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Sukhova E, Ratnitsyna D, Gromova E, Sukhov V. Development of Two-Dimensional Model of Photosynthesis in Plant Leaves and Analysis of Induction of Spatial Heterogeneity of CO 2 Assimilation Rate under Action of Excess Light and Drought. PLANTS (BASEL, SWITZERLAND) 2022; 11:plants11233285. [PMID: 36501325 PMCID: PMC9739240 DOI: 10.3390/plants11233285] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/07/2022] [Accepted: 11/23/2022] [Indexed: 05/11/2023]
Abstract
Photosynthesis is a key process in plants that can be strongly affected by the actions of environmental stressors. The stressor-induced photosynthetic responses are based on numerous and interacted processes that can restrict their experimental investigation. The development of mathematical models of photosynthetic processes is an important way of investigating these responses. Our work was devoted to the development of a two-dimensional model of photosynthesis in plant leaves that was based on the Farquhar-von Caemmerer-Berry model of CO2 assimilation and descriptions of other processes including the stomatal and transmembrane CO2 fluxes, lateral CO2 and HCO3- fluxes, transmembrane and lateral transport of H+ and K+, interaction of these ions with buffers in the apoplast and cytoplasm, light-dependent regulation of H+-ATPase in the plasma membrane, etc. Verification of the model showed that the simulated light dependences of the CO2 assimilation rate were similar to the experimental ones and dependences of the CO2 assimilation rate of an average leaf CO2 conductance were also similar to the experimental dependences. An analysis of the model showed that a spatial heterogeneity of the CO2 assimilation rate on a leaf surface should be stimulated under an increase in light intensity and a decrease in the stomatal CO2 conductance or quantity of the open stomata; this prediction was supported by the experimental verification. Results of the work can be the basis of the development of new methods of the remote sensing of the influence of abiotic stressors (at least, excess light and drought) on plants.
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A Changing Light Environment Induces Significant Lateral CO 2 Diffusion within Maize Leaves. Int J Mol Sci 2022; 23:ijms232314530. [PMID: 36498855 PMCID: PMC9736261 DOI: 10.3390/ijms232314530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 11/13/2022] [Accepted: 11/16/2022] [Indexed: 11/23/2022] Open
Abstract
A leaf structure with high porosity is beneficial for lateral CO2 diffusion inside the leaves. However, the leaf structure of maize is compact, and it has long been considered that lateral CO2 diffusion is restricted. Moreover, lateral CO2 diffusion is closely related to CO2 pressure differences (ΔCO2). Therefore, we speculated that enlarging the ΔCO2 between the adjacent regions inside maize leaves may result in lateral diffusion when the diffusion resistance is kept constant. Thus, the leaf structure and gas exchange of maize (C4), cotton (C3), and other species were explored. The results showed that maize and sorghum leaves had a lower mesophyll porosity than cotton and cucumber leaves. Similar to cotton, the local photosynthetic induction resulted in an increase in the ΔCO2 between the local illuminated and the adjacent unilluminated regions, which significantly reduced the respiration rate of the adjacent unilluminated region. Further analysis showed that when the adjacent region in the maize leaves was maintained under a steady high light, the photosynthesis induction in the local regions not only gradually reduced the ΔCO2 between them but also progressively increased the steady photosynthetic rate in the adjacent region. Under field conditions, the ΔCO2, respiration, and photosynthetic rate of the adjacent region were also markedly changed by fluctuating light in local regions in the maize leaves. Consequently, we proposed that enlarging the ΔCO2 between the adjacent regions inside the maize leaves results in the lateral CO2 diffusion and supports photosynthesis in adjacent regions to a certain extent under fluctuating light.
