel
| | - Nirit Bernstein
- Institute of Soil, Water and Environmental Sciences, Agricultural Research Organization, The Volcani Center, PO Box 6, Bet-Dagan 50-250, Israel
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Ortega L, Taleisnik E. Elongation growth in leaf blades of Chloris gayana under saline conditions. JOURNAL OF PLANT PHYSIOLOGY 2003; 160:517-522. [PMID: 12806780 DOI: 10.1078/0176-1617-00827] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In Chloris gayana, salinity-associated yield decreases are due mainly to leaf area reductions. To understand the physiological basis for such reduction, the effects of salinity were studied on the spatial and temporal distribution of extension in the intercalary meristem at the leaf base, and on hydraulic conductance in that zone. C. gayana plants were grown on sand irrigated with Hoagland solution with the addition of 0 or 200 mmol/L NaCl, and all measurements were performed on tiller leaf four. In salinised plants, that leaf was 20% shorter than in controls. Extension in the blade expansion zone was studied by pricking through the leaf sheaths and analysing the displacement of the pricks. In salt-treated plants, maximum growth rates were depressed by 53% and the growth zone was shorter by approximately 10 mm, nevertheless, extension proceeded for a longer period than in control plants. The analysis of specific leaf areas in the expansion zone suggests the rate of dry matter deposition was lowered by salinity and estimations of tissue displacement time within that zone suggest cell wall maturity was delayed. Hydraulic conductance was reduced by salinity and this may be the main cause for reduced growth under salinity in Chloris gayana.
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Affiliation(s)
- Leandro Ortega
- Instituto de Fitopatología y Fisiología Vegetal, INTA, Camino a 60 Cuadras Km 5 1/2, 5119 Córdoba, Argentina
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Macduff JH, Bakken AK. Diurnal variation in uptake and xylem contents of inorganic and assimilated N under continuous and interrupted N supply to Phleum pratense and Festuca pratensis. JOURNAL OF EXPERIMENTAL BOTANY 2003; 54:431-444. [PMID: 12493871 DOI: 10.1093/jxb/erg058] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Compensation by dark-period uptake of NH(4)(+) and NO(3)(-) in the grasses Phleum pratense L. and Festuca pratensis Huds. following N deprivation during the preceding light period was investigated in flowing solution culture under an artificial 10/14 h light/dark cycle. N was supplied as either NO(3)(-), NH(4)(+) or NH(4)NO(3) at 20+/-5 mmol m(-3), available continuously or only during the dark period, for 5-10 d. Intermittent N supply did not affect total daily N uptake, growth rate or net partitioning of dry matter. Net uptake and influx of NO(3)(-) varied similarly throughout the diurnal cycle when NO(3)(-) was supplied continuously, with a marginal contribution by NO(3)(-) efflux. Influx was significantly higher and efflux slightly higher following interruption of NO(3)(-) supply during the light period. Nitrate accounted for 80% of N in xylem exudate except between hours 6-9 of the light period when the amino acid concentration increased 3-fold, primarily as glutamine. Diurnal variation in relative NO(3)(-) uptake exhibited five phases of constant acceleration/deceleration, described reasonably well assuming NO(3)(-) influx was subject to metabolic co-regulation by NO(3)(-) and amino acid levels in the cytoplasmic compartment of the roots. Accordingly, influx is determined by variation in root NO(3)(-) levels throughout the dark period and the first half of the light period, but is down-regulated by increased amino acid levels during the second half of the light period. The sharp light/dark transitions affect transpiration rate and hence xylem N flux which, in turn, affect NO(3)(-) levels in the cytoplasmic compartment of the roots and the rate of NO(3)(-) assimilation in the shoot.
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Affiliation(s)
- J H Macduff
- Institute of Grassland and Environmental Research, Aberystwyth Research Centre, Aberystwyth SY23 3EB, UK.
