1
|
Heise CM, Hagemann M, Schubert H. Photosynthetic response of Chara braunii towards different bicarbonate concentrations. PHYSIOLOGIA PLANTARUM 2024; 176:e14234. [PMID: 38439180 DOI: 10.1111/ppl.14234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 02/11/2024] [Accepted: 02/15/2024] [Indexed: 03/06/2024]
Abstract
A variety of inorganic carbon acquisition modes have been proposed in Characean algae, however, a broadly applicable inorganic carbon uptake mechanism is unknown for the genus Chara. In the present study, we analyzed if C. braunii can efficiently use HCO3 - as a carbon source for photosynthesis. For this purpose, C. braunii was exposed to different concentrations of NaHCO3 - at different time scales. The photosynthetic electron transport through photosystem I (PSI) and II (PSII), the maximum electron transport rate (ETRmax ), the efficiency of the electron transport rate (α, the initial slope of the ETR), and the light saturation point of photosynthesis (Ek ) were evaluated. Additionally, pigment contents (chlorophyll a, chlorophyll b, and carotenoids) were determined. Bicarbonate addition positively affected ETRmax , after direct HCO3 - application, of both PSII and PSI, but this effect seems to decrease after 1 h and 24 h. Similar trends were seen for Ek , but no significant effect was observed for α. Pigment contents showed no significant changes in relation to different HCO3 - concentrations. To evaluate if cyclic electron flow around PSI was involved in active HCO3 - uptake, the ratio of PSI ETRmax /PSII ETRmax was calculated but did not show a distinctive trend. These results suggest that C. braunii can utilize NaHCO3 - in short-term periods as a carbon source but could rely on other carbon acquisition mechanisms over prolonged time periods. These observations suggest that the minor role of HCO3 - as a carbon source for photosynthesis in this alga might differentiate C. braunii from other examined Chara spp.
Collapse
Affiliation(s)
- Carolin Magdalene Heise
- Institute of Biosciences, Department of Aquatic Ecology, University of Rostock, Rostock, Germany
- Institute of Biosciences, Department of Plant Physiology, University of Rostock, Rostock, Germany
| | - Martin Hagemann
- Institute of Biosciences, Department of Plant Physiology, University of Rostock, Rostock, Germany
| | - Hendrik Schubert
- Institute of Biosciences, Department of Aquatic Ecology, University of Rostock, Rostock, Germany
| |
Collapse
|
2
|
Capó-Bauçà S, Iñiguez C, Aguiló-Nicolau P, Galmés J. Correlative adaptation between Rubisco and CO 2-concentrating mechanisms in seagrasses. NATURE PLANTS 2022; 8:706-716. [PMID: 35729266 DOI: 10.1038/s41477-022-01171-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 05/13/2022] [Indexed: 05/19/2023]
Abstract
Submerged angiosperms sustain some of the most productive and diverse ecosystems worldwide. However, their carbon acquisition and assimilation mechanisms remain poorly explored, missing an important step in the evolution of photosynthesis during the colonization of aquatic environments by angiosperms. Here we reveal a convergent kinetic adaptation of Rubisco in phylogenetically distant seagrass species that share catalytic efficiencies and CO2 and O2 affinities up to three times lower than those observed in phylogenetically closer angiosperms from terrestrial, freshwater and brackish-water habitats. This Rubisco kinetic convergence was found to correlate with the effectiveness of seagrass CO2-concentrating mechanisms (CCMs), which probably evolved in response to the constant CO2 limitation in marine environments. The observed Rubisco kinetic adaptation in seagrasses more closely resembles that seen in eukaryotic algae operating CCMs rather than that reported in terrestrial C4 plants. Our results thus demonstrate a general pattern of co-evolution between Rubisco function and biophysical CCM effectiveness that traverses distantly related aquatic lineages.
