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Natale S, Peralta Ogorek LL, Caracciolo L, Morosinotto T, van Amerongen H, Casolo V, Pedersen O, Nardini A. Net O 2 exchange rates under dark and light conditions across different stem compartments. THE NEW PHYTOLOGIST 2024; 243:72-81. [PMID: 38703003 DOI: 10.1111/nph.19782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 04/02/2024] [Indexed: 05/06/2024]
Abstract
Woody plants display some photosynthetic activity in stems, but the biological role of stem photosynthesis and the specific contributions of bark and wood to carbon uptake and oxygen evolution remain poorly understood. We aimed to elucidate the functional characteristics of chloroplasts in stems of different ages in Fraxinus ornus. Our investigation employed diverse experimental approaches, including microsensor technology to assess oxygen production rates in whole stem, bark, and wood separately. Additionally, we utilized fluorescence lifetime imaging microscopy (FLIM) to characterize the relative abundance of photosystems I and II (PSI : PSII chlorophyll ratio) in bark and wood. Our findings revealed light-induced increases in O2 production in whole stem, bark, and wood. We present the radial profile of O2 production in F. ornus stems, demonstrating the capability of stem chloroplasts to perform light-dependent electron transport. Younger stems exhibited higher light-induced O2 production and dark respiration rates than older ones. While bark emerged as the primary contributor to net O2 production under light conditions, our data underscored that wood chloroplasts are also photosynthetically active. The FLIM analysis unveiled a lower PSI abundance in wood than in bark, suggesting stem chloroplasts are not only active but also acclimate to the spectral composition of light reaching inner compartments.
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Affiliation(s)
- Sara Natale
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, Trieste, 34127, Italy
- Dipartimento di Biologia, Università di Padova, Via Ugo Bassi 58B, Padova, 35121, Italy
| | - Lucas Léon Peralta Ogorek
- The Freshwater Biological Laboratory, Department of Biology, University of Copenhagen, Universitetsparken 4, Copenhagen, 2100, Denmark
- School of Biosciences, Sutton Bonington Campus, University of Nottingham, Loughborough, LE12 5RD, UK
| | - Ludovico Caracciolo
- Laboratory of Biophysics, Wageningen University & Research, PO Box 8128, 6700 ET, Wageningen, the Netherlands
| | - Tomas Morosinotto
- Dipartimento di Biologia, Università di Padova, Via Ugo Bassi 58B, Padova, 35121, Italy
| | - Herbert van Amerongen
- Laboratory of Biophysics, Wageningen University & Research, PO Box 8128, 6700 ET, Wageningen, the Netherlands
- MicroSpectroscopy Research Facility at Wageningen University & Research, Stippeneng 4, 6708 WE, Wageningen, the Netherlands
| | - Valentino Casolo
- Dipartimento di Scienze Agroalimentari, Ambientali e Animali, Università di Udine, Sezione di Biologia Vegetale, Via delle Scienze 91, Udine, 33100, Italy
| | - Ole Pedersen
- The Freshwater Biological Laboratory, Department of Biology, University of Copenhagen, Universitetsparken 4, Copenhagen, 2100, Denmark
- School of Biological Sciences, The University of Western Australia, Perth, WA, 6009, Australia
| | - Andrea Nardini
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, Trieste, 34127, Italy
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Salomón RL, Helm J, Gessler A, Grams TEE, Hilman B, Muhr J, Steppe K, Wittmann C, Hartmann H. The quandary of sources and sinks of CO2 efflux in tree stems-new insights and future directions. TREE PHYSIOLOGY 2024; 44:tpad157. [PMID: 38214910 DOI: 10.1093/treephys/tpad157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 12/12/2023] [Indexed: 01/13/2024]
Abstract
Stem respiration (RS) substantially contributes to the return of photo assimilated carbon to the atmosphere and, thus, to the tree and ecosystem carbon balance. Stem CO2 efflux (ECO2) is often used as a proxy for RS. However, this metric has often been challenged because of the uncertain origin of CO2 emitted from the stem due to post-respiratory processes. In this Insight, we (i) describe processes affecting the quantification of RS, (ii) review common methodological approaches to quantify and model RS and (iii) develop a research agenda to fill the most relevant knowledge gaps that we identified. Dissolution, transport and accumulation of respired CO2 away from its production site, reassimilation of respired CO2 via stem photosynthesis and the enzyme phosphoenolpyruvate carboxylase, axial CO2 diffusion in the gas phase, shifts in the respiratory substrate and non-respiratory oxygen (O2) consumption are the most relevant processes causing divergence between RS and measured stem gas exchange (ECO2 or O2 influx, IO2). Two common methodological approaches to estimate RS, namely the CO2 mass balance approach and the O2 consumption technique, circumvent some of these processes but have yielded inconsistent results regarding the fate of respired CO2. Stem respiration modelling has recently progressed at the organ and tree levels. However, its implementation in large-scale models, commonly operated from a source-driven perspective, is unlikely to reflect adequate mechanisms. Finally, we propose hypotheses and approaches to advance the knowledge of the stem carbon balance, the role of sap pH on RS, the reassimilation of respired CO2, RS upscaling procedures, large-scale RS modelling and shifts in respiratory metabolism during environmental stress.