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Macadam JW, Nelson CJ. Secondary cell wall deposition causes radial growth of fibre cells in the maturation zone of elongating tall fescue leaf blades. ANNALS OF BOTANY 2002; 89:89-96. [PMID: 12096823 PMCID: PMC4233777 DOI: 10.1093/aob/mcf010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A gradient of development consisting of successive zones of cell division, cell elongation and cell maturation occurs along the longitudinal axis of elongating leaf blades of tall fescue (Festuca arundinacea Schreb.), a C3 grass. An increase in specific leaf weight (SLW; dry weight per unit leaf area) in the maturation region has been hypothesized to result from deposition of secondary cell walls in structural tissues. Our objective was to measure the transverse cell wall area (CWA) associated with the increase in SLW, which occurs following the cessation of leaf blade elongation at about 25 mm distal to the ligule. Digital image analysis of transverse sections at 5, 15, 45, 75 and 105 mm distal to the ligule was used to determine cell number, cell area and protoplast area of structural tissues, namely fibre bundles, mestome sheaths and xylem vessel elements, along the developmental gradient. Cell diameter, protoplast diameter and area, and cell wall thickness and area of fibre bundle cells were calculated from these data. CWA of structural tissues increased in sections up to 75 mm distal to the ligule, confirming the role of cell wall deposition in the increase in SLW (r2 = 0.924; P < or = 0.01). However, protoplast diameter of fibre cells did not decrease significantly as CWA increased, although mean thickness of fibre cell walls increased by 95 % between 15 and 105 mm distal to the ligule. Therefore, secondary cell wall deposition in fibre bundles of tall fescue leaf blades resulted in continued radial expansion of fibre cells rather than in a decrease in protoplast diameter.
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Price LE, Bacon MA, Young PC, Davies WJ. High-resolution analysis of tomato leaf elongation: the application of novel time-series analysis techniques. JOURNAL OF EXPERIMENTAL BOTANY 2001; 52:1925-1932. [PMID: 11520881 DOI: 10.1093/jexbot/52.362.1925] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
This paper demonstrates the use of a novel suite of data-based, recursive modelling techniques for the investigation of biological and other time-series data, including high resolution leaf elongation. The Data-Based Mechanistic (DBM) modelling methodology rejects the common practice of empirical curve fitting for a more objective approach where the model structure is not assumed a priori, but instead is identified directly from the data series in a stochastic form. Further, this novel approach takes advantage of the latest techniques in optimal recursive estimation of non-stationary and non-linear time-series. Here, the utility and ease of use of these techniques is demonstrated in the examination of two time-series of leaf elongation in an expanding leaf of tomato (Lycopersicon esculentum L. cv. Ailsa Craig) growing in a root pressure vessel (RPV). Using this analysis, the component signals of the elongation series are extracted and considered in relation to physiological processes. It is hoped that this paper will encourage the wider use of these new techniques, as well as the associated Data-Based Mechanistic (DBM) modelling strategy, in analytical plant physiology.
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Affiliation(s)
- L E Price
- Institute of Environmental and Natural Sciences (IENS), Lancaster University, Bailrigg, Lancaster LA1 4YQ, UK
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Tardieu F, Reymond M, Hamard P, Granier C, Muller B. Spatial distributions of expansion rate, cell division rate and cell size in maize leaves: a synthesis of the effects of soil water status, evaporative demand and temperature. JOURNAL OF EXPERIMENTAL BOTANY 2000; 51:1505-14. [PMID: 11006302 DOI: 10.1093/jexbot/51.350.1505] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The spatial distributions of leaf expansion rate, cell division rate and cell size was examined under contrasting soil water conditions, evaporative demands and temperatures in a series of experiments carried out in either constant or naturally fluctuating conditions. They were examined in the epidermis and all leaf tissues. (1) Meristem temperature affected relative elongation rate by a constant ratio at all positions in the leaf. If expressed per unit thermal time, the distribution of relative expansion rate was independent of temperature and was similar in all experiments with low evaporative demand and no water deficit. This provides a reference distribution, characteristic of the studied genotype, to which any distribution in stressed plants can be compared. (2) Evaporative demand and soil water deficit affected independently the distribution of relative elongation rate and had near-additive effects. For a given stress, a nearly constant difference was observed, at all positions of the leaf, between the relative elongation rates of stressed plants and those of control plants. This caused a reduction in the length of the zone with tissue elongation. (3) Methods for calculating cell division rate in the epidermis and in all leaf tissues are proposed and discussed. In control plants, the zone with cell division was 30 mm and 60 mm long in the epidermis and in whole tissues, respectively. Both this length and relative division rate were reduced by soil water deficit. The size of epidermal and of mesophyll cells was nearly unaffected in the leaf zone with both cell division and tissue expansion, suggesting that water deficit affects tissue expansion rate and cell division rate to the same extent. Conversely, cell size of epidermis and mesophyll were reduced by water deficit in mature parts of the leaf.