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Moreira JDR, Rosa BL, Lira BS, Lima JE, Correia LNF, Otoni WC, Figueira A, Freschi L, Sakamoto T, Peres LEP, Rossi M, Zsögön A. Auxin-driven ecophysiological diversification of leaves in domesticated tomato. PLANT PHYSIOLOGY 2022; 190:113-126. [PMID: 35639975 PMCID: PMC9434155 DOI: 10.1093/plphys/kiac251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 04/22/2022] [Indexed: 05/29/2023]
Abstract
Heterobaric leaves have bundle sheath extensions (BSEs) that compartmentalize the parenchyma, whereas homobaric leaves do not. The presence of BSEs affects leaf hydraulics and photosynthetic rate. The tomato (Solanum lycopersicum) obscuravenosa (obv) mutant lacks BSEs. Here, we identify the obv gene and the causative mutation, a nonsynonymous amino acid change that disrupts a C2H2 zinc finger motif in a putative transcription factor. This mutation exists as a polymorphism in the natural range of wild tomatoes but has increased in frequency in domesticated tomatoes, suggesting that the latter diversified into heterobaric and homobaric leaf types. The obv mutant displays reduced vein density, leaf hydraulic conductance and photosynthetic assimilation rate. We show that these and other pleiotropic effects on plant development, including changes in leaf insertion angle, leaf margin serration, minor vein density, and fruit shape, are controlled by OBV via changes in auxin signaling. Loss of function of the transcriptional regulator AUXIN RESPONSE FACTOR 4 (ARF4) also results in defective BSE development, revealing an additional component of a genetic module controlling aspects of leaf development important for ecological adaptation and subject to breeding selection.
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Affiliation(s)
- Juliene d R Moreira
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900 Viçosa, Minas Gerais, Brazil
| | - Bruno L Rosa
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900 Viçosa, Minas Gerais, Brazil
| | - Bruno S Lira
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, 05508-090 São Paulo, Brazil
| | - Joni E Lima
- Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, Minas Gerais, Brazil
| | - Ludmila N F Correia
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900 Viçosa, Minas Gerais, Brazil
| | - Wagner C Otoni
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900 Viçosa, Minas Gerais, Brazil
| | - Antonio Figueira
- Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, 13400-970 Piracicaba, São Paulo, Brazil
| | - Luciano Freschi
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, 05508-090 São Paulo, Brazil
| | - Tetsu Sakamoto
- Bioinformatics Multidisciplinary Environment, Instituto Metrópole Digital, Universidade Federal Do Rio Grande Do Norte, 59078-400 Natal, Rio Grande do Norte, Brazil
| | - Lázaro E P Peres
- Laboratory of Hormonal Control of Plant Development, Departamento de Ciências Biológicas (LCB), Escola Superior de Agricultura “Luiz de Queiroz,” Universidade de São Paulo, CP 09, 13418-900 Piracicaba, São Paulo, Brazil
| | - Magdalena Rossi
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, 05508-090 São Paulo, Brazil
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Bulychev AA, Cherkashin AA, Shapiguzov SY, Alova AV. Effects of chloroplast-cytoplasm exchange and lateral mass transfer on slow induction of chlorophyll fluorescence in Characeae. PHYSIOLOGIA PLANTARUM 2021; 173:1901-1913. [PMID: 34414581 DOI: 10.1111/ppl.13531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 08/09/2021] [Accepted: 08/17/2021] [Indexed: 06/13/2023]
Abstract
Rapid cytoplasmic streaming in characean algae mediates communications between remote cell regions exposed to uneven irradiance. The metabolites exported from brightly illuminated chloroplasts spread along the internode with the liquid flow and cause transient changes in chlorophyll fluorescence at cell areas that are exposed to dim light or placed shortly in darkness. The largest distance to which the photometabolites can be transported has not yet been determined. Neither is it known if lateral transport has an influence on the induction of chlorophyll fluorescence. In this study, the relations between spatial connectivity of anchored chloroplasts in characean internodes and fluorescence induction curves were examined. Connectivity between remote cell parts was pronounced upon illumination of a cell spot at a distance up to 10 mm from the area of fluorescence measurement, provided the spot was located upstream in the cytoplasmic flow. Spatial interactions between distant cell sites were also manifested in strikingly different slow stages of fluorescence induction caused by narrow- and wide-field illumination. Cytochalasin D, cooling of bath solution, and inactivation of light-dependent envelope transporters were used to disturb cyclosis-mediated spatial interactions. Although fluorescence induction curves induced by narrow- and wide-field illumination differed greatly under control conditions, they became similar after the inhibition of cyclosis with cytochalasin D. The results indicate that cytoplasmic streaming not only drives the lateral translocation of photometabolites but also promotes the export of reducing power from illuminated chloroplasts due to flushing the chloroplast surface and keeping sharp concentration gradients.
