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Keret R, Drew DM, Hills PN. Xylem cell size regulation is a key adaptive response to water deficit in Eucalyptus grandis. TREE PHYSIOLOGY 2024; 44:tpae068. [PMID: 38896029 PMCID: PMC11247191 DOI: 10.1093/treephys/tpae068] [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: 02/14/2024] [Revised: 06/06/2024] [Accepted: 06/18/2024] [Indexed: 06/21/2024]
Abstract
Future climatic scenarios forecast increasingly frequent droughts that will pose substantial consequences on tree mortality. In light of this, drought-tolerant eucalypts have been propagated; however, the severity of these conditions will invoke adaptive responses, impacting the commercially valuable wood properties. To determine what mechanisms govern the wood anatomical adaptive response, highly controlled drought experiments were conducted in Eucalyptus grandis W. Hill ex Maiden, with the tree physiology and transcriptome closely monitored. In response to water deficit, E. grandis displays an isohydric stomatal response to conserve water and enable stem growth to continue, albeit at a reduced rate. Maintaining gaseous exchange is likely a critical short-term response that drives the formation of hydraulically safer xylem. For instance, the development of significantly smaller fibers and vessels was found to increase cellular density, thereby promoting drought tolerance through improved functional redundancy, as well as implosion and cavitation resistance. The transcriptome was explored to identify the molecular mechanisms responsible for controlling xylem cell size during prolonged water deficit. Downregulation of genes associated with cell wall remodeling and the biosynthesis of cellulose, hemicellulose and pectin appeared to coincide with a reduction in cellular enlargement during drought. Furthermore, transcript levels of NAC and MYB transcription factors, vital for cell wall component biosynthesis, were reduced, while those linked to lignification increased. The upregulation of EgCAD and various peroxidases under water deficit did not correlate with an increased lignin composition. However, with the elevated cellular density, a higher lignin content per xylem cross-sectional area was observed, potentially enhancing hydraulic safety. These results support the requirement for higher density, drought-adapted wood as a long-term adaptive response in E. grandis, which is largely influenced by the isohydric stomatal response coupled with cellular expansion-related molecular processes.
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Affiliation(s)
- Rafael Keret
- Institute for Plant Biotechnology, Department of Genetics, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch 7602, South Africa
- Department of Forestry and Wood Sciences, Stellenbosch University, Bosman St, Stellenbosch 7599, South Africa
| | - David M Drew
- Department of Forestry and Wood Sciences, Stellenbosch University, Bosman St, Stellenbosch 7599, South Africa
| | - Paul N Hills
- Institute for Plant Biotechnology, Department of Genetics, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch 7602, South Africa
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2
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Keret R, Schliephack PM, Stangler DF, Seifert T, Kahle HP, Drew DM, Hills PN. An open-source machine-learning approach for obtaining high-quality quantitative wood anatomy data from E. grandis and P. radiata xylem. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2024; 340:111970. [PMID: 38163623 DOI: 10.1016/j.plantsci.2023.111970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 12/26/2023] [Accepted: 12/27/2023] [Indexed: 01/03/2024]
Abstract
Quantitative wood anatomy is a subfield in dendrochronology that requires effective open-source image analysis tools. In this research, the bioimage analysis software QuPath (v0.4.4) is introduced as a candidate for accurately quantifying the cellular properties of the xylem in an automated manner. Additionally, the potential of QuPath to detect the transition of early- to latewood tracheids over the growing season was evaluated to assess a potential application in dendroecological studies. Various algorithms in QuPath were optimized to quantify different xylem cell types in Eucalyptus grandis and the transition of early- to latewood tracheids in Pinus radiata. These algorithms were coded into cell detection scripts for automatic quantification of stem microsections and compared to a manually curated method to assess the accuracy of the cell detections. The automatic cell detection approach, using QuPath, has been validated to be reproducible with an acceptable error when assessing fibers, vessels, early- and latewood tracheids. However, further optimization for parenchyma is still required. This proposed method developed in QuPath provides a scalable and accurate approach for quantifying anatomical features in stem microsections. With minor amendments to the detection and classification algorithms, this strategy is likely to be viable in other plant species.