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Affiliation(s)
- F Tardieu
- INRA-ENSAM. Laboratoire d'Ecophysiologie des Plantes sous Stress Environnementaux, Montpellier, France.
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Schnyder, de Visser R. Fluxes of reserve-derived and currently assimilated carbon and nitrogen in perennial ryegrass recovering from defoliation. The regrowing tiller and its component functionally distinct zones. PLANT PHYSIOLOGY 1999; 119:1423-36. [PMID: 10198102 PMCID: PMC32028 DOI: 10.1104/pp.119.4.1423] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/1998] [Accepted: 01/07/1999] [Indexed: 05/20/2023]
Abstract
The quantitative significance of reserves and current assimilates in regrowing tillers of severely defoliated plants of perennial ryegrass (Lolium perenne L.) was assessed by a new approach, comprising 13C/12C and 15N/14N steady-state labeling and separation of sink and source zones. The functionally distinct zones showed large differences in the kinetics of currently assimilated C and N. These are interpreted in terms of "substrate" and "tissue" flux among zones and C and N turnover within zones. Tillers refoliated rapidly, although C and N supply was initially decreased. Rapid refoliation was associated with (a) transient depletion of water-soluble carbohydrates and dilution of structural biomass in the immature zone of expanding leaves, (b) rapid transition to current assimilation-derived growth, and (c) rapid reestablishment of a balanced C:N ratio in growth substrate. This balance (C:N, approximately 8.9 [w/w] in new biomass) indicated coregulation of growth by C and N supply and resulted from complementary fluxes of reserve- and current assimilation-derived C and N. Reserves were the dominant N source until approximately 3 d after defoliation. Amino-C constituted approximately 60% of the net influx of reserve C during the first 2 d. Carbohydrate reserves were an insignificant source of C for tiller growth after d 1. We discuss the physiological mechanisms contributing to defoliation tolerance.
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Affiliation(s)
- Schnyder
- Chair of Grassland Science, Technische Universitat Munchen, D-85350 Freising-Weihenstephan, Germany (H.S.)
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Thompson P, Bowsher CG, Tobin AK. Heterogeneity of mitochondrial protein biogenesis during primary leaf development in barley. PLANT PHYSIOLOGY 1998; 118:1089-99. [PMID: 9808754 PMCID: PMC34782 DOI: 10.1104/pp.118.3.1089] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/1998] [Accepted: 07/21/1998] [Indexed: 05/18/2023]
Abstract
The natural developmental gradient of light-grown primary leaves of barley (Hordeum vulgare L.) was used to analyze the biogenesis of mitochondrial proteins in relation to the age and physiological changes within the leaf. The data indicate that the protein composition of mitochondria changes markedly during leaf development. Three distinct patterns of protein development were noted: group A proteins, consisting of the E1 beta-subunit of the pyruvate dehydrogenase complex, ORF156, ORF577, alternative oxidase, RPS12, cytochrome oxidase subunits II and III, malic enzyme, and the alpha- and beta-subunits of F1-ATPase; group B proteins, consisting of the E1 alpha-subunit of the pyruvate dehydrogenase complex, isocitrate dehydrogenase, HSP70A, cpn60C, and cpn60B; and group C proteins, consisting of the four subunits of the glycine decarboxylase complex (P, H, T, and L proteins), fumarase, and formate dehydrogenase. All of the proteins increased in concentration from the basal meristem to the end of the elongation zone (20.0 mm from the leaf base), whereupon group A proteins decreased, group B proteins increased to a maximum at 50 mm from the leaf base, and group C proteins increased to a maximum at the leaf tip. This study provides evidence of a marked heterogeneity of mitochondrial protein composition, reflecting a changing function as leaf cells develop photosynthetic and photorespiratory capacity.
