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Stanfield RC, Forrestel EJ, Elmendorf KE, Bagshaw SB, Bartlett MK. Phloem anatomy predicts berry sugar accumulation across 13 wine-grape cultivars. FRONTIERS IN PLANT SCIENCE 2024; 15:1360381. [PMID: 38576794 PMCID: PMC10991835 DOI: 10.3389/fpls.2024.1360381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 02/19/2024] [Indexed: 04/06/2024]
Abstract
Introduction Climate change is impacting the wine industry by accelerating ripening processes due to warming temperatures, especially in areas of significant grape production like California. Increasing temperatures accelerate the rate of sugar accumulation (measured in ⁰Brix) in grapes, however this presents a problem to wine makers as flavor profiles may need more time to develop properly. To alleviate the mismatch between sugar accumulation and flavor compounds, growers may sync vine cultivars with climates that are most amenable to their distinct growing conditions. However, the traits which control such cultivar specific climate adaptation, especially for ⁰Brix accumulation rate, are poorly understood. Recent studies have shown that higher rates of fruit development and sugar accumulation are predicted by larger phloem areas in different organs of the plant. Methods Here we test this phloem area hypothesis using a common garden experiment in the Central Valley of Northern California using 18 cultivars of the common grapevine (Vitis vinifera) and assess the grape berry sugar accumulation rates as a function of phloem area in leaf and grape organs. Results We find that phloem area in the leaf petiole organ as well as the berry pedicel is a significant predictor of ⁰Brix accumulation rate across 13 cultivars and that grapes from warm climates overall have larger phloem areas than those from hot climates. In contrast, other physiological traits such as photosynthetic assimilation and leaf water potential did not predict berry accumulation rates. Discussion As hot climate cultivars have lower phloem areas which would slow down brix accumulation, growers may have inadvertently been selecting this trait to align flavor development with sugar accumulation across the common cultivars tested. This work highlights a new trait that can be easily phenotyped (i.e., petiole phloem area) and be used for growers to match cultivar more accurately with the temperature specific climate conditions of a growing region to obtain satisfactory sugar accumulation and flavor profiles.
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Affiliation(s)
- Ryan C. Stanfield
- Department of Biological Sciences, California State University, Stanislaus, Turlock, CA, United States
- Department of Viticulture & Enology, University of California Davis, Davis, CA, United States
| | - Elisabeth J. Forrestel
- Department of Viticulture & Enology, University of California Davis, Davis, CA, United States
| | - Kayla E. Elmendorf
- Department of Viticulture & Enology, University of California Davis, Davis, CA, United States
| | - Sophia B. Bagshaw
- Department of Viticulture & Enology, University of California Davis, Davis, CA, United States
| | - Megan K. Bartlett
- Department of Viticulture & Enology, University of California Davis, Davis, CA, United States
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Shi J, Yang B, Wang H, Wu Y, He F, Dong J, Qin G. The combined contamination of nano-polystyrene and nanoAg: Uptake, translocation and ecotoxicity effects on willow saplings. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 905:167291. [PMID: 37742955 DOI: 10.1016/j.scitotenv.2023.167291] [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: 07/12/2023] [Revised: 09/19/2023] [Accepted: 09/21/2023] [Indexed: 09/26/2023]
Abstract
Nanoplastics (NPLs) and nanoAg (AgNPs) are emerging contaminants commonly detected in aquatic and terrestrial environments due to their widespread use in various domains. However, their uptake, translocation, and toxic effects on plants in cooccurrence environments remain largely unexplored. Therefore, a hydroponic experiment was conducted using 100 nm NPLs (1 mg/L and 10 mg/L), AgNPs (100 μg/L and 1000 μg/L) and saplings of willow (Salix matsudana 'J172') to investigate absorption, translocation and the physio-biochemical responses of the plants. The results indicated that NPLs and AgNPs were agglomerated with each other in solutions. NPLs not only penetrated the roots of the saplings but also translocated to the branches and leaves through xylem ducts. However, AgNPs was only detected in the roots, suggesting that the internalization of nanoparticles in plants depends on the properties and types of particles themselves. The combined exposure to NPLs and AgNPs selectively affected the absorption and distribution of K, Ca, Mg and Fe, resulting in inhibited saplings growth and photosynthesis. Furthermore, the presence of NPLs and AgNPs induced oxidative damage and stimulated the antioxidant stress system in the plants. This study provides novel insights into the internalization and ecotoxicological mechanisms of NPLs and AgNPs in woody vascular plants.
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Affiliation(s)
- Jiaxing Shi
- School of Water Conservancy and Environment, University of Jinan, Jinan 250022, China
| | - Baoshan Yang
- School of Water Conservancy and Environment, University of Jinan, Jinan 250022, China; Shandong Provincial Engineering Technology Research Center for Ecological Carbon Sink and Capture Utilization, Jinan 250022, China
| | - Hui Wang
- School of Water Conservancy and Environment, University of Jinan, Jinan 250022, China; Shandong Provincial Engineering Technology Research Center for Ecological Carbon Sink and Capture Utilization, Jinan 250022, China.
| | - Yaxin Wu
- School of Water Conservancy and Environment, University of Jinan, Jinan 250022, China
| | - Fei He
- Jinan Environmental Research Academy, Jinan 250098, China
| | - Jinhao Dong
- School of Water Conservancy and Environment, University of Jinan, Jinan 250022, China
| | - Guanghua Qin
- Shandong Academy of Forestry, Jinan 250014, China
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Prats KA, Fanton AC, Brodersen CR, Furze ME. Starch depletion in the xylem and phloem ray parenchyma of grapevine stems under drought. AOB PLANTS 2023; 15:plad062. [PMID: 37899975 PMCID: PMC10601394 DOI: 10.1093/aobpla/plad062] [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: 04/12/2023] [Accepted: 08/29/2023] [Indexed: 10/31/2023]
Abstract
While nonstructural carbohydrate (NSC) storage can support long-lived woody plants during abiotic stress, the timing and extent of their use are less understood, as are the thresholds for cell mortality as NSCs and water supplies are consumed. Here, we combine physiological and imaging tools to study the response of Vitis riparia to a 6-week experimental drought. We focused on the spatial and temporal dynamics of starch consumption and cell viability in the xylem and phloem of the stem. Starch dynamics were further corroborated with enzymatic starch digestion and X-ray microcomputed tomography imaging. Starch depletion in the stems of droughted plants was detected after 2 weeks and continued over time. We observed distinct differences in starch content and cell viability in the xylem and phloem. By the end of the drought, nearly all the starch was consumed in the phloem ray parenchyma (98 % decrease), and there were almost no metabolically active cells in the phloem. In contrast, less starch was consumed in the xylem ray parenchyma (30 % decrease), and metabolically active cells remained in the ray and vessel-associated parenchyma in the xylem. Our data suggest that the higher proportion of living cells in the phloem and cambium, combined with smaller potential NSC storage area, rapidly depleted starch, which led to cell death. In contrast, the larger cross-sectional area of the xylem ray parenchyma with higher NSC storage and lower metabolically active cell populations depleted starch at a slower pace. Why NSC source-sink relationships between xylem and phloem do not allow for a more uniform depletion of starch in ray parenchyma over time is unclear. Our data help to pinpoint the proximate and ultimate causes of plant death during prolonged drought exposure and highlight the need to consider the influence of within-organ starch dynamics and cell mortality on abiotic stress response.