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Affiliation(s)
- Alexander A Bulychev
- Department of Biophysics, Faculty of Biology, Moscow State University, Moscow, Russia
| | | | - Stepan Yu Shapiguzov
- Department of Biophysics, Faculty of Biology, Moscow State University, Moscow, Russia
| | - Anna V Alova
- Department of Biophysics, Faculty of Biology, Moscow State University, Moscow, Russia
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5
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Spangenberg JE, Schweizer M, Zufferey V. Carbon and nitrogen stable isotope variations in leaves of two grapevine cultivars (Chasselas and Pinot noir): Implications for ecophysiological studies. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2021; 163:45-54. [PMID: 33812226 DOI: 10.1016/j.plaphy.2021.03.048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 03/22/2021] [Indexed: 06/12/2023]
Abstract
We investigated the within- and between-leaf variability in the carbon and nitrogen isotope composition (δ13C and δ15N) and total nitrogen (TN) content in two grapevine cultivars (Vitis vinifera cv. Chasselas and Pinot noir) field-grown under rain-fed conditions. The within-leaf variability was studied in discs sampled from base-to-tip and left and right regions from the margin to midrib. The intra- and interplant variability was studied by comparing leaves at different positions along the shoot (basal, median, apical). In leaves from both cultivars, a decrease in δ13C from base to tip was observed, which is in line with an upward gradient of stomatal density and chlorophyll concentration. Less important, but still significant differences were observed between the right and left discs. The leaf TN and δ15N values differed between cultivars, showed smaller variations than the δ13C values, and no systematic spatial trends. The intraleaf variations in δ13C, δ15N, and TN suggest that stomatal behavior, CO2 fixation, chlorophyll concentrations, and the chemical composition of leaf components were heterogeneous in the leaves. At the canopy scale, the apical leaves had less 13C and more 15N and TN than the basal leaves, indicating differences in their photosynthetic capacity and remobilizations from old, senescing leaves to younger leaves. Overall, this study demonstrates patchiness in the δ13C and δ15N values of grapevine leaves and species-specificity of the nitrogen assimilation and 15N fractionation. These findings suggest that care must be taken not to overinterpret foliar δ13C and δ15N values in studies based on fragmented material as markers of physiological and biochemical responses to environmental factors.
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Affiliation(s)
- Jorge E Spangenberg
- Institute of Earth Surface Dynamics (IDYST), University of Lausanne, CH-1015, Lausanne, Switzerland.
| | - Marc Schweizer
- Institute of Earth Surface Dynamics (IDYST), University of Lausanne, CH-1015, Lausanne, Switzerland
| | - Vivian Zufferey
- Institute of Plant Production Sciences (IPV), Agroscope, CH-1009, Pully, Switzerland
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6
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Marler TE. Artifleck: The Study of Artifactual Responses to Light Flecks with Inappropriate Leaves. PLANTS 2020; 9:plants9070905. [PMID: 32708982 PMCID: PMC7412511 DOI: 10.3390/plants9070905] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 06/30/2020] [Accepted: 07/08/2020] [Indexed: 12/25/2022]
Abstract
Methods in sunfleck research commonly employ the use of experimental leaves which were constructed in homogeneous light. These experimental organs may behave unnaturally when they are challenged with fluctuating light. Photosynthetic responses to heterogeneous light and leaf macronutrient relations were determined for Cycas micronesica, Glycine max, and Zea mays leaves that were grown in homogeneous shade, heterogeneous shade, or full sun. The speed of priming where one light fleck increased the photosynthesis during a subsequent light fleck was greatest for the leaves grown in heterogeneous shade. The rate of induction and the ultimate steady-state photosynthesis were greater for the leaves that were grown in heterogeneous shade versus the leaves grown in homogeneous shade. The leaf mass per area, macronutrient concentration, and macronutrient stoichiometry were also influenced by the shade treatments. The amplitude and direction in which the three developmental light treatments influenced the response variables were not universal among the three model species. The results indicate that the historical practice of using experimental leaves which were constructed under homogeneous light to study leaf responses to fluctuating light may produce artifacts that generate dubious interpretations.