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Affiliation(s)
- P Thompson
- Plant Science Laboratory, School of Environmental and Evolutionary Biology, Sir Harold Mitchell Building, University of St. Andrews, St. Andrews, Fife KY16 9TH, Scotland (P.T., A.K.T.)
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Peters WS, Bernstein N. The Determination of Relative Elemental Growth Rate Profiles from Segmental Growth Rates (A Methodological Evaluation). PLANT PHYSIOLOGY 1997; 113:1395-1404. [PMID: 12223680 PMCID: PMC158263 DOI: 10.1104/pp.113.4.1395] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Relative elemental growth rate (REGR) profiles describe spatial patterns of growth intensity; they are indispensable for causal growth analyses. Published methods of REGR profile determination from marking experiments fall in two classes: the profile is either described by a series of segmental growth rates, or calculated as the slope of a function describing the displacement velocities of points along the organ. The latter technique is usually considered superior for theoretical reasons, but to our knowledge, no comparative methodological study of the two approaches is currently available. We formulated a model REGR profile that resembles those reported from primary roots. We established the displacement velocity profile and derived growth trajectories, which enabled us to perform hypothetical marking experiments on the model with varying spacing of marks and durations of measurement. REGR profiles were determined from these data by alternative methods, and results were compared to the original profile. We find that with our model plotting of segmental relative growth rates versus segment position provides exact REGR profile estimations, if the initial segment length is less than 10% of the length of the whole growing zone, and if less than 20% of the growing zone is displaced past its boundary during the measurement. Based on our analysis, we discuss systematic errors that occur in marking experiments.
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Affiliation(s)
- W. S. Peters
- Institute of Soils and Water, The Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel
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Elmi AA, West CP. Endophyte infection effects on stomatal conductance, osmotic adjustment and drought recovery of tall fescue. THE NEW PHYTOLOGIST 1995; 131:61-67. [PMID: 33863166 DOI: 10.1111/j.1469-8137.1995.tb03055.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Presence of the endophytic; fungus Acremonium coenophialum Morgan-Jones and Gams in tall fescue (Festuca artuidinacea- Sehreb.) enhances host persistence in drought-prone environments. However, the physiological mechanism is not well understood. We investigated the influence of endophyte infection and water deficit on osmotic adjustment, stomatal conductance, tiller survival and leaf elongation rate of genotype GA87-122 and cv. Kentucky-31 (KY31) of tall fescue. Plants were grown in a greenhouse in pots containing fine-silty topsoil (experiment 1) or sand (experiment 2). In expt 1, endophyte-infected (EI) and endophyte-free (EF) isolines of GA87-122 were exposed to two drought preconditioning cycles, after which all pots were re-watered and osmotic adjustment determined. Osmotic adjustment was -0.46 and -0.51 MPa in El leaf blades and tiller bases and -0.29 and -0.13 MPa in EF leaf blades and tiller bases, respectively. In expt 2, EI and EF GA87-122 and KY31 Mere exposed to severe drought after two preconditioning cycles, then re-watered. During the second preconditioning drying cycle of KY31, stomatal conductance tended to be lower in EI than in EF plants, but the difference was significant (P⩽ 0-05) only at two sampling times. Shoot tissues osmotically adjusted 0.17-0.31 MPa more in EI than in EF plants. Tiller survival and leaf elongation rates were higher (P⩽ 0.05) in preconditioned EI than in EF plants. Basal-zone osmotic adjustment was correlated with tiller survival rate in GA87-122 and KY31 (r = 0.87, P⩽ 0.01 for both). Enhanced osmotic adjustment in the meristematic and growing zone might account far improved survival of tillers by facilitating protection of the apical meristem.