Collapse
Affiliation(s)
- Sebastià Capó-Bauçà
- Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears-INAGEA, Palma, Spain
| | - Concepción Iñiguez
- Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears-INAGEA, Palma, Spain.
| | - Pere Aguiló-Nicolau
- Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears-INAGEA, Palma, Spain
| | - Jeroni Galmés
- Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears-INAGEA, Palma, Spain
| |
Collapse
|
3
|
Pan Y, Cieraad E, Clarkson BR, Colmer TD, Pedersen O, Visser EJW, Voesenek LACJ, Bodegom PM. Drivers of plant traits that allow survival in wetlands. Funct Ecol 2020. [DOI: 10.1111/1365-2435.13541] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yingji Pan
- Institute of Environmental Sciences (CML) Leiden University Leiden The Netherlands
| | - Ellen Cieraad
- Institute of Environmental Sciences (CML) Leiden University Leiden The Netherlands
| | | | - Timothy D. Colmer
- School of Agriculture and Environment The University of Western Australia Perth WA Australia
| | - Ole Pedersen
- School of Agriculture and Environment The University of Western Australia Perth WA Australia
- Freshwater Biological Laboratory University of Copenhagen Copenhagen Denmark
| | - Eric J. W. Visser
- Experimental Plant Ecology Institute for Water and Wetland Research Radboud University Nijmegen The Netherlands
| | | | - Peter M. Bodegom
- Institute of Environmental Sciences (CML) Leiden University Leiden The Netherlands
| |
Collapse
|
4
|
Lenzewski N, Mueller P, Meier RJ, Liebsch G, Jensen K, Koop-Jakobsen K. Dynamics of oxygen and carbon dioxide in rhizospheres of Lobelia dortmanna - a planar optode study of belowground gas exchange between plants and sediment. THE NEW PHYTOLOGIST 2018; 218:131-141. [PMID: 29314005 DOI: 10.1111/nph.14973] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 11/21/2017] [Indexed: 05/24/2023]
Abstract
Root-mediated CO2 uptake, O2 release and their effects on O2 and CO2 dynamics in the rhizosphere of Lobelia dortmanna were investigated. Novel planar optode technology, imaging CO2 and O2 distribution around single roots, provided insights into the spatiotemporal patterns of gas exchange between roots, sediment and microbial community. In light, O2 release and CO2 uptake were pronounced, resulting in a distinct oxygenated zone (radius: c. 3 mm) and a CO2 -depleted zone (radius: c. 2 mm) around roots. Simultaneously, however, microbial CO2 production was stimulated within a larger zone around the roots (radius: c. 10 mm). This gave rise to a distinct pattern with a CO2 minimum at the root surface and a CO2 maximum c. 2 mm away from the root. In darkness, CO2 uptake ceased, and the CO2 -depleted zone disappeared within 2 h. By contrast, the oxygenated root zone remained even after 8 h, but diminished markedly over time. A tight coupling between photosynthetic processes and the spatiotemporal dynamics of O2 and CO2 in the rhizosphere of Lobelia was demonstrated, and we suggest that O2 -induced stimulation of the microbial community in the sediment increases the supply of inorganic carbon for photosynthesis by building up a CO2 reservoir in the rhizosphere.