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Affiliation(s)
- Kyra A Prats
- Department of Botany and Plant Pathology, Purdue University, 915 Mitch Daniels Blvd, West Lafayette, IN 47907, USA
- Center for Plant Biology, Purdue University, 915 Mitch Daniels Blvd, West Lafayette, IN 47907, USA
| | - Ana C Fanton
- Ecophysiologie et Génomique Fonctionnelle de la Vigne, INRAE, 210 Chemin de Leysotte, Villenave-d’Ornon 33140, France
| | - Craig R Brodersen
- School of the Environment, Yale University, 195 Prospect St, New Haven, CT 06511, USA
| | - Morgan E Furze
- Department of Botany and Plant Pathology, Purdue University, 915 Mitch Daniels Blvd, West Lafayette, IN 47907, USA
- Center for Plant Biology, Purdue University, 915 Mitch Daniels Blvd, West Lafayette, IN 47907, USA
- Department of Forestry and Natural Resources, Purdue University, 715 Mitch Daniels Blvd, West Lafayette, IN 47907, USA
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Chen P, Li L, Xia S, Zhang R, Zhang R, Zeng XM, Shuai D, Liu Y, Li ZG. Enhancement patterns of potassium on nitrogen transport and functional genes in cotton vary with nitrogen levels. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2023; 335:111824. [PMID: 37572966 DOI: 10.1016/j.plantsci.2023.111824] [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: 05/30/2023] [Revised: 07/17/2023] [Accepted: 08/09/2023] [Indexed: 08/14/2023]
Abstract
The application of potassium (K) in conjunction with nitrogen (N) has been shown to enhance N use efficiency. However, there is still a need for further understanding of the optimal ratios and molecular regulatory mechanisms, particularly in soil-cotton systems. Here, a field trial was conducted, involving varying rates of N and K, alongside pot and hydroponic experiments. The objective was to assess the impact of N-K interaction on the absorption, transport and distribution of N in cotton. The results showed that K supply at 90 and 240 kg ha-1 had a beneficial impact on N uptake and distribution to both seed and lint, resulting in the highest N use efficiency ranging from 22% to 62% and yield improvements from 20% to 123%. The increase in stem and root diameters, rather than the quantify of xylem vessels and phloem sieve tubes, facilitated the uptake and transport of N due to the provision of K. At the molecular level, K supply upregulated the expression levels of genes encoding GhNRT2.1 transporter and GhSLAH3 channel in cotton roots to promote N uptake and GhNRT1.5/NPF7.3 genes to transport N to shoot under low-N conditions. However, under high-N conditions, K supply induced anion channel genes (GhSLAH4) of roots to promote N uptake and genes encoding GhNRT1.5/NPF7.3 and GhNRT1.8/NPF7.2 transporters to facilitate NO3- unloading from xylem to mesophyll cell in high-N plants. Furthermore, K supply resulted in the upregulation of gene expression for GhGS2 in leaves, while simultaneously downregulating the expression of GhNADH-GOGAT, GhGDH1 and GhGDH3 genes in high-N roots. The enzyme activities of nitrite reductase and glutamine synthetase increased and glutamate dehydrogenase decreased, but the concentration of NO3- and soluble protein exhibited a significant increase and free amino acid decreased in the shoots subsequent to K supply.
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Affiliation(s)
- Peng Chen
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
| | - Linyang Li
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
| | - Shujie Xia
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
| | - Runhua Zhang
- Wuhan Academy of Agriculture Science and Technology, Vegetable Research Institute, Wuhan 430345, China
| | - Runqin Zhang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
| | - Xiao-Min Zeng
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Du Shuai
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Yi Liu
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; Center of Conservation Biology / Economic Botany / Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Wuhan 430074, China.
| | - Zhi-Guo Li
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China.
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Consequences of the Reproductive Effort of Dioecious Taxus baccata L. Females in a Generative Bud Removal Experiment-Important Role of Nitrogen in Female Reproduction. Int J Mol Sci 2022; 23:ijms232214225. [PMID: 36430702 PMCID: PMC9695432 DOI: 10.3390/ijms232214225] [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: 10/24/2022] [Revised: 11/04/2022] [Accepted: 11/15/2022] [Indexed: 11/19/2022] Open
Abstract
Dioecious species differ in the pattern and intensity of male and female reproductive investments. We aimed to determine whether female shoots deprived of generative buds show biochemical features, indicating their less-pronounced reproductive effort. For this purpose, the same branches of mature Taxus baccata females were deprived of generative organs. In the second and third years of the experiment, measurements were made in every season from the control and bud-removed shoots of females and control males. Bud removal caused an increase in nitrogen concentration almost to the level detected in the needles of male specimens, but only in current-year needles. Moreover, differences between male and control female shoots were present in the C:N ratio and increment biomass, but they disappeared when bud removal was applied to females. Additionally, between-sex differences were observed for content of phenolic compounds, carbon and starch, and SLA, independent of the female shoot reproductive effort. The study revealed that nitrogen uptake in seeds and arils may explain the lower nitrogen level and consequently the lower growth rate of females compared to males. At the same time, reproduction did not disturb carbon level in adjacent tissues, and two hypotheses explaining this phenomenon have been put forward.
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McDowell NG, Ball M, Bond‐Lamberty B, Kirwan ML, Krauss KW, Megonigal JP, Mencuccini M, Ward ND, Weintraub MN, Bailey V. Processes and mechanisms of coastal woody-plant mortality. GLOBAL CHANGE BIOLOGY 2022; 28:5881-5900. [PMID: 35689431 PMCID: PMC9544010 DOI: 10.1111/gcb.16297] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 05/24/2022] [Indexed: 05/26/2023]
Abstract
Observations of woody plant mortality in coastal ecosystems are globally widespread, but the overarching processes and underlying mechanisms are poorly understood. This knowledge deficiency, combined with rapidly changing water levels, storm surges, atmospheric CO2 , and vapor pressure deficit, creates large predictive uncertainty regarding how coastal ecosystems will respond to global change. Here, we synthesize the literature on the mechanisms that underlie coastal woody-plant mortality, with the goal of producing a testable hypothesis framework. The key emergent mechanisms underlying mortality include hypoxic, osmotic, and ionic-driven reductions in whole-plant hydraulic conductance and photosynthesis that ultimately drive the coupled processes of hydraulic failure and carbon starvation. The relative importance of these processes in driving mortality, their order of progression, and their degree of coupling depends on the characteristics of the anomalous water exposure, on topographic effects, and on taxa-specific variation in traits and trait acclimation. Greater inundation exposure could accelerate mortality globally; however, the interaction of changing inundation exposure with elevated CO2 , drought, and rising vapor pressure deficit could influence mortality likelihood. Models of coastal forests that incorporate the frequency and duration of inundation, the role of climatic drivers, and the processes of hydraulic failure and carbon starvation can yield improved estimates of inundation-induced woody-plant mortality.