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Affiliation(s)
- A A Elmi
- Agricultural Research Station, Virginia State Univ., Petersburg, VA 23806, USA
| | - C P West
- Department of Agronomy, 276 Altheimer Dr., University of Arkansas, Fayetteville, AR 72704, USA
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Abstract
In grasses, fructan reserves are mobilized from vegetative plant parts during seasonal growth, after defoliation during grazing and from stems during seed filling. Well-illuminated leaves show a diurnal pattern of fructan accumulation during the light and mobilization during the dark. In expanding leaves, fructans are accumulated in cells of the elongation zone and when mobilized are considered to contribute assimilate for synthetic processes. Even in leaves which do not contain high fructan concentrations, high rates of fructan turnover occur. The process of fructan mobilization appears to be regulated in relation to ontogenic events, demand for assimilate during growth and in response to environmental stress. Hydrolysis of fructans in bacteria is catalyzed by both endo- and exohydrolases. However, in higher plants only fructan exohydrolases (FEH) (EC 3.2.1.80) have been reported. FEH has been extracted from only a limited number of grass species. The pH optimum of FEH activities varies between pH 45-5-5, the temperature optimum ranges from 25-40 °C and FEH is considered to be entirely localized in vacuoles. Estimates of the Km for FEH assayed using high molecular weight fructan substrates vary widely and should be considered carefully because most substrates are ill-defined. Many studies indicate that crude and partially-purified FEH activity is highest when assayed using a fructan substrate extracted from the species that was the source of the enzyme activity. Inulin extracted from members of the Asteraceae is generally less readily hydrolyzed and levans from bacteria are relatively poor substrates for FEH from grasses. Glycosidic-linkage-specific hydrolysis has been demonstrated for an FEH activity extracted from barley. This FEH activity hydrolyzed β-2,1-glycosidic linkages more rapidly than β-2,6-linkages. Most other studies are less conclusive because ill-defined fructan substrates were used. Two isoforms of FEH are reported in leaves of Lolium spp., but the roles of isoforms and their kinetic characteristics are not known. FEH activity in different tissues may be regulated by metabolic concentrations, sucrose (5-10 mw) being a strong inhibitor in vitro of FEH from some species. Results of experiments with Dactylis glomerata indicate control of expression of FEH activity at the gene level. In stem bases, FEH activity increased after defoliation. The increase was abolished by applications of inhibitors of protein synthesis and was apparently repressed by application of various sugars. Although the rates of fructan hydrolysis measured in vitro are sufficient to explain the in vivo rates of fructan hydrolysis, it is yet to be shown whether fructan hydrolysis in vivo is due to the activity of FEH exclusively, or FEH and invertase-like activities. The overriding conclusion is that the various studies of FEH from grasses present a confusing and incomplete picture of the function, activity and kinetics of this enzyme. This is due in part to the lack of defined, commercially-available substrates. The chromatographic techniques available to most laboratories do not permit purification of sufficient quantities of high molecular weight fructans of specific degree of polymerization, or fructan oligosaccharides with glycosidic linkages which differ from that of the inulin series for enzyme characterization. It is recommended that a few well-defined oligosaccharides be adopted as substrate standards for future research.
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Affiliation(s)
- Richard J Simpson
- School of Agriculture and Forestry, The University of Melbourne, Parkville, 3052, Australia
| | - Graham D Bonnett
- School of Agriculture and Forestry, The University of Melbourne, Parkville, 3052, Australia
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Meiri A, Silk WK, Läuchli A. Growth and Deposition of Inorganic Nutrient Elements in Developing Leaves of Zea mays L. PLANT PHYSIOLOGY 1992; 99:972-8. [PMID: 16669027 PMCID: PMC1080572 DOI: 10.1104/pp.99.3.972] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Spatial distributions of growth and of the concentration of some inorganic nutrient elements were analyzed in developing leaves of maize (Zea mays L.). Growth was analyzed by pinprick experiments with numerical analysis to characterize fields of velocity and relative elemental elongation rate. Inductively coupled plasma and atomic emission spectroscopy were used to measure nutrients extracted from segments of leaf tissue collected by position. Leaves 7 and 8, both elongating 3 millimeters per hour had maximum relative elemental growth rates of 0.06 to 0.08 millimeters per hour with maximum rates 20 to 50 millimeters from the node and cessation of growth by 90 millimeters from the node. Spatial distribution of dry weight density revealed that the rate of biomass deposition was maximum in the most rapidly expanding region and continued beyond the elongation zone. The nutrient elements K, Cl, Ca, Mg, and P showed different distribution patterns of ion density (on a dry weight basis). K and Cl had minimal density in the leaf tips; K density was maximum in the growing region, whereas Cl density was maximum at the region of growth cessation. Ca, Mg, and P had relatively high densities at the base of the elongation zone near the node and also in the tip regions. Near the node, P and Mg densities were higher in the young, growing leaves, whereas Ca density near the node was higher in older leaves that had completed elongation. Deposition rates of all nutrients were greatest in the region of maximum elongation rate.