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Affiliation(s)
- Thomas E Marler
- Western Pacific Tropical Research Center, College of Natural and Applied Sciences, University of Guam, Mangilao, GU 96923, USA
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Nunes-Nesi A, Nascimento VDL, de Oliveira Silva FM, Zsögön A, Araújo WL, Sulpice R. Natural genetic variation for morphological and molecular determinants of plant growth and yield. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:2989-3001. [PMID: 27012286 DOI: 10.1093/jxb/erw124] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The rates of increase in yield of the main commercial crops have been steadily falling in many areas worldwide. This generates concerns because there is a growing demand for plant biomass due to the increasing population. Plant yield should thus be improved in the context of climate change and decreasing natural resources. It is a major challenge which could be tackled by improving and/or altering light-use efficiency, CO2 uptake and fixation, primary metabolism, plant architecture and leaf morphology, and developmental plant processes. In this review, we discuss some of the traits which could lead to yield increase, with a focus on how natural genetic variation could be harnessed. Moreover, we provide insights for advancing our understanding of the molecular aspects governing plant growth and yield, and propose future avenues for improvement of crop yield. We also suggest that knowledge accumulated over the last decade in the field of molecular physiology should be integrated into new ideotypes.
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Affiliation(s)
- Adriano Nunes-Nesi
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Vitor de Laia Nascimento
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Franklin Magnum de Oliveira Silva
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Agustin Zsögön
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Wagner L Araújo
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Ronan Sulpice
- National University of Ireland, Galway, Plant Systems Biology Lab, Plant and AgriBiosciences Research Centre, School of Natural Sciences, Galway, Ireland
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Kamakura M, Kosugi Y, Takanashi S, Uemura A, Utsugi H, Kassim AR. Occurrence of stomatal patchiness and its spatial scale in leaves from various sizes of trees distributed in a South-east Asian tropical rainforest in Peninsular Malaysia. TREE PHYSIOLOGY 2015; 35:61-70. [PMID: 25595752 DOI: 10.1093/treephys/tpu109] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
In this study, we demonstrated the occurrence of stomatal patchiness and its spatial scale in leaves from various sizes of trees grown in a lowland dipterocarp forest in Peninsular Malaysia. To evaluate the patterns of stomatal behavior, we used three techniques simultaneously to analyze heterobaric or homobaric leaves from five tree species ranging from 0.6 to 31 m in height: (i) diurnal changes in chlorophyll fluorescence imaging, (ii) observation and simulation of leaf gas-exchange rates and (iii) a pressure-infiltration method. Measurements were performed in situ with 1000 or 500 μmol m(-2) s(-1) photosynthetic photon flux density. Diurnal patterns in the spatial distribution of photosynthetic electron transport rate (J) mapped from chlorophyll fluorescence images, a comparison of observed and simulated leaf gas-exchange rates, and the spatial distribution of stomatal apertures obtained from the acid-fuchsin-infiltrated area showed that patchy stomatal closure coupled with severe midday depression of photosynthesis occurred in Neobalanocarpus heimii (King) Ashton, a higher canopy tree with heterobaric leaves due to the higher leaf temperature and vapor pressure deficit. However, subcanopy or understory trees showed uniform stomatal behavior throughout the day, although they also have heterobaric leaves. These results suggest that the occurrence of stomatal patchiness is determined by tree size and/or environmental conditions. The analysis of spatial scale by chlorophyll fluorescence imaging showed that several adjacent anatomical patches (lamina areas bounded by bundle-sheath extensions within the lamina) may co-operate for the distributed patterns of J and stomatal apertures.