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Affiliation(s)
- Nate G. McDowell
- Atmospheric Sciences and Global Change DivisionPacific Northwest National LabRichlandWashingtonUSA
- School of Biological SciencesWashington State UniversityPullmanWashingtonUSA
| | - Marilyn Ball
- Plant Science Division, Research School of BiologyThe Australian National UniversityActonAustralian Capital TerritoryAustralia
| | - Ben Bond‐Lamberty
- Joint Global Change Research Institute, Pacific Northwest National LaboratoryCollege ParkMarylandUSA
| | - Matthew L. Kirwan
- Virginia Institute of Marine Science, William & MaryGloucester PointVirginiaUSA
| | - Ken W. Krauss
- U.S. Geological Survey, Wetland and Aquatic Research CenterLafayetteLouisianaUSA
| | | | - Maurizio Mencuccini
- ICREA, Passeig Lluís Companys 23BarcelonaSpain
- CREAFCampus UAB, BellaterraBarcelonaSpain
| | - Nicholas D. Ward
- Marine and Coastal Research LaboratoryPacific Northwest National LaboratorySequimWashingtonUSA
- School of OceanographyUniversity of WashingtonSeattleWashingtonUSA
| | - Michael N. Weintraub
- Department of Environmental SciencesUniversity of ToledoToledoOhioUSA
- Biological Sciences DivisionPacific Northwest National LaboratoryWashingtonUSA
| | - Vanessa Bailey
- Biological Sciences DivisionPacific Northwest National LaboratoryWashingtonUSA
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7
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Cho N, Agossou C, Kim E, Lim JH, Hwang T, Kang S. Recent field findings and modeling on non-structural carbohydrates (NSCs): How to synthesize? ECOL INFORM 2022. [DOI: 10.1016/j.ecoinf.2022.101695] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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8
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Li M, Gu H, Lam SS, Sonne C, Peng W. Deposition-mediated phytoremediation of nitrogen oxide emissions. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 308:119706. [PMID: 35798191 DOI: 10.1016/j.envpol.2022.119706] [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: 04/06/2022] [Revised: 06/06/2022] [Accepted: 06/29/2022] [Indexed: 06/15/2023]
Abstract
The growing global population and use of natural resources lead to significant air pollution. Nitrogen oxide emissions is a potential killer threatening human health requiring focus and remediation using vegetation being efficient and cheap. Here we review the mechanisms of removing nitrogen oxides by dry deposition of plants, discussing the principle of leaf absorption of pollutants and factors affecting the removal of nitrogen oxides providing a theoretical basis for the selection of urban greening vegetation.
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Affiliation(s)
- Mengzhen Li
- Henan Province International Collaboration Lab of Forest Resources Utilization, School of Forestry, Henan Agricultural University, Zhengzhou 450002, China
| | - Haping Gu
- Henan Province International Collaboration Lab of Forest Resources Utilization, School of Forestry, Henan Agricultural University, Zhengzhou 450002, China
| | - Su Shiung Lam
- Universiti Malaysia Terengganu, Higher Institution Centre of Excellence (HICoE), Institute of Tropical Aquaculture and Fisheries; 21030 Kuala Nerus, Terengganu, Malaysia
| | - Christian Sonne
- Aarhus University, Department of Bioscience, Arctic Research Centre (ARC), Frederiksborgvej 399, PO Box 358, DK-4000 Roskilde, Denmark
| | - Wanxi Peng
- Henan Province International Collaboration Lab of Forest Resources Utilization, School of Forestry, Henan Agricultural University, Zhengzhou 450002, China.
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9
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Nakad M, Domec JC, Sevanto S, Katul G. Radial-axial transport coordination enhances sugar translocation in the phloem vasculature of plants. PLANT PHYSIOLOGY 2022; 189:2061-2071. [PMID: 35588257 PMCID: PMC9343002 DOI: 10.1093/plphys/kiac231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 04/27/2022] [Indexed: 05/21/2023]
Abstract
Understanding mass transport of photosynthates in the phloem of plants is necessary for predicting plant carbon allocation, productivity, and responses to water and thermal stress. Several hypotheses about optimization of phloem structure and function and limitations of phloem transport under drought have been proposed and tested with models and anatomical data. However, the true impact of radial water exchange of phloem conduits with their surroundings on mass transport of photosynthates has not been addressed. Here, the physics of the Munch mechanism of sugar transport is re-evaluated to include local variations in viscosity resulting from the radial water exchange in two dimensions (axial and radial) using transient flow simulations. Model results show an increase in radial water exchange due to a decrease in sap viscosity leading to increased sugar front speed and axial mass transport across a wide range of phloem conduit lengths. This increase is around 40% for active loaders (e.g. crops) and around 20% for passive loaders (e.g. trees). Thus, sugar transport operates more efficiently than predicted by previous models that ignore these two effects. A faster front speed leads to higher phloem resiliency under drought because more sugar can be transported with a smaller pressure gradient.
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Affiliation(s)
| | - Jean-Christophe Domec
- Bordeaux Sciences Agro, UMR 1391 INRA-ISPA, Gradignan 33175, France
- Nicholas School of the Environment, Duke University, Durham, North Carolina 27708, USA
| | - Sanna Sevanto
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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10
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Proença PL, Carvalho LB, Campos EV, Fraceto LF. Fluorescent labeling as a strategy to evaluate uptake and transport of polymeric nanoparticles in plants. Adv Colloid Interface Sci 2022; 305:102695. [PMID: 35598536 DOI: 10.1016/j.cis.2022.102695] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 05/05/2022] [Accepted: 05/08/2022] [Indexed: 11/01/2022]
Abstract
The use of biodegradable nanopolymers in agriculture offers an excellent alternative for the efficient delivery of agrochemicals that promote plant protection and development. However, tracking of these systems inside plants requires complex probe tagging strategies. In addition to providing a basis for better understanding such nanostructures to optimize delivery system design, these probes allow monitoring the migration of nanoparticles through plant tissues, and determine accumulation sites. Thus, these probes are powerful tools that can be used to quantify and visualize nanoparticle accumulation in plant cells and tissues. This review is an overview of the methods involved in labeling nanocarriers, mainly based on polymeric matrices, for the delivery of nanoagrochemicals and the recent advances in this field.
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11
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Maghsoudi N, Doroodmand MM. Specific Ionic Recognition Using Fig's Xylem/Phloem Vessel as a Novel and Applicable Device: Lab-on-a Xylem/Phloem. ACS OMEGA 2022; 7:20596-20604. [PMID: 35755353 PMCID: PMC9218978 DOI: 10.1021/acsomega.2c00589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 05/17/2022] [Indexed: 06/15/2023]
Abstract
A novel and specific detection system using voltage-stimulating ion transport through fig xylem/phloem vessels as a new lab-on-a xylem/phloem substrate was introduced. The voltage drove the ion flux through the vessels by a sinusoidal waveform with very low frequency (2.70 ± 0.05 kHz, n = 10) and voltage amplitude between 0.0 and 1.0 kV (vs total applied potential) with positive and negative polarities depending on cation and anion separation, respectively. The recorded potential induced by the applied potential was considered as a fingerprint electrical potential stimulator during reliable recognition of different ionic species. The system possessed some different characteristics such as (i) prominent figures of merit with linear ranges between 5.0 and 1200.0 (±0.7, n = 10) ng mL-1 (correlation coefficient, R 2, >0.99) for each ionic species and (ii) improved detection limits via tracing electrical current and conductance gradient (as the sensitive detection systems), while testing 50.0 ng mL-1 of different salts as cationic and anionic species. The reliability of the system was evidenced via focusing on at least 60 independent cationic and anionic species during introducing a 70-membered distinct array-based bio-substrate device. This process not only showed great method applicability for specific determination with acceptable figures of merit but also resulted in introducing a software database for direct detection and recognition of various ionic analyses. The introduced detection/separation device competed with other spectroscopic/electrochemical systems due to the specific and simultaneous recognition of great ranges of ionic species in different real samples at ultratrace levels.