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Affiliation(s)
- A Meiri
- Department of Land, Air and Water Resources, University of California, Davis, California 95616
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Allard G, Nelson CJ. Photosynthate partitioning in Basal zones of tall fescue leaf blades. PLANT PHYSIOLOGY 1991; 95:663-8. [PMID: 16668036 PMCID: PMC1077588 DOI: 10.1104/pp.95.3.663] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Elongating grass leaves have successive zones of cell division, cell elongation, and cell maturation in the basal portion of the blade and are a strong sink for photosynthate. Our objective was to determine dry matter (DM) deposition and partitioning in basal zones of elongating tall fescue (Festuca arundinacea Schreb.) leaf blades. Vegetative tall fescue plants were grown in continuous light (350 micromoles per square meter per second photosynthetic photon flux density) to obtain a constant spatial distribution of elongation growth with time. Content and net deposition rates of water-soluble carbohydrates (WSC) and DM along elongating leaf blades were determined. These data were compared with accumulation of (14)C in the basal zones following leaf-labeling with (14)CO(2). Net deposition of DM was highest in the active cell elongation zone, due mainly to deposition of WSC. The maturation zone, just distal to the elongation zone, accounted for 22% of total net deposition of DM in elongating leaves. However, the spatial profile of (14)C accumulation suggested that the elongation zone and the maturation zone were sinks of equal strength. WSC-free DM accounted for 55% of the total net DM deposition in elongating leaf blades, but only 10% of incoming (14)C-photosynthate accumulated in the water-insoluble fraction (WIF approximately WSC-free DM) after 2 hours. In the maturation zone, more WSC was used for synthesis of WSC-free DM than was imported as recent photosynthate.
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Affiliation(s)
- G Allard
- Agronomy Department, University of Missouri, Columbia, Missouri 65211
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Schnyder H, Seo S, Rademacher IF, Kühbauch W. Spatial distribution of growth rates and of epidermal cell lengths in the elongation zone during leaf development in Lolium perenne L. PLANTA 1990; 181:423-31. [PMID: 24196821 DOI: 10.1007/bf00195897] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/1989] [Accepted: 01/23/1990] [Indexed: 05/24/2023]
Abstract
Relative elemental growth rates (REGR) and lengths of epidermal cells along the elongation zone of Lolium perenne L. leaves were determined at four developmental stages ranging from shortly after emergence of the leaf tip to shortly before cessation of leaf growth. Plants were grown at constant light and temperature. At all developmental stages the length of epidermal cells in the elongation zone of both the blade and sheath increased from 12 μm at the leaf base to about 550 μm at the distal end of the elongation zone, whereas the length of epidermal cells within the joint region only increased from 12 to 40 μm. Throughout the developmental stages elongation was confined to the basal 20 to 30 mm of the leaf with maximum REGR occurring near the center of the elongation zone. Leaf elongation rate (LER) and the spatial distributions of REGR and epidermal cell lengths were steady to a first approximation between emergence of the leaf tip and transition from blade to sheath growth. Elongation of epidermal cells in the sheath started immediately after the onset of elongation of the most proximal blade epidermal cells. During transition from blade to sheath growth the length of the blade and sheath portion of the elongation zone decreased and increased, respectively, with the total length of the elongation zone and the spatial distribution of REGR staying near constant, with exception of the joint region which elongated little during displacement through the elongation zone. Leaf elongation rate decreased rapidly during the phase when only the sheath was growing. This was associated with decreasing REGR and only a small decrease in the length of the elongation zone. Data on the spatial distributions of growth rates and of epidermal cell lengths during blade elongation were used to derive the temporal pattern of epidermal cell elongation. These data demonstrate that the elongation rate of an epidermal cell increased for days and that cessation of epidermal cell elongation was an abrupt event with cell elongation rate declining from maximum to zero within less than 10 h.