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Affiliation(s)
- Roberto L Salomón
- Universidad Politécnica de Madrid (UPM), Departamento de Sistemas y Recursos Naturales, Research Group FORESCENT, Antonio Novais 10, 28040, Madrid, Spain
- Department of Plants and Crops, Laboratory of Plant Ecology, Ghent University, Faculty of Bioscience Engineering, Coupure Links 653, 9000 Ghent, Belgium
| | - Juliane Helm
- Max-Planck-Institute for Biogeochemistry, Biogeochemical Processes, Hans-Knöll-Str. 10, 07743 Jena, Germany
- Department of Environmental Sciences - Botany, Basel University, Schönbeinstr. 6, Basel CH-4056, Switzerland
| | - Arthur Gessler
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zurcherstrasse 111, 8903 Birmensdorf, Switzerland
- Institute of Terrestrial Ecosystems, ETH Zürich, Rämistrasse 101, 8902 Zurich, Switzerland
| | - Thorsten E E Grams
- Technical University of Munich, Ecophysiology of Plants, Land Surface - Atmosphere Interactions, Von-Carlowitz-Platz 2, 85354 Freising, Germany
| | - Boaz Hilman
- Max-Planck-Institute for Biogeochemistry, Biogeochemical Processes, Hans-Knöll-Str. 10, 07743 Jena, Germany
| | - Jan Muhr
- Department of Forest Botany and Tree Physiology, Laboratory for Radioisotopes, Georg-August Universität Göttingen, Büsgenweg 2, 37077 Göttingen, Germany
| | - Kathy Steppe
- Department of Plants and Crops, Laboratory of Plant Ecology, Ghent University, Faculty of Bioscience Engineering, Coupure Links 653, 9000 Ghent, Belgium
| | - Christiane Wittmann
- Faculty of Biology, Botanical Garden, University of Duisburg-Essen, Universitätsstrasse 5, 45117 Essen, Germany
| | - Henrik Hartmann
- Max-Planck-Institute for Biogeochemistry, Biogeochemical Processes, Hans-Knöll-Str. 10, 07743 Jena, Germany
- Institute for Forest Protection, Julius Kühn Institute Federal Research Centre for Cultivated Plants, Erwin-Baur-Straße 27, 06484 Quedlinburg, Germany
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Nie W, Dong Y, Liu Y, Tan C, Wang Y, Yuan Y, Ma J, An S, Liu J, Xiao W, Jiang Z, Jia Z, Wang J. Climatic responses and variability in bark anatomical traits of 23 Picea species. FRONTIERS IN PLANT SCIENCE 2023; 14:1201553. [PMID: 37528988 PMCID: PMC10388546 DOI: 10.3389/fpls.2023.1201553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 06/26/2023] [Indexed: 08/03/2023]
Abstract
In woody plants, bark is an important protective tissue which can participate in photosynthesis, manage water loss, and transport assimilates. Studying the bark anatomical traits can provide insight into plant environmental adaptation strategies. However, a systematic understanding of the variability in bark anatomical traits and their drivers is lacking in woody plants. In this study, the bark anatomical traits of 23 Picea species were determined in a common garden experiment. We analyzed interspecific differences and interpreted the patterns in bark anatomical traits in relation to phylogenetic relationships and climatic factors of each species according to its global distribution. The results showed that there were interspecific differences in bark anatomical traits of Picea species. Phloem thickness was positively correlated with parenchyma cell size, possibly related to the roles of parenchyma cells in the radial transport of assimilates. Sieve cell size was negatively correlated with the radial diameter of resin ducts, and differences in sieve cells were possibly related to the formation and expansion of resin ducts. There were no significant phylogenetic signals for any bark anatomical trait, except the tangential diameter of resin ducts. Phloem thickness and parenchyma cell size were affected by temperature-related factors of their native range, while sieve cell size was influenced by precipitation-related factors. Bark anatomical traits were not significantly different under wet and dry climates. This study makes an important contribution to our understanding of variability in bark anatomical traits among Picea species and their ecological adaptations.