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van den Herik B, ten Tusscher K. Undirected Sucrose Efflux Mitigation by the FT-Like SP6A Preferentially Enhances Tuber Resource Partitioning. FRONTIERS IN PLANT SCIENCE 2022; 13:817909. [PMID: 35615135 PMCID: PMC9125184 DOI: 10.3389/fpls.2022.817909] [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: 11/18/2021] [Accepted: 03/18/2022] [Indexed: 06/15/2023]
Abstract
The yield of harvestable plant organs depends on overall photosynthetic output and the subsequent distribution of the produced assimilates from source leaves across different sink organs. In this study, we aimed to obtain, using a two-sink transport model, mechanistic understanding of how the interplay between sink and pathway properties together determines sink resource partitioning. As a working example, we analyzed the partitioning of resources within potato plants, investigating the determinants of tuber sink yield. Our results indicated that, contrary to earlier studies, with a spatially explicit biophysically detailed model, transport pathway properties significantly affect sink resource partitioning within the physiologically relevant domain. Additionally, we uncovered that xylem flow, through its hydraulic coupling to the phloem, and sucrose efflux along the phloem, also significantly affected resource partitioning. For tubers, it is the cumulative disadvantage compared to sink leaves (distance, xylem flow, and sucrose efflux) that enable an undirected SP6A-mediated reduction of sucrose efflux to preferentially benefit tuber resource partitioning. Combined with the SP6A-mediated sink strength increase, undirected SP6A introduction significantly enhances tuber resource partitioning.
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Salomón RL, De Roo L, Oleksyn J, Steppe K. Mechanistic drivers of stem respiration: A modelling exercise across species and seasons. PLANT, CELL & ENVIRONMENT 2022; 45:1270-1285. [PMID: 34914118 DOI: 10.1111/pce.14246] [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: 08/03/2021] [Revised: 09/22/2021] [Accepted: 12/03/2021] [Indexed: 06/14/2023]
Abstract
Stem respiration (RS ) plays a crucial role in plant carbon budgets. However, its poor understanding limits our ability to model woody tissue and whole-tree respiration. A biophysical model of stem water and carbon fluxes (TReSpire) was calibrated on cedar, maple and oak trees during spring and late summer. For this, stem sap flow, water potential, diameter variation, temperature, CO2 efflux, allometry and biochemistry were monitored. Shoot photosynthesis (PN ) and nonstructural carbohydrates (NSC) were additionally measured to evaluate source-sink relations. The highest RS and stem growth was found in maple and oak during spring, both being seasonally decoupled from PN and [NSC]. Temperature largely affected maintenance respiration (RM ) in the short term, but temperature-normalized RM was highly variable on a seasonal timescale. Overall, most of the respired CO2 radially diffused to the atmosphere (>87%) while the remainder was transported upward with the transpiration stream. The modelling exercise highlights the sink-driven behaviour of RS and the significance of overall metabolic activity on nitrogen (N) allocation patterns and N-normalized respiratory costs to capture RS variability over the long term. These insights should be considered when modelling plant respiration, whose representation is currently biased towards a better understanding of leaf metabolism.
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Affiliation(s)
- Roberto L Salomón
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
- Sistemas Naturales e Historia Forestal, Universidad Politécnica de Madrid, Madrid, Spain
| | - Linus De Roo
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Jacek Oleksyn
- Polish Academy of Sciences, Institute of Dendrology, Körnik, Poland
| | - Kathy Steppe
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
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Hikino K, Danzberger J, Riedel VP, Rehschuh R, Ruehr NK, Hesse BD, Lehmann MM, Buegger F, Weikl F, Pritsch K, Grams TEE. High resilience of carbon transport in long-term drought-stressed mature Norway spruce trees within 2 weeks after drought release. GLOBAL CHANGE BIOLOGY 2022; 28:2095-2110. [PMID: 34927319 DOI: 10.1111/gcb.16051] [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: 06/08/2021] [Accepted: 11/29/2021] [Indexed: 06/14/2023]
Abstract
Under ongoing global climate change, drought periods are predicted to increase in frequency and intensity in the future. Under these circumstances, it is crucial for tree's survival to recover their restricted functionalities quickly after drought release. To elucidate the recovery of carbon (C) transport rates in c. 70-year-old Norway spruce (Picea abies [L.] KARST.) after 5 years of recurrent summer droughts, we conducted a continuous whole-tree 13 C labeling experiment in parallel with watering. We determined the arrival time of current photoassimilates in major C sinks by tracing the 13 C label in stem and soil CO2 efflux, and tips of living fine roots. In the first week after watering, aboveground C transport rates (CTR) from crown to trunk base were still 50% lower in previously drought-stressed trees (0.16 ± 0.01 m h-1 ) compared to controls (0.30 ± 0.06 m h-1 ). Conversely, CTR below ground, that is, from the trunk base to soil CO2 efflux were already similar between treatments (c. 0.03 m h-1 ). Two weeks after watering, aboveground C transport of previously drought-stressed trees recovered to the level of the controls. Furthermore, regrowth of water-absorbing fine roots upon watering was supported by faster incorporation of 13 C label in previously drought-stressed (within 12 ± 10 h upon arrival at trunk base) compared to control trees (73 ± 10 h). Thus, the whole-tree C transport system from the crown to soil CO2 efflux fully recovered within 2 weeks after drought release, and hence showed high resilience to recurrent summer droughts in mature Norway spruce forests. This high resilience of the C transport system is an important prerequisite for the recovery of other tree functionalities and productivity.
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Affiliation(s)
- Kyohsuke Hikino
- Technical University of Munich (TUM), TUM School of Life Sciences, Land Surface-Atmosphere Interactions, Ecophysiology of Plants, Freising, Germany
| | - Jasmin Danzberger
- Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Institute of Biochemical Plant Pathology, Neuherberg, Germany
| | - Vincent P Riedel
- Technical University of Munich (TUM), TUM School of Life Sciences, Land Surface-Atmosphere Interactions, Ecophysiology of Plants, Freising, Germany
| | - Romy Rehschuh
- Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research-Atmospheric Environmental Research (KIT/IMK-IFU), Garmisch-Partenkirchen, Germany
| | - Nadine K Ruehr
- Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research-Atmospheric Environmental Research (KIT/IMK-IFU), Garmisch-Partenkirchen, Germany
| | - Benjamin D Hesse
- Technical University of Munich (TUM), TUM School of Life Sciences, Land Surface-Atmosphere Interactions, Ecophysiology of Plants, Freising, Germany
| | - Marco M Lehmann
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Forest Dynamics, Birmensdorf, Switzerland
| | - Franz Buegger
- Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Institute of Biochemical Plant Pathology, Neuherberg, Germany
| | - Fabian Weikl
- Technical University of Munich (TUM), TUM School of Life Sciences, Land Surface-Atmosphere Interactions, Ecophysiology of Plants, Freising, Germany
- Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Institute of Biochemical Plant Pathology, Neuherberg, Germany
| | - Karin Pritsch
- Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Institute of Biochemical Plant Pathology, Neuherberg, Germany
| | - Thorsten E E Grams
- Technical University of Munich (TUM), TUM School of Life Sciences, Land Surface-Atmosphere Interactions, Ecophysiology of Plants, Freising, Germany
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15
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Stanfield RC, Bartlett MK. Coordination Between Phloem Loading and Structure Maintains Carbon Transport Under Drought. FRONTIERS IN PLANT SCIENCE 2022; 13:787837. [PMID: 35251074 PMCID: PMC8891486 DOI: 10.3389/fpls.2022.787837] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 01/27/2022] [Indexed: 06/14/2023]
Abstract
Maintaining phloem transport under water stress is expected to be crucial to whole-plant drought tolerance, but the traits that benefit phloem function under drought are poorly understood. Nearly half of surveyed angiosperm species, including important crops, use sucrose transporter proteins to actively load sugar into the phloem. Plants can alter transporter abundance in response to stress, providing a potential mechanism for active-loading species to closely regulate phloem loading rates to avoid drought-induced reductions or failures in phloem transport. We developed an integrated xylem-phloem-stomatal model to test this hypothesis by quantifying the joint impacts of transporter kinetics, phloem anatomy, and plant water status on sucrose export to sinks. We parameterized the model with phloem hydraulic resistances and sucrose transporter kinetic parameters compiled from the literature, and simulated loading regulation by allowing loading rates to decline exponentially with phloem pressure to prevent excessive sucrose concentrations from inducing viscosity limitations. In the absence of loading regulation, where loading rates were independent of phloem pressure, most resistance values produced unrealistic phloem pressures owing to viscosity effects, even under well-watered conditions. Conversely, pressure-regulated loading helped to control viscosity buildup and improved export to sinks for both lower and higher resistant phloem pathways, while maintaining realistic phloem pressures. Regulation also allowed for rapid loading and export in wet conditions while maintaining export and viable phloem pressures during drought. Therefore, we expect feedbacks between phloem pressure and loading to be critical to carbon transport in active-loading species, especially under drought, and for transporter kinetics to be strongly coordinated with phloem architecture and plant water status. This work provides an important and underexplored physiological framework to understand the ecophysiology of phloem transport under drought and to enhance the genetic engineering of crop plants.