Collapse
Affiliation(s)
- Nikola Lenzewski
- Applied Plant Ecology, Biocenter Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, 22609, Hamburg, Germany
| | - Peter Mueller
- Applied Plant Ecology, Biocenter Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, 22609, Hamburg, Germany
| | | | - Gregor Liebsch
- PreSens, Precision Sensing GmbH, Am BioPark 11, 93053, Regensburg, Germany
| | - Kai Jensen
- Applied Plant Ecology, Biocenter Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, 22609, Hamburg, Germany
| | - Ketil Koop-Jakobsen
- MARUM - Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse 8, 28359, Bremen, Germany
| |
Collapse
|
5
|
Reitsema RE, Meire P, Schoelynck J. The Future of Freshwater Macrophytes in a Changing World: Dissolved Organic Carbon Quantity and Quality and Its Interactions With Macrophytes. FRONTIERS IN PLANT SCIENCE 2018; 9:629. [PMID: 29868084 PMCID: PMC5960680 DOI: 10.3389/fpls.2018.00629] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 04/20/2018] [Indexed: 05/22/2023]
Abstract
Freshwater ecosystems are confronted with the effects of climate change. One of the major changes is an increased concentration of aquatic carbon. Macrophytes are important in the aquatic carbon cycle and play as primary producers a crucial role in carbon storage in aquatic systems. However, macrophytes are affected by increasing carbon concentrations. The focus of this review lies on dissolved organic carbon (DOC), one of the most abundant forms of carbon in aquatic ecosystems which has many effects on macrophytes. DOC concentrations are rising; the exact cause of this increase is not known, although it is hypothesized that climate change is one of the drivers. The quality of DOC is also changing; for example, in urban areas DOC composition is different from the composition in natural watersheds, resulting in DOC that is more resistant to photo-degradation. Plants can benefit from DOC as it attenuates UV-B radiation, it binds potentially harmful heavy metals and provides CO2 as it breaks down. Yet plant growth can also be impaired under high DOC concentrations, especially by humic substances (HS). HS turn the water brown and attenuate light, which limits macrophyte photosynthesis at greater depths. This leads to lower macrophyte abundance and lower species diversity. HS form a wide class of chemicals with many different functional groups and they therefore have the ability to interfere with many biochemical processes that occur in freshwater organisms. Few studies have looked into the direct effects of HS on macrophytes, but there is evidence that HS can interfere with photosynthesis by entering macrophyte cells and causing damage. DOC can also affect reactivity of heavy metals, water and sediment chemistry. This indirectly affects macrophytes too, so they are exposed to multiple stressors that may have contradictive effects. Finally, macrophytes can affect DOC quality and quantity as they produce DOC themselves and provide a substrate to heterotrophic bacteria that degrade DOC. Because macrophytes take a key position in the aquatic ecosystem, it is essential to understand to what extent DOC quantity and quality in surface water are changing and how this will affect macrophyte growth and species diversity in the future.
Collapse
|
6
|
Titus JE, Pagano AM. Carbon dioxide and submersed macrophytes in lakes: linking functional ecology to community composition. Ecology 2017; 98:3096-3105. [DOI: 10.1002/ecy.2030] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 08/23/2017] [Accepted: 08/29/2017] [Indexed: 12/22/2022]
Affiliation(s)
- John E. Titus
- Department of Biological Sciences State University of New York at Binghamton Binghamton New York 13902 USA
| | - Angela M. Pagano
- Department of Biological Sciences State University of New York at Binghamton Binghamton New York 13902 USA
| |
Collapse
|
7
|
Pellegrini E, Konnerup D, Winkel A, Casolo V, Pedersen O. Contrasting oxygen dynamics in Limonium narbonense and Sarcocornia fruticosa during partial and complete submergence. FUNCTIONAL PLANT BIOLOGY : FPB 2017; 44:867-876. [PMID: 32480615 DOI: 10.1071/fp16369] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 05/05/2017] [Indexed: 06/11/2023]
Abstract
Terrestrial saltmarsh plants inhabiting flood-prone habitats undergo recurrent and prolonged flooding driven by tidal regimes. In this study, the role of internal plant aeration in contrasting hypoxic/anoxic conditions during submergence was investigated in the two halophytes Limonium narbonense Mill. and Sarcocornia fruticosa (L.) A.J. Scott. Monitoring of tissue O2 dynamics was performed in shoots and roots using microelectrodes under drained conditions, waterlogging, partial and complete submergence, in light or darkness. For both species, submergence in darkness resulted in significant declines in tissue O2 status and when in light, in rapid O2 increases first in shoot tissues and subsequently in roots. During partial submergence, S. fruticosa benefitted from snorkelling and efficiently transported O2 to roots, whereas the O2 concentration in roots of L. narbonense declined by more than 90%. Significantly thinner leaves and articles were recorded under high degree of flooding stress and both species showed considerably high tissue porosity. The presence of aerenchyma seemed to support internal aeration in S. fruticosa whereas O2 diffusion in L. narbonense seemed impeded, despite the higher porosity (up to 50%). Thus, the results obtained for L. narbonense, being well adapted to flooding, suggests that processes other than internal aeration could be involved in better flooding tolerance e.g. fermentative processes, and that traits resulting in flooding tolerance in plants are not yet fully understood.