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Affiliation(s)
- H Schnyder
- Lehrstuhl für Allgemeinen Pflanzenbau, Universität Bonn, Katzenburgweg 5, D-5300, Bonn 1, Germany
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Schnyder H, Nelson CJ. Growth rates and assimilate partitioning in the elongation zone of tall fescue leaf blades at high and low irradiance. PLANT PHYSIOLOGY 1989; 90:1201-6. [PMID: 16666873 PMCID: PMC1061865 DOI: 10.1104/pp.90.3.1201] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Tall fescue (Festuca arundinacea Schreb.) leaf blades elongated 33% faster at continuous low than at continuous high irradiance (60 versus 300 micromoles per second per square meter photosynthetic photon flux density) when temperature of the leaf elongation zone was held constant at 21 degrees C. Increased rate of elongation was associated with a near proportional increase in length of the elongation zone (+38%). In contrast, growth in width and thickness was decreased at low irradiance, resulting in only a 12% increase in leaf area production and 5% less total growth-associated water deposition than at high irradiance. At low irradiance dry matter (DM) import into the elongation zone was 28% less, and 55% less DM was used per unit leaf area produced. DM use in synthesis of structural components (i.e. DM less water-soluble carbohydrates) was only 13% less at low irradiance, whereas water-soluble carbohydrates (WSC) deposition was 43% less. The lower rate of WSC deposition at low irradiance was associated with a higher net rate of monosaccharide deposition (+39%), whereas net deposition rates for sucrose (-27%) and fructan (-56%) were less than at high irradiance. Still, at low irradiance, net fructan accumulation accounted for 64% of WSC deposition, i.e. 25% of DM import, demonstrating the high sink strength of the leaf elongation zone.
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Affiliation(s)
- H Schnyder
- Department of Agronomy, University of Missouri, Columbia, Missouri 65211
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Stayton MM, Brosio P, Dunsmuir P. Photosynthetic Genes of Petunia (Mitchell) Are Differentially Expressed during the Diurnal Cycle. PLANT PHYSIOLOGY 1989; 89:776-82. [PMID: 16666620 PMCID: PMC1055921 DOI: 10.1104/pp.89.3.776] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The petunia (Petunia [Mitchell]) chloroplast proteins, the chlorophyll a/b-binding (Cab) proteins, and the small subunit of ribulose bisphosphate carboxylase (RbcS) are encoded by nuclear genes that are expressed in a light-dependent manner. The steady-state concentrations of five cab mRNAs vary with a dramatic circadian rhythm in plants grown under a constant diurnal cycle (10 hours light, 14 hours dark). cab mRNA levels reach their maximum during the light period, but begin to drop prior to the dark period. These RNAs fall to their minimum concentration during the dark period and then begin to increase again in anticipation of the light. Within this general pattern, there are variations in expression among specific classes of cab genes. The light harvesting complex of photosystem II LHCII-type 1 cab mRNAs rise to a well-defined maximum at 2 hours prior to the dark period. All but one of these genes are expressed in anticipation of the light period. The LHCII type 2 cab mRNA and the LHC of photosystem I cab mRNA are expressed at more constant levels throughout the light period. The expression of these genes anticipates the light more than does the expression of the LHCII type 1 genes. The steady state mRNA levels for the petunia rbcS genes show no significant diurnal fluctuation.