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Affiliation(s)
- Ryan C. Stanfield
- Department of Viticulture and Enology, University of California, Davis, Davis, CA, United States
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16
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Potkay A, Hölttä T, Trugman AT, Fan Y. Turgor-limited predictions of tree growth, height and metabolic scaling over tree lifespans. TREE PHYSIOLOGY 2022; 42:229-252. [PMID: 34296275 DOI: 10.1093/treephys/tpab094] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 07/18/2021] [Indexed: 06/13/2023]
Abstract
Increasing evidence suggests that tree growth is sink-limited by environmental and internal controls rather than by carbon availability. However, the mechanisms underlying sink-limitations are not fully understood and thus not represented in large-scale vegetation models. We develop a simple, analytically solved, mechanistic, turgor-driven growth model (TDGM) and a phloem transport model (PTM) to explore the mechanics of phloem transport and evaluate three hypotheses. First, phloem transport must be explicitly considered to accurately predict turgor distributions and thus growth. Second, turgor-limitations can explain growth-scaling with size (metabolic scaling). Third, turgor can explain realistic growth rates and increments. We show that mechanistic, sink-limited growth schemes based on plant turgor limitations are feasible for large-scale model implementations with minimal computational demands. Our PTM predicted nearly uniform sugar concentrations along the phloem transport path regardless of phloem conductance, stem water potential gradients and the strength of sink-demands contrary to our first hypothesis, suggesting that phloem transport is not limited generally by phloem transport capacity per se but rather by carbon demand for growth and respiration. These results enabled TDGM implementation without explicit coupling to the PTM, further simplifying computation. We test the TDGM by comparing predictions of whole-tree growth rate to well-established observations (site indices) and allometric theory. Our simple TDGM predicts realistic tree heights, growth rates and metabolic scaling over decadal to centurial timescales, suggesting that tree growth is generally sink and turgor limited. Like observed trees, our TDGM captures tree-size- and resource-based deviations from the classical ¾ power-law metabolic scaling for which turgor is responsible.
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Affiliation(s)
- Aaron Potkay
- Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ 08854, USA
| | - Teemu Hölttä
- Institute for Atmospheric and Earth System Research/Forest Sciences, University of Helsinki, Helsinki FI-00014, Finland
| | - Anna T Trugman
- Department of Geography, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
| | - Ying Fan
- Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ 08854, USA
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17
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Rehschuh R, Rehschuh S, Gast A, Jakab AL, Lehmann MM, Saurer M, Gessler A, Ruehr NK. Tree allocation dynamics beyond heat and hot drought stress reveal changes in carbon storage, belowground translocation and growth. THE NEW PHYTOLOGIST 2022; 233:687-704. [PMID: 34668198 DOI: 10.1111/nph.17815] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 10/12/2021] [Indexed: 06/13/2023]
Abstract
Heatwaves combined with drought affect tree functioning with as yet undetermined legacy effects on carbon (C) and nitrogen (N) allocation. We continuously monitored shoot and root gas exchange, δ13 CO2 of respiration and stem growth in well-watered and drought-treated Pinus sylvestris (Scots pine) seedlings exposed to increasing daytime temperatures (max. 42°C) and evaporative demand. Following stress release, we used 13 CO2 canopy pulse-labeling, supplemented by soil-applied 15 N, to determine allocation to plant compartments, respiration and soil microbial biomass (SMB) over 2.5 wk. Previously heat-treated seedlings rapidly translocated 13 C along the long-distance transport path, to root respiration (Rroot ; 7.1 h) and SMB (3 d). Furthermore, 13 C accumulated in branch cellulose, suggesting secondary growth enhancement. However, in recovering drought-heat seedlings, the mean residence time of 13 C in needles increased, whereas C translocation to Rroot was delayed (13.8 h) and 13 C incorporated into starch rather than cellulose. Concurrently, we observed stress-induced low N uptake and aboveground allocation. C and N allocation during early recovery were affected by stress type and impact. Although C uptake increased quickly in both treatments, drought-heat in combination reduced the above-belowground coupling and starch accumulated in leaves at the expense of growth. Accordingly, C allocation during recovery depends on phloem translocation capacity.
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Affiliation(s)
- Romy Rehschuh
- Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, 82467, Germany
| | - Stephanie Rehschuh
- Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, 82467, Germany
| | - Andreas Gast
- Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, 82467, Germany
| | - Andrea-Livia Jakab
- Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, 82467, Germany
| | - Marco M Lehmann
- Swiss Federal Research Institute WSL, Research Unit Forest Dynamics, Birmensdorf, 8903, Switzerland
| | - Matthias Saurer
- Swiss Federal Research Institute WSL, Research Unit Forest Dynamics, Birmensdorf, 8903, Switzerland
| | - Arthur Gessler
- Swiss Federal Research Institute WSL, Research Unit Forest Dynamics, Birmensdorf, 8903, Switzerland
- Department of Environmental System Sciences, ETH Zurich, Zurich, 8092, Switzerland
| | - Nadine K Ruehr
- Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, 82467, Germany
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18
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Williams CB, Reese Næsborg R, Ambrose AR, Baxter WL, Koch GW, Dawson TE. The dynamics of stem water storage in the tops of Earth's largest trees-Sequoiadendron giganteum. TREE PHYSIOLOGY 2021; 41:2262-2278. [PMID: 34104960 DOI: 10.1093/treephys/tpab078] [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: 04/04/2020] [Accepted: 05/31/2021] [Indexed: 06/12/2023]
Abstract
Water stored in tree stems (i.e., trunks and branches) is an important contributor to transpiration that can improve photosynthetic carbon gain and reduce the probability of cavitation. However, in tall trees, the capacity to store water may decline with height because of chronically low water potentials associated with the gravitational potential gradient. We quantified the importance of elastic stem water storage in the top 5-6 m of large (4.2-5.0 m diameter at breast height, 82.1-86.3 m tall) Sequoiadendron giganteum (Lindley) J. Buchholz (giant sequoia) trees using a combination of architectural measurements and automated sensors that monitored summertime diel rhythms in sap flow, stem diameter and water potential. Stem water storage contributed 1.5-1.8% of water transpired at the tree tops, and hydraulic capacitance ranged from 2.6 to 4.1 l MPa-1 m-3. These values, which are considerably smaller than reported for shorter trees, may be associated with persistently low water potentials imposed by gravity and could indicate a trend of decreasing water storage dynamics with height in tree. Branch diameter contraction and expansion consistently and substantially lagged behind fluxes in water potential and sap flow, which occurred in sync. This lag suggests that the inner bark, which consists mostly of live secondary phloem tissue, was an important hydraulic capacitor, and that hydraulic resistance between xylem and phloem retards water transfer between these tissues. We also measured tree-base sap flux, which lagged behind that measured in trunks near the tree tops, indicating additional storage in the large trunks between these measurement positions. Whole-tree sap flow ranged from 2227 to 3752 l day-1, corroborating previous records for similar-sized giant sequoia and representing the largest yet reported for any individual tree. Despite such extraordinarily high daily water use, we estimate that water stored in tree-top stems contributes minimally to transpiration on typical summer days.