Collapse
Affiliation(s)
- Elisa Pellegrini
- Plant Biology Unit, Department of Agricultural, Food, Environmental and Animal Science, University of Udine, via delle Scienze 206, 33100 Udine, Italy
| | - Dennis Konnerup
- Freshwater Biological Laboratory, Department of Biology, University of Copenhagen, Universitetsparken 4, 2100 Copenhagen, Denmark
| | - Anders Winkel
- Freshwater Biological Laboratory, Department of Biology, University of Copenhagen, Universitetsparken 4, 2100 Copenhagen, Denmark
| | - Valentino Casolo
- Plant Biology Unit, Department of Agricultural, Food, Environmental and Animal Science, University of Udine, via delle Scienze 206, 33100 Udine, Italy
| | - Ole Pedersen
- Freshwater Biological Laboratory, Department of Biology, University of Copenhagen, Universitetsparken 4, 2100 Copenhagen, Denmark
| |
Collapse
|
8
|
Maberly SC, Gontero B. Ecological imperatives for aquatic CO2-concentrating mechanisms. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:3797-3814. [PMID: 28645178 DOI: 10.1093/jxb/erx201] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In aquatic environments, the concentration of inorganic carbon is spatially and temporally variable and CO2 can be substantially oversaturated or depleted. Depletion of CO2 plus low rates of diffusion cause inorganic carbon to be more limiting in aquatic than terrestrial environments, and the frequency of species with a CO2-concentrating mechanism (CCM), and their contribution to productivity, is correspondingly greater. Aquatic photoautotrophs may have biochemical or biophysical CCMs and exploit CO2 from the sediment or the atmosphere. Though partly constrained by phylogeny, CCM activity is related to environmental conditions. CCMs are absent or down-regulated when their increased energy costs, lower CO2 affinity, or altered mineral requirements outweigh their benefits. Aquatic CCMs are most widespread in environments with low CO2, high HCO3-, high pH, and high light. Freshwater species are generally less effective at inorganic carbon removal than marine species, but have a greater range of ability to remove carbon, matching the environmental variability in carbon availability. The diversity of CCMs in seagrasses and marine phytoplankton, and detailed mechanistic studies on larger aquatic photoautotrophs are understudied. Strengthening the links between ecology and CCMs will increase our understanding of the mechanisms underlying ecological success and will place mechanistic studies in a clearer ecological context.
Collapse
Affiliation(s)
- Stephen C Maberly
- Lake Ecosystems Group, Centre for Ecology & Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP, UK
| | - Brigitte Gontero
- Aix Marseille Univ, CNRS, BIP, UMR 7281, IMM, FR 3479, 31 Chemin J. Aiguier, 13 402 Marseille, Cedex 20, France
| |
Collapse
|
9
|
Raven JA, Colmer TD. Life at the boundary: photosynthesis at the soil-fluid interface. A synthesis focusing on mosses. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:1613-23. [PMID: 26842980 DOI: 10.1093/jxb/erw012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Mosses are among the earliest branching embryophytes and probably originated not later than the early Ordovician when atmospheric CO2 was higher and O2 was lower than today. The C3 biochemistry and physiology of their photosynthesis suggests, by analogy with tracheophytes, that growth of extant bryophytes in high CO2 approximating Ordovician values would increase the growth rate. This occurs for many mosses, including Physcomitrella patens in suspension culture, although recently published transcriptomic data on this species at high CO2 and present-day CO2 show down-regulation of the transcription of several genes related to photosynthesis. It would be useful if transcriptomic (and proteomic) data comparing growth conditions are linked to measurements of growth and physiology on the same, or parallel, cultures. Mosses (like later-originating embryophytes) have been subject to changes in bulk atmospheric CO2 and O2 throughout their existence, with evidence, albeit limited, for positive selection of moss Rubisco. Extant mosses are subject to a large range of CO2 and O2 concentrations in their immediate environments, especially aquatic mosses, and mosses are particularly influenced by CO2 generated by, and O2 consumed by, soil chemoorganotrophy from organic C produced by tracheophytes (if present) and bryophytes.