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Affiliation(s)
- Rafael Keret
- Institute for Plant Biotechnology, Department of Genetics, Stellenbosch University, Private Bag X1, Matieland 7602, Stellenbosch, South Africa; Department of Forestry and Wood Sciences, Stellenbosch University, Bosman St, 7599, Stellenbosch central, South Africa
| | - Paul M Schliephack
- Chair of Forest Growth and Dendroecology, Institute of Forest Sciences, University of Freiburg, Tennenbacher Str. 4, Freiburg im Breisgau, Germany
| | - Dominik F Stangler
- Chair of Forest Growth and Dendroecology, Institute of Forest Sciences, University of Freiburg, Tennenbacher Str. 4, Freiburg im Breisgau, Germany
| | - Thomas Seifert
- Department of Forestry and Wood Sciences, Stellenbosch University, Bosman St, 7599, Stellenbosch central, South Africa; Chair of Forest Growth and Dendroecology, Institute of Forest Sciences, University of Freiburg, Tennenbacher Str. 4, Freiburg im Breisgau, Germany
| | - Hans-Peter Kahle
- Chair of Forest Growth and Dendroecology, Institute of Forest Sciences, University of Freiburg, Tennenbacher Str. 4, Freiburg im Breisgau, Germany
| | - David M Drew
- Department of Forestry and Wood Sciences, Stellenbosch University, Bosman St, 7599, Stellenbosch central, South Africa.
| | - Paul N Hills
- Institute for Plant Biotechnology, Department of Genetics, Stellenbosch University, Private Bag X1, Matieland 7602, Stellenbosch, South Africa
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Zhang X, Liu H, Rademacher T. Higher latewood to earlywood ratio increases resistance of radial growth to severe droughts in larch. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:169165. [PMID: 38101621 DOI: 10.1016/j.scitotenv.2023.169165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Revised: 12/05/2023] [Accepted: 12/05/2023] [Indexed: 12/17/2023]
Abstract
As drought has caused great losses of tree growth across the world, the mechanism of how trees adapt to drought has been extensively investigated. However, how trees change their late- to earlywood ratio (LER) to adapt to severe drought events remains poorly understood. We used a network of Larix principis-rupprechtii earlywood and latewood width data from 1979 to 2018, covering most of the distribution of planted larch across North China, to investigate how latewood proportion affected trees' resistance to drought. The interactions among LER, minimum temperature, vapor pressure deficit (VPD), growing season length, and their contributions to drought resistant (Rt) were estimated using structural equation models. The results show a significant increase in LER of the juvenile wood throughout the first 15 growth rings after which it stabilizes. The LER decreased significantly with elevation for the juvenile wood. March-May temperature and VPD were the main determinant in the LER of mature wood. The sensitivity of radial growth to droughts was positively changed with LER when LER was below 0.50, but negatively changed with LER when LER is above 0.50. We confirmed that high LER increases resistance of tree growth to severe droughts in L. principis-rupprechtii. Our results highlight that a higher proportion of latewood is formed in dry years, and this high drought sensitivity of LER in turn led to an increased resistance to drought. This combination of reduced radial growth during dry years, while the latewood proportion remains increases maybe an adaptive strategy of larch trees to cope with severe droughts.
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Affiliation(s)
- Xianliang Zhang
- College of Forestry, Hebei Agricultural University, Baoding, China; College of Urban and Environmental Sciences, and PKU-Saihanba Station, Peking University, Beijing, China
| | - Hongyan Liu
- College of Urban and Environmental Sciences, and PKU-Saihanba Station, Peking University, Beijing, China.