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Affiliation(s)
- Cameron B Williams
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
- Channel Islands National Park, Ventura, CA 93001, USA
- Santa Barbara Botanic Garden, Santa Barbara, CA 93105, USA
| | - Rikke Reese Næsborg
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
- Santa Barbara Botanic Garden, Santa Barbara, CA 93105, USA
| | - Anthony R Ambrose
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
- The Marmot Society, South Lake Tahoe, CA 96150, USA
| | - Wendy L Baxter
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
- The Marmot Society, South Lake Tahoe, CA 96150, USA
| | - George W Koch
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Todd E Dawson
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
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19
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Gessler A. Water transport in trees-the importance of radial and circumferential transport. TREE PHYSIOLOGY 2021; 41:2245-2247. [PMID: 34617110 DOI: 10.1093/treephys/tpab131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 09/01/2021] [Accepted: 09/27/2021] [Indexed: 06/13/2023]
Affiliation(s)
- Arthur Gessler
- Institute of Terrestrial Ecosystems (ITES), Department of Environmental Systems Science, ETH Zurich, Universitaetstrasse 16, 8092 Zurich, Switzerland
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20
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Tomasella M, Casolo V, Natale S, Petruzzellis F, Kofler W, Beikircher B, Mayr S, Nardini A. Shade-induced reduction of stem nonstructural carbohydrates increases xylem vulnerability to embolism and impedes hydraulic recovery in Populus nigra. THE NEW PHYTOLOGIST 2021; 231:108-121. [PMID: 33811346 PMCID: PMC9290559 DOI: 10.1111/nph.17384] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 03/28/2021] [Indexed: 05/08/2023]
Abstract
Nonstructural carbohydrates (NSCs) have been suggested to affect xylem transport under fluctuating water availability, but conclusive evidence is still lacking. We tested the effect of shade-induced NSC depletion on xylem vulnerability to embolism and hydraulic recovery on Populus nigra saplings. Vulnerability was assessed in light-exposed (L) and shaded (S) plants with the hydraulic method, and in vivo with the optical method and X-ray micro-computed tomography. Plants were stressed to 80% loss of hydraulic conductance (PLC) and re-irrigated to check for possible recovery. We measured PLC, bark and wood NSC content, as well as xylem sap pH, surface tension (γsap ) and sugar concentration, before, during and after drought. Shading induced depletion of stem NSC (mainly starch) reserves. All methods converged in indicating higher xylem vulnerability in S than in L plants. This difference was not explained by xylem vessel and pit anatomy or by γsap . Shading impeded sap acidification and sugar accumulation during drought in S plants and prevented hydraulic recovery, which was observed in L plants. Our results highlight the importance of stem NSCs to sustain xylem hydraulic functioning during drought and suggest that light and/or adequate stem NSC thresholds are required to trigger xylem sap chemical changes involved in embolism recovery.
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Affiliation(s)
- Martina Tomasella
- Dipartimento di Scienze della VitaUniversità di TriesteVia L. Giorgieri 10Trieste34127Italy
| | - Valentino Casolo
- Dipartimento di Scienze AgroalimentariAmbientali e AnimaliUniversità di UdineVia delle Scienze 91Udine33100Italy
| | - Sara Natale
- Dipartimento di Scienze della VitaUniversità di TriesteVia L. Giorgieri 10Trieste34127Italy
| | - Francesco Petruzzellis
- Dipartimento di Scienze della VitaUniversità di TriesteVia L. Giorgieri 10Trieste34127Italy
| | - Werner Kofler
- Department of BotanyUniversity of InnsbruckSternwartestraße 15Innsbruck6020Austria
| | - Barbara Beikircher
- Department of BotanyUniversity of InnsbruckSternwartestraße 15Innsbruck6020Austria
| | - Stefan Mayr
- Department of BotanyUniversity of InnsbruckSternwartestraße 15Innsbruck6020Austria
| | - Andrea Nardini
- Dipartimento di Scienze della VitaUniversità di TriesteVia L. Giorgieri 10Trieste34127Italy
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21
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Lombardo F, Gramazio P, Ezura H. Increase in Phloem Area in the Tomato hawaiian skirt Mutant Is Associated with Enhanced Sugar Transport. Genes (Basel) 2021; 12:genes12060932. [PMID: 34207298 PMCID: PMC8234570 DOI: 10.3390/genes12060932] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 06/13/2021] [Accepted: 06/15/2021] [Indexed: 11/29/2022] Open
Abstract
The HAWAIIAN SKIRT (HWS) gene has been described in Arabidopsis, rice, tomato and poplar where it seems to perform distinct functions with relatively little overlap. In tomato, alteration of the gene function confers facultative parthenocarpy, thought to be a consequence of changes in the microRNA metabolism. In the rice mutant, improvement in panicle architecture is associated with an increase in grain yield. Knowing that hws tomato fruits show a higher Brix level, it was suspected that vascular bundles might also be altered in this species, in a similar fashion to the rice phenotype. The pedicel structure of the hws-1 line was therefore examined under the microscope and sugar concentrations from phloem exudate were determined in an enzymatic assay. A distinct increase in the phloem area was observed as well as a higher sugar content in mutant phloem exudates, which is hypothesized to contribute to the high Brix level in the mutant fruits. Furthermore, the described phenotype in this study bridges the gap between Arabidopsis and rice phenotypes, suggesting that the modulation of the microRNA metabolism by HWS influences traits of agricultural interest across several species.
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Affiliation(s)
- Fabien Lombardo
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan;
- Correspondence:
| | - Pietro Gramazio
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan;
| | - Hiroshi Ezura
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan;
- Tsukuba Plant Innovation Research Center, University of Tsukuba, Tsukuba 305-8572, Japan;
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22
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Epron D, Kamakura M, Azuma W, Dannoura M, Kosugi Y. Diurnal variations in the thickness of the inner bark of tree trunks in relation to xylem water potential and phloem turgor. PLANT-ENVIRONMENT INTERACTIONS (HOBOKEN, N.J.) 2021; 2:112-124. [PMID: 37283860 PMCID: PMC10168075 DOI: 10.1002/pei3.10045] [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: 02/10/2021] [Revised: 04/03/2021] [Accepted: 04/07/2021] [Indexed: 06/08/2023]
Abstract
The inner bark plays important roles in tree stems, including radial exchange of water with the xylem and translocation of carbohydrates. Both processes affect the water content and the thickness of the inner bark on a diurnal basis. For the first time, we simultaneously measured the diurnal variations in the inner bark thickness of hinoki cypress (Chamaecyparis obtusa) by using point dendrometers and those of local xylem potential by using stem psychrometers located next to the dendrometers to determine how these variations were related to each other, to phloem turgor and carbohydrate transport. We also estimated the axial hydrostatic pressure gradient by measuring the osmolality of the sap extracted from the inner bark. The inner bark shrunk during the day and swelled during the night with an amplitude related to day-to-day and seasonal variations in climate. The relationship between changes in xylem water potential and inner bark thickness exhibited a hysteresis loop during the day with a median lag of 2 h. A phloem turgor-related signal can be retrieved from the diurnal variations in the inner bark thickness, which was higher at the upper than at the lower position along the trunk. However, a downward hydrostatic pressure gradient was only observed at dawn, suggesting diurnal variations in the phloem sap flow velocity.