Collapse
Affiliation(s)
- John A Raven
- Permanent address: Division of Plant Sciences, University of Dundee at the James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK School of Plant Biology, The University of Western Australia, M084, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Timothy D Colmer
- School of Plant Biology, The University of Western Australia, M084, 35 Stirling Highway, Crawley, WA 6009, Australia
| |
Collapse
|
10
|
Comparing photosynthetic characteristics of Isoetes sinensis Palmer under submerged and terrestrial conditions. Sci Rep 2015; 5:17783. [PMID: 26634994 PMCID: PMC4669503 DOI: 10.1038/srep17783] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 11/04/2015] [Indexed: 01/29/2023] Open
Abstract
Crassulacean acid metabolism (CAM) is widespread in terrestrial and aquatic species, plastic in response to environmental changes. Isoetes L. is one of the earliest basal vascular plants and CAM is popular in this genus. Isoetes sinensis Palmer is an amphibious species, alternating frequently between terrestrial and aquatic environments. Given this, we investigated and compared photosynthetic characteristics over a diurnal cycle under submerged condition (SC) and terrestrial condition (TC). The results suggest that I. sinensis possesses a stronger CAM capacity under SC. Compared with under TC, titratable acidity levels and organic acid concentrations were more enriched under SC, whereas soluble sugar or starch and protein levels were lower under SC. Transcript analyses for nine photosynthetic genes revealed that CAM-associated genes possessed high transcripts under SC, but C3-related transcripts were highly expressed under TC. In addition, the enzyme activity measurements demonstrated that PEPC activity over a diurnal cycle was slightly higher under SC, whereas Rubisco activity during the daytime was greater under TC. This comprehensive study probably facilitates general understandings about the CAM photosynthetic characteristics of Isoetes in response to the environmental changes.
Collapse
|
11
|
Forrestel EJ, Ackerly DD, Emery NC. The joint evolution of traits and habitat: ontogenetic shifts in leaf morphology and wetland specialization in Lasthenia. THE NEW PHYTOLOGIST 2015; 208:949-959. [PMID: 26037170 DOI: 10.1111/nph.13478] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 04/24/2015] [Indexed: 06/04/2023]
Abstract
The interplay between functional traits and habitat associations drives species' evolutionary responses to environmental heterogeneity, including processes such as adaptation, ecological speciation, and niche evolution. Seasonal variation is an aspect of the environment that varies across habitats, and could result in adaptive shifts in trait values across the life cycle of a plant. Here, we use phylogenetic comparative methods to evaluate the joint evolution of plant traits and habitat associations in Lasthenia (Asteraceae), a small clade of predominantly annual plants that have differentiated into an ecologically diverse range of habitats, including seasonal ephemeral wetlands known as vernal pools. Our results support the hypothesis that there is a link between the evolution of leaf morphology and the ecohydrological niche in Lasthenia, and, in the formation of aerenchyma (air space), differentiation between vernal pool and terrestrial taxa is fine-tuned to specific stages of plant ontogeny that reflects the evolution of heterophylly. Our findings demonstrate how the relationships between traits and habitat type can vary across the development of an organism, while highlighting a carefully considered comparative approach for examining correlated trait and niche evolution in a recently diversified and ecologically diverse plant clade.