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Affiliation(s)
- Wen Nie
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing, China
| | - Yao Dong
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing, China
| | - Yifu Liu
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing, China
| | - Cancan Tan
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing, China
| | - Ya Wang
- State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China
| | - Yanchao Yuan
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing, China
| | - Jianwei Ma
- Research Institute of Forestry of Xiaolong Mountain, Gansu Provincial Key Laboratory of Secondary Forest Cultivation, Tianshui, China
| | - Sanping An
- Research Institute of Forestry of Xiaolong Mountain, Gansu Provincial Key Laboratory of Secondary Forest Cultivation, Tianshui, China
| | - Jianfeng Liu
- State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China
| | - Wenfa Xiao
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing, China
| | - Zeping Jiang
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing, China
| | - Zirui Jia
- State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China
| | - Junhui Wang
- State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China
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Ye C, Zeng Q, Hu K, Fang D, Hölscher D, Du H, Shi Y, Zhou Y, Berninger F, Mei T, Zhou G. Partitioning of respired CO 2 in newly sprouted Moso bamboo culms. FRONTIERS IN PLANT SCIENCE 2023; 14:1154232. [PMID: 37152132 PMCID: PMC10158728 DOI: 10.3389/fpls.2023.1154232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 03/30/2023] [Indexed: 05/09/2023]
Abstract
Stem respiration (R s) plays a vital role in ecosystem carbon cycling. However, the measured efflux on the stem surface (E s) is not always in situ R s but only part of it. A previously proposed mass balance framework (MBF) attempted to explore the multiple partitioning pathways of R s, including sap-flow-transported and internal storage of R s, in addition to E s. This study proposed stem photosynthesis as an additional partitioning pathway to the MBF. Correspondingly, a double-chamber apparatus was designed and applied on newly sprouted Moso bamboo (Phyllostachys edulis) in leafless and leaved stages. R s of newly sprouted bamboo were twice as high in the leafless stage (7.41 ± 2.66 μmol m-2 s-1) than in the leaved stage (3.47 ± 2.43 μmol m-2 s-1). E s accounted for ~80% of R s, while sap flow may take away ~2% of R s in both leafless and leaved stages. Culm photosynthesis accounted for ~9% and 13% of R s, respectively. Carbon sequestration from culm photosynthesis accounted for approximately 2% of the aboveground bamboo biomass in the leafless stage. High culm photosynthesis but low sap flow during the leafless stage and vice versa during the leaved stage make bamboo an outstanding choice for exploring the MBF.