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Affiliation(s)
- Daniel Epron
- Graduate School of AgricultureKyoto UniversityKyotoJapan
- AgroParisTechINRAEUMR SILVAUniversité de LorraineNancyFrance
| | - Mai Kamakura
- Graduate School of AgricultureKyoto UniversityKyotoJapan
| | - Wakana Azuma
- Graduate School of Agricultural ScienceKobe UniversityKobeJapan
| | | | - Yoshiko Kosugi
- Graduate School of AgricultureKyoto UniversityKyotoJapan
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23
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Preisler Y, Tatarinov F, Grünzweig JM, Yakir D. Seeking the "point of no return" in the sequence of events leading to mortality of mature trees. PLANT, CELL & ENVIRONMENT 2021; 44:1315-1328. [PMID: 33175417 DOI: 10.1111/pce.13942] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 11/03/2020] [Accepted: 11/08/2020] [Indexed: 06/11/2023]
Abstract
Drought-related tree mortality is increasing globally, but the sequence of events leading to it remains poorly understood. To identify this sequence, we used a 2016 tree mortality event in a semi-arid pine forest where dendrometry and sap flow measurements were carried out in 31 trees, of which seven died. A comparative analysis revealed three stages leading to mortality. First, a decrease in tree diameter in all dying trees, but not in the surviving trees, 8 months "prior to the visual signs of mortality" (PVSM; e.g., near complete canopy browning). Second, a decay to near zero in the diurnal stem swelling/shrinkage dynamics, reflecting the loss of stem radial water flow in the dying trees, 6 months PVSM. Third, cessation of stem sap flow 3 months PVSM. Eventual mortality could therefore be detected long before visual signs were observed, and the three stages identified here demonstrated the differential effects of drought on stem growth, water storage capacity and soil water uptake. The results indicated that breakdown of stem radial water flow and phloem function is a critical element in defining the "point of no return" in the sequence of events leading to mortality of mature trees.
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Affiliation(s)
- Yakir Preisler
- Earth and Planetary Science Department, Weizmann Institute of Science, Rehovot, Israel
- Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Fedor Tatarinov
- Earth and Planetary Science Department, Weizmann Institute of Science, Rehovot, Israel
| | - José M Grünzweig
- Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Dan Yakir
- Earth and Planetary Science Department, Weizmann Institute of Science, Rehovot, Israel
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24
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Comparing Evapotranspiration Estimates from the GEOframe-Prospero Model with Penman–Monteith and Priestley-Taylor Approaches under Different Climate Conditions. WATER 2021. [DOI: 10.3390/w13091221] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Evapotranspiration (ET) is a key variable in the hydrological cycle and it directly impacts the surface balance and its accurate assessment is essential for a correct water management. ET is difficult to measure, since the existing methods for its direct estimate, such as the weighing lysimeter or the eddy-covariance system, are often expensive and require well-trained research personnel. To overcome this limit, different authors developed experimental models for indirect estimation of ET. However, since the accuracy of ET prediction is crucial from different points of view, the continuous search for more and more precise modeling approaches is encouraged. In light of this, the aim of the present work is to test the efficiency in predicting ET fluxes in a newly introduced physical-based model, named Prospero, which is based on the ability to compute the ET using a multi-layer canopy model, solving the energy balance both for the sunlight and shadow vegetation, extending the recently developed Schymanski and Or method to canopy level. Additionally, Prospero is able to compute the actual ET using a Jarvis-like model. The model is integrated as a component in the hydrological modelling system GEOframe. Its estimates were validated against observed data from five Eddy covariance (EC) sites with different climatic conditions and the same vegetation cover. Then, its performances were compared with those of two already consolidated models, the Priestley–Taylor model and Penman FAO model, using four goodness-of-fit indices. Subsequently a calibration of the three methods has been carried out using LUCA calibration within GEOframe, with the purpose of prediction errors. The results showed that Prospero is more accurate and precise with respect to the other two models, even if no calibrations were performed, with better performances in dry climatic conditions. In addition, Prospero model turned to be the least affected by the calibration procedure and, therefore, it can be effectively also used in a context of data scarcity.
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25
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Xiao Z, Chin S, White RG, Gourieroux AM, Pagay V, Tyerman SD, Schmidtke LM, Rogiers SY. Vascular Connections Into the Grape Berry: The Link of Structural Investment to Seededness. FRONTIERS IN PLANT SCIENCE 2021; 12:662433. [PMID: 33936151 PMCID: PMC8083876 DOI: 10.3389/fpls.2021.662433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 03/23/2021] [Indexed: 06/12/2023]
Abstract
Vascular bundles in the grape pedicel and berry contain the conduits, phloem and xylem, for transport of water, sugar, nutrients and signals into and through the grape berry and play a critical role in berry growth and composition. Here, we assess the vascular anatomy within the proximal region of the berry. Guided using a 3D berry model generated by micro-CT, differential staining of transverse sections of berries and receptacles was followed by fluorescent microscopy. Morphometric and vascular characteristics were analyzed within the central proximal region (brush zone, a fibrous extension from the pedicel vascular system into the berry) of the seeded cultivars Shiraz and Sauvignon Blanc, as well as the stenospermocarpic cultivars Ruby Seedless and Flame Seedless. Observations revealed a change in vascular arrangement from the receptacle into the berry brush zone and differences in xylem element size as well as xylem and phloem area relationships. Xylem anatomical and derived hydraulic parameters, as well as total tissue area of xylem and phloem varied between cultivars and in receptacle and berry components. Variation in vascular growth between grape pedicels and berries was independent of seededness. Differences in receptacle xylem vessel size and distribution could contribute to cultivar-dependent xylem backflow constraint.