| | - Tim Rademacher
- Institut des Sciences de la Forêt Tempérée, Université du Québec en Outaouais, J0V 1V0 Ripon, Québec, Canada; Centre ACER, J2S 0B8 Saint-Hyacinthe, Québec, Canada
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Segovia-Rivas A, Olson ME. Temperature and Turgor "Limitation" and Environmental "Control" in Xylem Biology and Dendrochronology. Integr Comp Biol 2023; 63:1364-1375. [PMID: 37550219 DOI: 10.1093/icb/icad110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Revised: 07/23/2023] [Accepted: 07/28/2023] [Indexed: 08/09/2023] Open
Abstract
Trees and other woody plants are immensely ecologically important, making it essential to understand the causes of relationships between tree structure and function. To help these efforts, we highlight persistent traditions in plant biology of appealing to environmental factors "limiting" or "controlling" woody plant features. Examples include the idea that inevitable drops in cell turgor with plant height limit cell expansion and thus leaf size and tree height; that low temperatures prohibit lignification of cells and thus the growth of woody plants at high elevation; and notions from dendrochronology and related fields that climate factors such as rainfall and temperature "control" growth ring features. We show that notions of "control," "limitation," and the like imply that selection would favor a given trait value, but that these would-be favored values are developmentally impossible to produce. Such "limitation" scenarios predict trait frequency distributions that are very narrow and are abruptly curtailed at the upper limit of developmental possibility (the right-hand side of the distribution). Such distributions have, to our knowledge, never been observed, so we see little empirical support for "limitation" hypotheses. We suggest that, as a more productive starting point, plant biologists should examine adaptation hypotheses, in which developmental possibility is wide (congruent with the wide ranges of trait variation that really are observed), but only some of the possible variants are favored. We suggest that (1) the traditional the proximate/ultimate causation distinction, (2) purging scenarios of teleology/anthropomorphism, and (3) stating hypotheses in terms of developmental potential and natural selection are three simple ways of making "limitation" hypotheses clearer with regard to biological process and thus empirically testable.
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Affiliation(s)
- Alí Segovia-Rivas
- Instituto de Biología, , Universidad Nacional Autónoma de México, Tercer Circuito sn de Ciudad Universitaria, Ciudad de México 04510, Mexico
| | - Mark E Olson
- Instituto de Biología, , Universidad Nacional Autónoma de México, Tercer Circuito sn de Ciudad Universitaria, Ciudad de México 04510, Mexico
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Silvestro R, Zeng Q, Buttò V, Sylvain JD, Drolet G, Mencuccini M, Thiffault N, Yuan S, Rossi S. A longer wood growing season does not lead to higher carbon sequestration. Sci Rep 2023; 13:4059. [PMID: 36906726 PMCID: PMC10008533 DOI: 10.1038/s41598-023-31336-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 03/09/2023] [Indexed: 03/13/2023] Open
Abstract
A reliable assessment of forest carbon sequestration depends on our understanding of wood ecophysiology. Within a forest, trees exhibit different timings and rates of growth during wood formation. However, their relationships with wood anatomical traits remain partially unresolved. This study evaluated the intra-annual individual variability in growth traits in balsam fir [Abies balsamea (L.) Mill.]. We collected wood microcores weekly from April to October 2018 from 27 individuals in Quebec (Canada) and prepared anatomical sections to assess wood formation dynamics and their relationships with the anatomical traits of the wood cells. Xylem developed in a time window ranging from 44 to 118 days, producing between 8 and 79 cells. Trees with larger cell production experienced a longer growing season, with an earlier onset and later ending of wood formation. On average, each additional xylem cell lengthened the growing season by 1 day. Earlywood production explained 95% of the variability in xylem production. More productive individuals generated a higher proportion of earlywood and cells with larger sizes. Trees with a longer growing season produced more cells but not more biomass in the wood. Lengthening the growing season driven by climate change may not lead to enhanced carbon sequestration from wood production.