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Affiliation(s)
- Chongyu Ye
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Lin’an, Zhejiang, China
- Key Laboratory of Carbon Cycling in Forest Ecosystems and Carbon Sequestration of Zhejiang Province, Zhejiang A&F University, Lin’an, Zhejiang, China
- College of Environmental and Resource Sciences, Zhejiang A&F University, Lin’an, Zhejiang, China
| | - Qiangfa Zeng
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Lin’an, Zhejiang, China
- Key Laboratory of Carbon Cycling in Forest Ecosystems and Carbon Sequestration of Zhejiang Province, Zhejiang A&F University, Lin’an, Zhejiang, China
- College of Environmental and Resource Sciences, Zhejiang A&F University, Lin’an, Zhejiang, China
| | - Keda Hu
- College of Environmental and Resource Sciences, Zhejiang A&F University, Lin’an, Zhejiang, China
| | - Dongming Fang
- Jiyang College, Zhejiang A&F University, Zhuji, Zhejiang, China
| | - Dirk Hölscher
- Tropical Silviculture and Forest Ecology, University of Göttingen, Göttingen, Germany
| | - Huaqiang Du
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Lin’an, Zhejiang, China
- Key Laboratory of Carbon Cycling in Forest Ecosystems and Carbon Sequestration of Zhejiang Province, Zhejiang A&F University, Lin’an, Zhejiang, China
- College of Environmental and Resource Sciences, Zhejiang A&F University, Lin’an, Zhejiang, China
| | - Yongjun Shi
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Lin’an, Zhejiang, China
- Key Laboratory of Carbon Cycling in Forest Ecosystems and Carbon Sequestration of Zhejiang Province, Zhejiang A&F University, Lin’an, Zhejiang, China
- College of Environmental and Resource Sciences, Zhejiang A&F University, Lin’an, Zhejiang, China
| | - Yufeng Zhou
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Lin’an, Zhejiang, China
- Key Laboratory of Carbon Cycling in Forest Ecosystems and Carbon Sequestration of Zhejiang Province, Zhejiang A&F University, Lin’an, Zhejiang, China
- College of Environmental and Resource Sciences, Zhejiang A&F University, Lin’an, Zhejiang, China
| | - Frank Berninger
- Department of Environmental and Biological Sciences, University of Eastern Finland, Joensuu, Finland
| | - Tingting Mei
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Lin’an, Zhejiang, China
- Key Laboratory of Carbon Cycling in Forest Ecosystems and Carbon Sequestration of Zhejiang Province, Zhejiang A&F University, Lin’an, Zhejiang, China
- College of Environmental and Resource Sciences, Zhejiang A&F University, Lin’an, Zhejiang, China
- *Correspondence: Tingting Mei, ; Guomo Zhou,
| | - Guomo Zhou
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Lin’an, Zhejiang, China
- Key Laboratory of Carbon Cycling in Forest Ecosystems and Carbon Sequestration of Zhejiang Province, Zhejiang A&F University, Lin’an, Zhejiang, China
- College of Environmental and Resource Sciences, Zhejiang A&F University, Lin’an, Zhejiang, China
- *Correspondence: Tingting Mei, ; Guomo Zhou,
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Liu R, Feng X, Li C, Ma J, Wang Y, Li Y. The Importance of Stem Photosynthesis for Two Desert Shrubs Across Different Groundwater Depths. FRONTIERS IN PLANT SCIENCE 2022; 13:804786. [PMID: 35371182 PMCID: PMC8965657 DOI: 10.3389/fpls.2022.804786] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 02/10/2022] [Indexed: 06/01/2023]
Abstract
Water availability could alter multiple ecophysiological processes such as water use strategy, photosynthesis, and respiration, thereby modifying plant water use and carbon gain. However, a lack of field observations hinders our understanding of how water availability affects stem photosynthesis at both organ and plant levels of desert shrubs. In this study, we measured gas exchange and oxygen stable isotopes to quantify water sources, stem recycling photosynthesis, and whole-plant carbon balance in two coexisting Haloxylon species (Haloxylon ammodendron and Haloxylon persicum) at different groundwater depths in the Gurbantonggut Desert. The overall aim of the study was to analyze and quantify the important role of stem recycling photosynthesis for desert shrubs (Haloxylon species) under different groundwater depths. The results showed that (1) regardless of changes in groundwater depth, H. ammodendron consistently used groundwater and H. persicum used deep soil water as their main water source, with greater than 75% of xylem water being derived from groundwater and deep soil water for the two species, respectively; (2) stem recycling photosynthesis refixed 72-81% of the stem dark respiration, and its contribution to whole-plant carbon assimilation was 10-21% for the two species; and (3) deepened groundwater increased stem water use efficiency and its contribution to whole-plant carbon assimilation in H. persicum but not in H. ammodendron. Our study provided observational evidence that deepened groundwater depth induced H. persicum to increase stem recycling photosynthetic capacity and a greater contribution to whole-plant carbon assimilation, but this did not occur on H. ammodendron. Our study indicates that stem recycling photosynthesis may play an important role in the survival of desert shrubs in drought conditions.