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Affiliation(s)
- Mai Kamakura
- Laboratory of Forest Hydrology, Division of Environmental Science and Technology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Yoshiko Kosugi
- Laboratory of Forest Hydrology, Division of Environmental Science and Technology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Satoru Takanashi
- Forestry and Forest Products Research Institute, Tsukuba, Ibaraki 305-8687, Japan
| | - Akira Uemura
- Hokkaido Research Center, Forestry and Forest Products Research Institute, Sapporo 062-8516, Japan
| | - Hajime Utsugi
- Forestry and Forest Products Research Institute, Tsukuba, Ibaraki 305-8687, Japan
| | - Abd Rahman Kassim
- Forest Research Institute Malaysia, Kepong, Selangor 52109, Malaysia
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Zsögön A, Negrini ACA, Peres LEP, Nguyen HT, Ball MC. A mutation that eliminates bundle sheath extensions reduces leaf hydraulic conductance, stomatal conductance and assimilation rates in tomato (Solanum lycopersicum). THE NEW PHYTOLOGIST 2015; 205:618-26. [PMID: 25267094 DOI: 10.1111/nph.13084] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2014] [Accepted: 08/22/2014] [Indexed: 05/05/2023]
Abstract
Bundle sheath extensions (BSEs) are key features of leaf structure whose distribution differs among species and ecosystems. The genetic control of BSE development is unknown, so BSE physiological function has not yet been studied through mutant analysis. We screened a population of ethyl methanesulfonate (EMS)-induced mutants in the genetic background of the tomato (Solanum lycopersicum) model Micro-Tom and found a mutant lacking BSEs. The leaf phenotype of the mutant strongly resembled the tomato mutant obscuravenosa (obv). We confirmed that obv lacks BSEs and that it is not allelic to our induced mutant, which we named obv-2. Leaves lacking BSEs had lower leaf hydraulic conductance and operated with lower stomatal conductance and correspondingly lower assimilation rates than wild-type leaves. This lower level of function occurred despite similarities in vein density, midvein vessel diameter and number, stomatal density, and leaf area between wild-type and mutant leaves, the implication being that the lack of BSEs hindered water dispersal within mutant leaves. Our results comparing near-isogenic lines within a single species confirm the hypothesised role of BSEs in leaf hydraulic function. They further pave the way for a genetic model-based analysis of a common leaf structure with deep ecological consequences.
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Affiliation(s)
- Agustin Zsögön
- Departamento de Ciências Biológicas, Escola Superior de Agricultura 'Luiz de Queiroz', Universidade de São Paulo, CP 09, 13418-900, Piracicaba, SP, Brazil
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10
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Tholen D, Boom C, Zhu XG. Opinion: prospects for improving photosynthesis by altering leaf anatomy. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2012; 197:92-101. [PMID: 23116676 DOI: 10.1016/j.plantsci.2012.09.005] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Revised: 09/11/2012] [Accepted: 09/13/2012] [Indexed: 05/05/2023]
Abstract
Engineering higher photosynthetic efficiency for greater crop yields has gained significant attention among plant biologists and breeders. To achieve this goal, manipulation of metabolic targets and canopy architectural features has been heavily emphasized. Given the substantial variations in leaf anatomical features among and within plant species, there is large potential to engineer leaf anatomy for improved photosynthetic efficiency. Here we review how different leaf anatomical features influence internal light distribution, delivery of CO(2) to Rubisco and water relations, and accordingly recommend features to engineer for increased leaf photosynthesis under different environments. More research is needed on (a) elucidating the genetic mechanisms controlling leaf anatomy, and (b) the development of a three dimensional biochemical and biophysical model of leaf photosynthesis, which can help pinpoint anatomical features required to gain a higher photosynthesis.