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Affiliation(s)
- Roberto Silvestro
- Laboratoire sur les écosystemes terrestres boreaux, Département des Sciences Fondamentales, Université du Québec à Chicoutimi, 555 boulevard de l'Université, Chicoutimi, QC, G7H2B1, Canada.
| | - Qiao Zeng
- Guangdong Open Laboratory of Geospatial Information Technology and Application, Guangzhou Institute of Geography, Guangdong Academy of Sciences, Guangzhou, 510070, People's Republic of China
| | - Valentina Buttò
- Forest Research Institute, Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, QC, Canada
| | - Jean-Daniel Sylvain
- Direction de la recherche forestiere Ministère des Forêts, de la Faune et des Parcs, Québec, QC, G1P3W8, Canada
| | - Guillaume Drolet
- Direction de la recherche forestiere Ministère des Forêts, de la Faune et des Parcs, Québec, QC, G1P3W8, Canada
| | - Maurizio Mencuccini
- Centre de Recerca Ecològica i Aplicacions Forestals (CREAF), 08193, Bellaterra, Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig de Lluis Companys 23, 08010, Barcelona, Spain
| | - Nelson Thiffault
- Canadian Wood Fibre Centre, Canadian Forest Service, Natural Resources Canada, 1055, du P.E.P.S., Sainte-Foy Stn., P.O. Box 10380, Quebec, QC, G1V 4C7, Canada.,Centre for Forest Research, Faculty of Forestry, Geography and Geomatics, Université Laval, 2405 rue de la Terrasse, Quebec, QC, G1V 0A6, Canada
| | - Shaoxiong Yuan
- Guangdong Open Laboratory of Geospatial Information Technology and Application, Guangzhou Institute of Geography, Guangdong Academy of Sciences, Guangzhou, 510070, People's Republic of China
| | - Sergio Rossi
- Laboratoire sur les écosystemes terrestres boreaux, Département des Sciences Fondamentales, Université du Québec à Chicoutimi, 555 boulevard de l'Université, Chicoutimi, QC, G7H2B1, Canada
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Rademacher T, Fonti P, LeMoine JM, Fonti MV, Bowles F, Chen Y, Eckes-Shephard AH, Friend AD, Richardson AD. Insights into source/sink controls on wood formation and photosynthesis from a stem chilling experiment in mature red maple. THE NEW PHYTOLOGIST 2022; 236:1296-1309. [PMID: 35927942 DOI: 10.1111/nph.18421] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 07/30/2022] [Indexed: 06/15/2023]
Abstract
Whether sources or sinks control wood growth remains debated with a paucity of evidence from mature trees in natural settings. Here, we altered carbon supply rate in stems of mature red maples (Acer rubrum) within the growing season by restricting phloem transport using stem chilling; thereby increasing carbon supply above and decreasing carbon supply below the restrictions, respectively. Chilling successfully altered nonstructural carbon (NSC) concentrations in the phloem without detectable repercussions on bulk NSC in stems and roots. Ring width responded strongly to local variations in carbon supply with up to seven-fold differences along the stem of chilled trees; however, concurrent changes in the structural carbon were inconclusive at high carbon supply due to large local variability of wood growth. Above chilling-induced bottlenecks, we also observed higher leaf NSC concentrations, reduced photosynthetic capacity, and earlier leaf coloration and fall. Our results indicate that the cambial sink is affected by carbon supply, but within-tree feedbacks can downregulate source activity, when carbon supply exceeds demand. Such feedbacks have only been hypothesized in mature trees. Consequently, these findings constitute an important advance in understanding source-sink dynamics, suggesting that mature red maples operate close to both source- and sink-limitation in the early growing season.