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Affiliation(s)
- M M Stayton
- Advanced Genetic Sciences, Inc., 6701 San Pablo Avenue, Oakland, California 94608
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Macadam JW, Volenec JJ, Nelson CJ. Effects of nitrogen on mesophyll cell division and epidermal cell elongation in tall fescue leaf blades. PLANT PHYSIOLOGY 1989; 89:549-56. [PMID: 16666581 PMCID: PMC1055880 DOI: 10.1104/pp.89.2.549] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Leaf elongation rate (LER) in grasses is dependent on epidermal cell supply (number) and on rate and duration of epidermal cell elongation. Nitrogen (N) fertilization increases LER. Longitudinal sections from two genotypes of tall fescue (Festuca arundinacea Schreb.), which differ by 50% in LER, were used to quantify the effects of N on the components of epidermal cell elongation and on mesophyll cell division. Rate and duration of epidermal cell elongation were determined by using a relationship between cell length and displacement velocity derived from the continuity equation. Rate of epidermal cell elongation was exponential. Relative rates of epidermal cell elongation increased by 9% with high N, even though high N increased LER by 89%. Duration of cell elongation was approximately 20 h longer in the high- than in the low-LER genotype regardless of N treatment. The percentage of mesophyll cells in division was greater in the high- than in the low-LER genotype. This increased with high N in both genotypes, indicating that LER increased with cell supply. Division of mesophyll cells adjacent to abaxial epidermal cells continued after epidermal cell division stopped, until epidermal cells had elongated to a mean length of 40 micrometers in the high-LER and a mean length of 50 micrometers in the low-LER genotype. The cell cycle length for mesophyll cells was calculated to be 12 to 13 hours. Nitrogen increased mesophyll cell number more than epidermal cell number: in both genotypes, the final number of mesophyll cells adjacent to each abaxial epidermal cell was 10 with low N and 14 with high N. A spatial model is used to describe three cell development processes relevant to leaf growth. It illustrates the overlap of mesophyll cell division and epidermal cell elongation, and the transition from epidermal cell elongation to secondary cell wall deposition.
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Affiliation(s)
- J W Macadam
- Department of Agronomy, University of Missouri, Columbia, Missouri 65211
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Schnyder H, Nelson CJ, Spollen WG. Diurnal Growth of Tall Fescue Leaf Blades : II. Dry Matter Partitioning and Carbohydrate Metabolism in the Elongation Zone and Adjacent Expanded Tissue. PLANT PHYSIOLOGY 1988; 86:1077-83. [PMID: 16666034 PMCID: PMC1054630 DOI: 10.1104/pp.86.4.1077] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The spatial distributions of net deposition rates of water soluble carbohydrate-free dry matter (WSC-free DM) and WSC were evaluated within and above the elongation zone of tall fescue (Festuca arundinacea Schreb.) leaf blades during light and darkness. Imported DM used for WSC-free DM synthesis during darkness (67% of the total in experiment I and 59% in experiment II) was greater than during light (47% in both experiments), suggesting that the 65% higher leaf elongation rate during darkness was accompanied by higher rates of synthesis of cellular structural components. Deposition rates of WSC in the basal and central part of the elongation zone (0-20 mm from the ligule) were similar during light and darkness, but above 20 millimeters WSC deposition occurred during light and WSC loss occurred during darkness. WSC deposition and loss throughout the elongation zone and the recently expanded tissue were mostly due to net synthesis and degradation of fructan. Fructan was predominantly low molecular weight and contributed about 50% of the total osmotic partial pressure of WSC. In the most actively growing region, where fructan synthesis was most rapid, no diurnal change occurred in molecular weight distribution of fructan. WSC solute concentrations were diluted in the most actively growing tissue during darkness because net monosaccharide and fructan deposition were unaltered and sucrose deposition was decreased, but growth-associated water deposition was increased by 77%. Net rates of fructan synthesis and degradation were not related to tissue sucrose concentration, but appeared to respond to the balance between assimilate import and assimilate use in synthesis of cellular structural components (i.e. WSC-free DM) and deposition of monosaccharides. Fructan synthesized in tissue during most active elongation was degraded when the respective tissue reached the distal limit of the elongation zone where assimilate import in darkness was insufficient to maintain synthetic processes associated with further differentiation of cells.
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Affiliation(s)
- H Schnyder
- Department of Agronomy, University of Missouri, Columbia, Missouri 65211
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