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Affiliation(s)
- Danny Tholen
- CAS Key Laboratory of Computational Biology, CAS-MPG (Chinese Academy of Sciences-German Max Planck Society) Partner Institute for Computational Biology, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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Asensio AC, Gil-Monreal M, Pires L, Gogorcena Y, Aparicio-Tejo PM, Moran JF. Two Fe-superoxide dismutase families respond differently to stress and senescence in legumes. JOURNAL OF PLANT PHYSIOLOGY 2012; 169:1253-60. [PMID: 22840995 DOI: 10.1016/j.jplph.2012.04.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 04/20/2012] [Accepted: 04/20/2012] [Indexed: 06/01/2023]
Abstract
Three main families of SODs in plants may be distinguished according to the metal in the active center: CuZnSODs, MnSOD, and FeSOD. CuZnSODs have two sub-families localized either in plant cell cytosol or in plastids, the MnSOD family is essentially restricted to mitochondria, and the FeSOD enzyme family has been typically localized into the plastid. Here, we describe, based on a phylogenetic tree and experimental data, the existence of two FeSOD sub-families: a plastidial localized sub-family that is universal to plants, and a cytosolic localized FeSOD sub-family observed in determinate-forming nodule legumes. Anti-cytosolic FeSOD (cyt_FeSOD) antibodies were employed, together with a novel antibody raised against plastidial FeSOD (p_FeSOD). Stress conditions, such as nitrate excess or drought, markedly increased cyt_FeSOD contents in soybean tissues. Also, cyt_FeSOD content and activity increased with age in both soybean and cowpea plants, while the cyt_CuZnSOD isozyme was predominant during early stages. p_FeSOD in leaves decreased with most of the stresses applied, but this isozyme markedly increased with abscisic acid in roots. The great differences observed for p_FeSOD and cyt_FeSOD contents in response to stress and aging in plant tissues reveal distinct functionality and confirm the existence of two immunologically differentiated FeSOD sub-families. The in-gel FeSOD activity patterns showed a good correlation to cyt_FeSOD contents but not to those of p_FeSOD. This indicates that cyt_FeSOD is the main active FeSOD in soybean and cowpea tissues. The diversity of functions associated with the complexity of FeSOD isoenzymes depending of the location is discussed.
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Affiliation(s)
- Aaron C Asensio
- Institute of Agro-Biotechnology, IdAB-CSIC-Public University of Navarre-Government of Navarre, Campus de Arrosadía s/n, E-31006 Pamplona, Navarra, Spain
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12
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Guàrdia M, Fernàndez J, Elena G, Fleck I. Stomatal patchiness in the Mediterranean holm oak (Quercus ilex L.) under water stress in the nursery and in the forest. TREE PHYSIOLOGY 2012; 32:829-838. [PMID: 22539636 DOI: 10.1093/treephys/tps035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The evergreen holm oak Quercus ilex L. is the most representative tree in Mediterranean forests. Accurate estimation of the limiting factors of photosynthesis for Q. ilex and the prediction of ecosystem water-use efficiency by mechanistic models can be achieved only by establishing whether this species shows heterogenic stomatal aperture, and, if so, the circumstances in which this occurs. Here, we collected gas-exchange and chlorophyll fluorescence data in Q. ilex leaves from a nursery to measure the effects of stomatal oscillations on PSII quantum yield (Φ(PSII)) under water stress. Stomatal conductance (g(s)) was used as an integrative indicator of the degree of water stress. Images of chlorophyll fluorescence showed heterogeneous Φ(PSII) when g(s) was <50 mmol H(2)O m(-2) s(-1), representative of severe drought and corresponding to a container capacity <45%. Stomatal patchiness was related to a coefficient of variation (CV) of Φ(PSII) values >2.5%. A parallel study in the forest confirmed heterogeneous Φ(PSII) values in leaves in response to declining water availability. Three kinds of Q. ilex individuals were distinguished: those resprouting after a clear-cut (resprouts, R); intact individuals growing in the same clear-cut area as resprouts (controls, C); and intact individuals in a nearby, undisturbed area (forest controls, CF). Patchiness increased in C and CF in response to increasing drought from early May to late July, whereas in R, Φ(PSII) values were maintained as a result of their improved water relations since the pre-existing roots were associated with a smaller aerial biomass. Patchiness was related to a % CV of Φ(PSII) values >4 and associated in the summer with mean g(s) values of 30 mmol H(2)O m(-2) s(-1). Under milder drought in spring, Φ(PSII) patchiness was less strictly related to g(s) variations, pointing to biochemical limitants of photosynthesis. The occurrence of heterogenic photosynthesis caused by patchy stomatal closure in Q. ilex during severe drought should be taken into account in ecosystem modelling in which harsher water stress conditions associated with climate change are predicted.
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Affiliation(s)
- Mercè Guàrdia
- Departament de Biologia Vegetal, Unitat Fisiologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Diagonal 643, E-08028 Barcelona, Spain
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