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Affiliation(s)
- Tim Rademacher
- Harvard Forest, Harvard University, Petersham, MA, 01366, USA
- School of Informatics, Computing and Cyber Systems and Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA
- Institut des Sciences de la Forêt Tempérée, Université du Québec en Outaouais, Ripon, J0V 1V0, QC, Canada
| | - Patrick Fonti
- Swiss Federal Research Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, 8903, Switzerland
| | - James M LeMoine
- School of Informatics, Computing and Cyber Systems and Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA
| | - Marina V Fonti
- Swiss Federal Research Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, 8903, Switzerland
- Institute of Ecology and Geography, Siberian Federal University, Krasnoyarsk, 660041, Russia
| | | | - Yizhao Chen
- Department of Geography, University of Cambridge, Cambridge, CB2 1BY, UK
| | - Annemarie H Eckes-Shephard
- Department of Geography, University of Cambridge, Cambridge, CB2 1BY, UK
- Department of Physical Geography and Ecosystem Science, Lund University, Lund, 223 62, Sweden
| | - Andrew D Friend
- Department of Geography, University of Cambridge, Cambridge, CB2 1BY, UK
| | - Andrew D Richardson
- School of Informatics, Computing and Cyber Systems and Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA
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Variability in frost occurrence under climate change and consequent risk of damage to trees of western Quebec, Canada. Sci Rep 2022; 12:7220. [PMID: 35508611 PMCID: PMC9068889 DOI: 10.1038/s41598-022-11105-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 04/08/2022] [Indexed: 12/02/2022] Open
Abstract
Climate change affects timings, frequency, and intensity of frost events in northern ecosystems. However, our understanding of the impacts that frost will have on growth and survival of plants is still limited. When projecting the occurrence of frost, the internal variability and the different underlying physical formulations are two major sources of uncertainty of climate models. We use 50 climate simulations produced by a single-initial large climate ensemble and five climate simulations produced by different pairs of global and regional climate models based on the concentration pathway (RCP 8.5) over a latitudinal transect covering the temperate and boreal ecosystems of western Quebec, Canada, during 1955–2099 to provide a first-order estimate of the relative importance of these two sources of uncertainty on the occurrence of frost, i.e. when air temperature is < 0 °C, and their potential damage to trees. The variation in the date of the last spring frost was larger by 21 days (from 46 to 25 days) for the 50 climate simulations compared to the 5 different pairs of climate models. When considering these two sources of uncertainty in an eco-physiological model simulating the timings of budbreak for trees of northern environment, results show that 20% of climate simulations expect that trees will be exposed to frost even in 2090. Thus, frost damage to trees remains likely under global warming.
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Eckes-Shephard AH, Ljungqvist FC, Drew DM, Rathgeber CBK, Friend AD. Wood Formation Modeling - A Research Review and Future Perspectives. FRONTIERS IN PLANT SCIENCE 2022; 13:837648. [PMID: 35401628 PMCID: PMC8984029 DOI: 10.3389/fpls.2022.837648] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 01/24/2022] [Indexed: 05/29/2023]
Abstract
Wood formation has received considerable attention across various research fields as a key process to model. Historical and contemporary models of wood formation from various disciplines have encapsulated hypotheses such as the influence of external (e.g., climatic) or internal (e.g., hormonal) factors on the successive stages of wood cell differentiation. This review covers 17 wood formation models from three different disciplines, the earliest from 1968 and the latest from 2020. The described processes, as well as their external and internal drivers and their level of complexity, are discussed. This work is the first systematic cataloging, characterization, and process-focused review of wood formation models. Remaining open questions concerning wood formation processes are identified, and relate to: (1) the extent of hormonal influence on the final tree ring structure; (2) the mechanism underlying the transition from earlywood to latewood in extratropical regions; and (3) the extent to which carbon plays a role as "active" driver or "passive" substrate for growth. We conclude by arguing that wood formation models remain to be fully exploited, with the potential to contribute to studies concerning individual tree carbon sequestration-storage dynamics and regional to global carbon sequestration dynamics in terrestrial vegetation models.
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Affiliation(s)
| | - Fredrik Charpentier Ljungqvist
- Department of History, Stockholm University, Stockholm, Sweden
- Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
- Swedish Collegium for Advanced Study, Uppsala, Sweden
| | - David M. Drew
- Department of Forest and Wood Science, Stellenbosch University, Stellenbosch, South Africa
| | - Cyrille B. K. Rathgeber
- Université de Lorraine, AgroParisTech, INRAE, SILVA, Nancy, France
- Swiss Federal Research Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland
| | - Andrew D. Friend
- Department of Geography, University of Cambridge, Cambridge, United Kingdom
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