Collapse
Affiliation(s)
- Elisabeth J Forrestel
- Department of Ecology and Evolution, Yale University, New Haven, CT, 06520-8105, USA
| | - David D Ackerly
- Department of Integrative Biology and Jepson Herbarium, University of California, Berkeley, CA, 94720, USA
| | - Nancy C Emery
- Department of Ecology and Evolutionary Biology, University of Colorado, UCB 334, Boulder, CO, 80309, USA
| |
Collapse
|
12
|
Colmer TD, Armstrong W, Greenway H, Ismail AM, Kirk GJD, Atwell BJ. Physiological Mechanisms of Flooding Tolerance in Rice: Transient Complete Submergence and Prolonged Standing Water. PROGRESS IN BOTANY 2014. [DOI: 10.1007/978-3-642-38797-5_9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
|
13
|
Winkel A, Colmer TD, Pedersen O. Leaf gas films of Spartina anglica enhance rhizome and root oxygen during tidal submergence. PLANT, CELL & ENVIRONMENT 2011; 34:2083-92. [PMID: 21819414 DOI: 10.1111/j.1365-3040.2011.02405.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Gas films on hydrophobic surfaces of leaves of some wetland plants can improve O(2) and CO(2) exchange when completely submerged during floods. Here we investigated the in situ aeration of rhizomes of cordgrass (Spartina anglica) during natural tidal submergence, with focus on the role of leaf gas films on underwater gas exchange. Underwater net photosynthesis was also studied in controlled laboratory experiments. In field experiments, O(2) microelectrodes were inserted into rhizomes and pO(2) measured throughout two tidal submergence events; one during daylight and one during night-time. Plants had leaf gas films intact or removed. Rhizome pO(2) dropped significantly during complete submergence and most severely during night. Leaf gas films: (1) enhanced underwater photosynthesis and pO(2) in rhizomes remained above 10 kPa during submergence in light; and (2) facilitated O(2) entry from the water into leaves so that rhizome pO(2) was about 5 kPa during darkness. This study is the first in situ demonstration of the beneficial effects of leaf gas films on internal aeration in a submerged wetland plant. Leaf gas films likely contribute to submergence tolerance of S. anglica and this feature is expected to also benefit other wetland plant species when submerged.
Collapse
Affiliation(s)
- Anders Winkel
- School of Plant Biology (M084), Faculty of Natural and Agricultural Sciences, The University of Western Australia, Crawley, WA 6009, Australia.
| | | | | |
Collapse
|
14
|
Colmer TD, Winkel A, Pedersen O. A perspective on underwater photosynthesis in submerged terrestrial wetland plants. AOB PLANTS 2011; 2011:plr030. [PMID: 22476500 PMCID: PMC3249690 DOI: 10.1093/aobpla/plr030] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Accepted: 11/23/2011] [Indexed: 05/03/2023]
Abstract
BACKGROUND AND AIMS Wetland plants inhabit flood-prone areas and therefore can experience episodes of complete submergence. Submergence impedes exchange of O(2) and CO(2) between leaves and the environment, and light availability is also reduced. The present review examines limitations to underwater net photosynthesis (P(N)) by terrestrial (i.e. usually emergent) wetland plants, as compared with submerged aquatic plants, with focus on leaf traits for enhanced CO(2) acquisition. SCOPE Floodwaters are variable in dissolved O(2), CO(2), light and temperature, and these parameters influence underwater P(N) and the growth and survival of submerged plants. Aquatic species possess morphological and anatomical leaf traits that reduce diffusion limitations to CO(2) uptake and thus aid P(N) under water. Many aquatic plants also have carbon-concentrating mechanisms to increase CO(2) at Rubisco. Terrestrial wetland plants generally lack the numerous beneficial leaf traits possessed by aquatic plants, so submergence markedly reduces P(N). Some terrestrial species, however, produce new leaves with a thinner cuticle and higher specific leaf area, whereas others have leaves with hydrophobic surfaces so that gas films are retained when submerged; both improve CO(2) entry. CONCLUSIONS Submergence inhibits P(N) by terrestrial wetland plants, but less so in species that produce new leaves under water or in those with leaf gas films. Leaves with a thinner cuticle, or those with gas films, have improved gas diffusion with floodwaters, so that underwater P(N) is enhanced. Underwater P(N) provides sugars and O(2) to submerged plants. Floodwaters often contain dissolved CO(2) above levels in equilibrium with air, enabling at least some P(N) by terrestrial species when submerged, although rates remain well below those in air.