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Affiliation(s)
- Ran Liu
- State Key Lab of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, China
- Fukang National Station of Observation and Research for Desert Ecosystem, Xinjiang, China
| | - Xiaolong Feng
- State Key Lab of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, China
- Fukang National Station of Observation and Research for Desert Ecosystem, Xinjiang, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Congjuan Li
- Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, China
| | - Jie Ma
- State Key Lab of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, China
- Fukang National Station of Observation and Research for Desert Ecosystem, Xinjiang, China
| | - Yugang Wang
- State Key Lab of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, China
- Fukang National Station of Observation and Research for Desert Ecosystem, Xinjiang, China
| | - Yan Li
- State Key Lab of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, China
- Fukang National Station of Observation and Research for Desert Ecosystem, Xinjiang, China
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Liu J, Sun C, Zhai FF, Li Z, Qian Y, Gu L, Sun Z. Proteomic insights into the photosynthetic divergence between bark and leaf chloroplasts in Salix matsudana. TREE PHYSIOLOGY 2021; 41:2142-2152. [PMID: 33987679 DOI: 10.1093/treephys/tpab055] [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: 02/29/2020] [Accepted: 04/07/2021] [Indexed: 06/12/2023]
Abstract
Bark chloroplasts play important roles in carbon balancing by recycling internal stem CO2 into assimilated carbon. The photosynthetic response of bark chloroplasts to interior stem environments has been studied recently in woody plants. However, the molecular regulatory mechanisms underlying specific characteristics of bark photosynthesis remain unclear. To address this knowledge gap, differences in the structure, photosynthetic activity and protein expression profiles between bark and leaf chloroplasts were investigated in Salix matsudana in this study. Bark chloroplasts exhibited broader and lower grana stacks and higher levels of starch relative to leaf chloroplasts. Concomitantly, decreased oxygen evolution rates and decreased saturated radiation point were observed in bark chloroplasts. Furthermore, a total of 293 differentially expressed proteins (DEPs) were identified in bark and leaf chloroplast profile comparisons. These DEPs were significantly enriched in photosynthesis-related biological processes or Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways associated with photosynthesis. All 116 DEPs within the KEGG pathways associated with photosynthesis light reactions were downregulated in bark chloroplasts, including key proteins responsible for chlorophyll synthesis, light energy harvesting, nonphotochemical quenching, linear electron transport and photophosphorylation. Interestingly, seven upregulated proteins involved in dark reactions were identified in bark chloroplasts that comprised two kinds of malic enzymes typical of C4-type photosynthesis. These results provide comprehensive proteomic evidence to understand the low photochemical capability of bark chloroplasts and suggest that bark chloroplasts might fix CO2 derived from malate decarboxylation.
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Affiliation(s)
- Junxiang Liu
- State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of the State Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, P.R. China
| | - Chao Sun
- State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of the State Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, P.R. China
| | - Fei-Fei Zhai
- School of Architectural and Artistic Design, Henan Polytechnic University, Jiaozuo, Henan 454000, P.R. China
| | - Zhenjian Li
- State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of the State Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, P.R. China
| | - Yongqiang Qian
- State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of the State Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, P.R. China
| | - Lin Gu
- State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of the State Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, P.R. China
| | - Zhenyuan Sun
- State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of the State Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, P.R. China
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De Roo L, Salomón RL, Steppe K. Woody tissue photosynthesis reduces stem CO 2 efflux by half and remains unaffected by drought stress in young Populus tremula trees. PLANT, CELL & ENVIRONMENT 2020; 43:981-991. [PMID: 31884680 DOI: 10.1111/pce.13711] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 12/19/2019] [Accepted: 12/21/2019] [Indexed: 06/10/2023]
Abstract
A substantial portion of locally respired CO2 in stems can be assimilated by chloroplast-containing tissues. Woody tissue photosynthesis (Pwt ) therefore plays a major role in the stem carbon balance. To study the impact of Pwt on stem carbon cycling along a gradient of water availability, stem CO2 efflux (EA ), xylem CO2 concentration ([CO2 ]), and xylem water potential (Ψxylem ) were measured in 4-year-old Populus tremula L. trees exposed to drought stress and different regimes of light exclusion of woody tissues. Under well-watered conditions, local Pwt decreased EA up to 30%. Axial CO2 diffusion (Dax ) induced by distant Pwt caused an additional decrease in EA of up to 25% and limited xylem [CO2 ] build-up. Under drought stress, absolute decreases in EA driven by Pwt remained stable, denoting that Pwt was not affected by drought. At the end of the dry period, when transpiration was low, local Pwt and Dax offset 20% and 10% of stem respiration on a daily basis, respectively. These results highlight (a) the importance of Pwt for an adequate interpretation of EA measurements and (b) homeostatic Pwt along a drought stress gradient, which might play a crucial role to fuel stem metabolism when leaf carbon uptake and phloem transport are limited.