Collapse
Affiliation(s)
- Timothy D. Colmer
- School of Plant Biology, The University of Western Australia, Crawley 6009, WA, Australia
| | - Anders Winkel
- School of Plant Biology, The University of Western Australia, Crawley 6009, WA, Australia
- Freshwater Biological Laboratory, University of Copenhagen, Helsingørsgade 51, 3400 Hillerød, Denmark
| | - Ole Pedersen
- School of Plant Biology, The University of Western Australia, Crawley 6009, WA, Australia
- Freshwater Biological Laboratory, University of Copenhagen, Helsingørsgade 51, 3400 Hillerød, Denmark
| |
Collapse
|
15
|
Pedersen O, Pulido C, Rich SM, Colmer TD. In situ O2 dynamics in submerged Isoetes australis: varied leaf gas permeability influences underwater photosynthesis and internal O2. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:4691-700. [PMID: 21841181 PMCID: PMC3170561 DOI: 10.1093/jxb/err193] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Revised: 05/17/2011] [Accepted: 05/18/2011] [Indexed: 05/19/2023]
Abstract
A unique type of vernal pool are those formed on granite outcrops, as the substrate prevents percolation so that water accumulates in depressions when precipitation exceeds evaporation. The O(2) dynamics of small, shallow vernal pools with dense populations of Isoetes australis were studied in situ, and the potential importance of the achlorophyllous leaf bases to underwater net photosynthesis (P(N)) and radial O(2) loss to sediments is highlighted. O(2) microelectrodes were used in situ to monitor pO(2) in leaves, shallow sediments, and water in four vernal pools. The role of the achlorophyllous leaf bases in gas exchange was evaluated in laboratory studies of underwater P(N), loss of tissue water, radial O(2) loss, and light microscopy. Tissue and sediment pO(2) showed large diurnal amplitudes and internal O(2) was more similar to sediment pO(2) than water pO(2). In early afternoon, sediment pO(2) was often higher than tissue pO(2) and although sediment O(2) declined substantially during the night, it did not become anoxic. The achlorophyllous leaf bases were 34% of the surface area of the shoots, and enhanced by 2.5-fold rates of underwater P(N) by the green portions, presumably by increasing the surface area for CO(2) entry. In addition, these leaf bases would contribute to loss of O(2) to the surrounding sediments. Numerous species of isoetids, seagrasses, and rosette-forming wetland plants have a large proportion of the leaf buried in sediments and this study indicates that the white achlorophyllous leaf bases may act as an important area of entry for CO(2), or exit for O(2), with the surrounding sediment.
Collapse
Affiliation(s)
- Ole Pedersen
- Freshwater Biological Laboratory, Department of Biology, University of Copenhagen, Helsingørsgade 51, DK-3400 Hillerød, Denmark.
| | | | | | | |
Collapse
|
16
|
Møller CL, Sand-Jensen K. High sensitivity of Lobelia dortmanna to sediment oxygen depletion following organic enrichment. THE NEW PHYTOLOGIST 2011; 190:320-331. [PMID: 21175638 DOI: 10.1111/j.1469-8137.2010.03584.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
• Lobelia dortmanna thrives in oligotrophic, softwater lakes thanks to O(2) and CO(2) exchange across roots and uptake of sediment nutrients. We hypothesize that low gas permeability of leaves constrains Lobelia to pristine habitats because plants go anoxic in the dark if O(2) vanishes from sediments. • We added organic matter to sediments and followed O(2) dynamics in plants and sediments using microelectrodes. To investigate plant stress, nutrient content and photosynthetic capacity of leaves were measured. • Small additions of organic matter triggered O(2) depletion and accumulation of NH(4)(+), Fe(2+) and CO(2) in sediments. O(2) in leaf lacunae fluctuated from above air saturation in the light to anoxia late in the dark in natural sediments, but organic enrichment prolonged anoxia because of higher O(2) consumption and restricted uptake from the water. Leaf N and P dropped below minimum thresholds for cell function in enriched sediments and was accompanied by critically low chlorophyll and photosynthesis. • We propose that anoxic stress restricts ATP formation and constrains transfer of nutrients to leaves. Brief anoxia in sediments and leaf lacunae late at night is a recurring summer phenomenon in Lobelia populations, but increased input of organic matter prolongs anoxia and reduces survival.
Collapse
Affiliation(s)
- Claus Lindskov Møller
- Freshwater Biological Laboratory, Biological Institute, University of Copenhagen, Hillerød, Denmark.
| | | |
Collapse
|