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Affiliation(s)
- Linus De Roo
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Roberto Luis Salomón
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Kathy Steppe
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
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Rosell JA. Bark in Woody Plants: Understanding the Diversity of a Multifunctional Structure. Integr Comp Biol 2020; 59:535-547. [PMID: 31120526 DOI: 10.1093/icb/icz057] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Most biological structures carry out multiple functions. Focusing on only one function to make adaptive inferences overlooks that manifold selection pressures and tradeoffs shape the characteristics of a multifunctional structure. Focusing on single functions can only lead to a partial picture of the causes underlying diversity and the evolutionary origin of the structure in question. I illustrate this discussion using bark as a study case. Bark comprises all the tissues surrounding the xylem in woody plants. Broadly, bark includes an inner and mostly living region and an outer, dead one. Of all plant structures, bark has the most complex anatomical structure and ontogenetic origin involving two (and often three) different meristems. Traditionally, the wide diversity in bark traits, mainly bark thickness, has been interpreted as the result of the selective pressures imposed by fire regime. However, recent research has shown that explanations based on fire regime cannot account for salient patterns of bark variation globally including the very strong inner bark thickness-stem diameter scaling, which is likely due to metabolic needs, and the very high intracommunity variation in total, inner, and outer bark thickness, and in inner:outer proportions. Moreover, explanations based on fire disregard that in addition to fire protection, bark carries out several other crucial functions for plants including translocation of photosynthates; storage of starch, soluble sugars, water, and other compounds; protection from herbivores, pathogens, and high temperatures; wound closure, as well as mechanical support, photosynthesis, and likely being involved in xylem embolism repair. All these functions are crucial for plant performance and are involved in synergistic (e.g., storage of water and insulation) and trade-off relationships (e.g., protection from fire vs photosynthetic activity). Focusing on only one of these functions, protection from fire has provided an incomplete picture of the selective forces shaping bark diversity and has severely hindered our incipient understanding of the functional ecology of this crucial region of woody stems. Applying a multifunctional perspective to the study of bark will allow us to address why we observe such high intracommunity variation in bark traits, why some bark trait combinations are ontogenetically impossible or penalized by selection, how bark is coordinated functionally with other plant parts, and as a result, to understand how bark contributes to the vast diversity of plant ecological strategies across the globe.
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Affiliation(s)
- Julieta A Rosell
- Laboratorio Nacional de Ciencias de la Sostenibilidad, Instituto de Ecología, Universidad Nacional Autónoma de México, Apartado Postal 70-275, Ciudad de México 04510, Mexico
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Brazel AJ, Ó'Maoiléidigh DS. Photosynthetic activity of reproductive organs. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:1737-1754. [PMID: 30824936 DOI: 10.1093/jxb/erz033] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 02/07/2019] [Indexed: 05/06/2023]
Abstract
During seed development, carbon is reallocated from maternal tissues to support germination and subsequent growth. As this pool of resources is depleted post-germination, the plant begins autotrophic growth through leaf photosynthesis. Photoassimilates derived from the leaf are used to sustain the plant and form new organs, including other vegetative leaves, stems, bracts, flowers, fruits, and seeds. In contrast to the view that reproductive tissues act only as resource sinks, many studies demonstrate that flowers, fruits, and seeds are photosynthetically active. The photosynthetic contribution to development is variable between these reproductive organs and between species. In addition, our understanding of the developmental control of photosynthetic activity in reproductive organs is vastly incomplete. A further complication is that reproductive organ photosynthesis (ROP) appears to be particularly important under suboptimal growth conditions. Therefore, the topic of ROP presents the community with a challenge to integrate the fields of photosynthesis, development, and stress responses. Here, we attempt to summarize our understanding of the contribution of ROP to development and the molecular mechanisms underlying its control.
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Affiliation(s)
- Ailbhe J Brazel
- Max Planck Institute for Plant Breeding Research, Cologne, Germany
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