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Affiliation(s)
- Zeyu Xiao
- Australian Research Council Training Centre for Innovative Wine Production, Adelaide, SA, Australia
- National Wine and Grape Industry Centre, Charles Sturt University, Wagga Wagga, NSW, Australia
| | - Sabrina Chin
- Noble Research Institute LLC, Ardmore, OK, United States
| | - Rosemary G. White
- Commonwealth Scientific and Industrial Research Organisation (CSIRO) Agriculture and Food, Acton, ACT, Australia
| | - Aude M. Gourieroux
- National Wine and Grape Industry Centre, Charles Sturt University, Wagga Wagga, NSW, Australia
| | - Vinay Pagay
- Australian Research Council Training Centre for Innovative Wine Production, Adelaide, SA, Australia
- Department of Wine Science, The University of Adelaide, Glen Osmond, SA, Australia
| | - Stephen D. Tyerman
- Australian Research Council Training Centre for Innovative Wine Production, Adelaide, SA, Australia
- National Wine and Grape Industry Centre, Charles Sturt University, Wagga Wagga, NSW, Australia
- Department of Wine Science, The University of Adelaide, Glen Osmond, SA, Australia
| | - Leigh M. Schmidtke
- Australian Research Council Training Centre for Innovative Wine Production, Adelaide, SA, Australia
- National Wine and Grape Industry Centre, Charles Sturt University, Wagga Wagga, NSW, Australia
| | - Suzy Y. Rogiers
- Australian Research Council Training Centre for Innovative Wine Production, Adelaide, SA, Australia
- National Wine and Grape Industry Centre, Charles Sturt University, Wagga Wagga, NSW, Australia
- New South Wales (NSW) Department of Primary Industries, Wagga Wagga, NSW, Australia
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26
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Mathan J, Singh A, Ranjan A. Sucrose transport in response to drought and salt stress involves ABA-mediated induction of OsSWEET13 and OsSWEET15 in rice. PHYSIOLOGIA PLANTARUM 2021; 171:620-637. [PMID: 32940908 DOI: 10.1111/ppl.13210] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 08/14/2020] [Accepted: 09/07/2020] [Indexed: 05/27/2023]
Abstract
Abiotic stresses, including drought and salinity, negatively affect plant development and physiology at molecular and metabolic levels. Sucrose transport, mediating distribution of photosynthates in plant, is a key physiological process impacted by drought and salinity stresses, as sucrose is a prime energy and signaling molecule as well as an osmolyte. Therefore, understanding the effects of abiotic stresses on sucrose transport and transporters, and underlying genetic and molecular mechanisms, is imperative to maintain sugar homeostasis in plants under stress. Here, we investigated the effects of drought and salinity stresses on sucrose transport and distribution, and on expression levels of genes encoding Sugars Will Eventually be Exported Transporters (SWEETs), along with a potential transcription factor regulating SWEET expression in rice. We observed that drought and salinity stresses increased the sucrose content in leaf and root tissues and in phloem sap of rice indica varieties. Expression analyses of SWEET genes and histochemical analysis of β-glucuronidase-reporter transgenic plants suggested that OsSWEET13 and OsSWEET15 are major SWEET transporters regulating the sucrose transport and levels in response to the abiotic stresses. Transactivation analyses showed that an abscisic acid (ABA)-responsive transcription factor OsbZIP72 directly binds to the promoters of OsSWEET13 and OsSWEET15 and activates their expression. Taken together, the results showed that the higher expressions of OsSWEET13 and OsSWEET15 genes, induced by binding of an ABA-responsive transcription factor OsbZIP72 to the promoters, potentially modulate sucrose transport and distribution in response to the abiotic stresses. The mechanism could possibly be targeted for maintaining sugar homeostasis in rice under drought and salinity stresses.
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Affiliation(s)
| | - Anuradha Singh
- National Institute of Plant Genome Research, New Delhi, India
| | - Aashish Ranjan
- National Institute of Plant Genome Research, New Delhi, India
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Rodríguez-Gamir J, Xue J, Meason DF, Clearwater M, Clinton PW, Domec JC. Interclonal variation, coordination, and trade-offs between hydraulic conductance and gas exchange in Pinus radiata: consequences on plant growth and wood density. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:2419-2433. [PMID: 33337485 DOI: 10.1093/jxb/eraa587] [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: 05/26/2020] [Accepted: 12/17/2020] [Indexed: 05/24/2023]
Abstract
Stem growth reflects genetic and phenotypic differences within a tree species. The plant hydraulic system regulates the carbon economy, and therefore variations in growth and wood density. A whole-organism perspective, by partitioning the hydraulic system, is crucial for understanding the physical and physiological processes that coordinately mediate plant growth. The aim of this study was to determine whether the relationships and trade-offs between (i) hydraulic traits and their relative contribution to the whole-plant hydraulic system, (ii) plant water transport, (iii) CO2 assimilation, (iv) plant growth, and (v) wood density are revealed at the interclonal level within a variable population of 10 Pinus radiata (D. Don) clones for these characters. We demonstrated a strong coordination between several plant organs regarding their hydraulic efficiency. Hydraulic efficiency, gas exchange, and plant growth were intimately linked. Small reductions in stem wood density were related to a large increase in sapwood hydraulic efficiency, and thus to plant growth. However, stem growth rate was negatively related to wood density. We discuss insights explaining the relationships and trade-offs of the plant traits examined in this study. These insights provide a better understanding of the existing coordination, likely to be dependent on genetics, between the biophysical structure of wood, plant growth, hydraulic partitioning, and physiological plant functions in P. radiata.
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Affiliation(s)
- Juan Rodríguez-Gamir
- Producción Vegetal en zonas tropicales y subtropicales, Instituto Canario de Investigaciones Agrarias (ICIA), Ctra de El boquerón s/n, 38270 San Cristóbal de La Laguna, Tenerife, Canary Islands, Spain
- Forest Systems, Scion, Christchurch, New Zealand
| | - Jianming Xue
- Forest Systems, Scion, Christchurch, New Zealand
| | - Dean F Meason
- Forest Systems, Scion, Private Bag 3020, Rotorua, New Zealand
| | - Michael Clearwater
- Environmental Research Institute, University of Waikato, Private Bag 3105, Hamilton, New Zealand
| | | | - Jean-Christophe Domec
- Bordeaux Sciences Agro, UMR INRA ISPA 1391, Gradignan, France
- Nicholas School of the Environment, Duke University, Durham, NC, USA
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van den Herik B, Bergonzi S, Bachem CWB, ten Tusscher K. Modelling the physiological relevance of sucrose export repression by an Flowering Time homolog in the long-distance phloem of potato. PLANT, CELL & ENVIRONMENT 2021; 44:792-806. [PMID: 33314152 PMCID: PMC7986384 DOI: 10.1111/pce.13977] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 12/03/2020] [Accepted: 12/03/2020] [Indexed: 05/31/2023]
Abstract
Yield of harvestable plant organs depends on photosynthetic assimilate production in source leaves, long-distance sucrose transport and sink-strength. While photosynthesis optimization has received considerable interest for optimizing plant yield, the potential for improving long-distance sucrose transport has received far less attention. Interestingly, a recent potato study demonstrates that the tuberigen StSP6A binds to and reduces activity of the StSWEET11 sucrose exporter. While the study suggested that reducing phloem sucrose efflux may enhance tuber yield, the precise mechanism and physiological relevance of this effect remained an open question. Here, we develop the first mechanistic model for sucrose transport, parameterized for potato plants. The model incorporates SWEET-mediated sucrose export, SUT-mediated sucrose retrieval from the apoplast and StSP6A-StSWEET11 interactions. Using this model, we were able to substantiate the physiological relevance of the StSP6A-StSWEET11 interaction in the long-distance phloem for potato tuber yield, as well as to show the non-linear nature of this effect.
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Affiliation(s)
- Bas van den Herik
- Computational Developmental BiologyUtrecht UniversityUtrechtThe Netherlands
| | - Sara Bergonzi
- Plant BreedingWageningen University & ResearchWageningenThe Netherlands
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Sakurai G, Miklavcic SJ. On the Efficacy of Water Transport in Leaves. A Coupled Xylem-Phloem Model of Water and Solute Transport. FRONTIERS IN PLANT SCIENCE 2021; 12:615457. [PMID: 33613602 PMCID: PMC7889512 DOI: 10.3389/fpls.2021.615457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 01/05/2020] [Indexed: 06/12/2023]
Abstract
In this paper, we present and use a coupled xylem/phloem mathematical model of passive water and solute transport through a reticulated vascular system of an angiosperm leaf. We evaluate the effect of leaf width-to-length proportion and orientation of second-order veins on the indexes of water transport into the leaves and sucrose transport from the leaves. We found that the most important factor affecting the steady-state pattern of hydraulic pressure distribution in the xylem and solute concentration in the phloem was leaf shape: narrower/longer leaves are less efficient in convecting xylem water and phloem solutes than wider/shorter leaves under all conditions studied. The degree of efficiency of transport is greatly influenced by the orientation of second-order veins relative to the main vein for all leaf proportions considered; the dependence is non-monotonic with efficiency maximized when the angle is approximately 45° to the main vein, although the angle of peak efficiency depends on other conditions. The sensitivity of transport efficiency to vein orientation increases with increasing vein conductivity. The vein angle at which efficiency is maximum tended to be smaller (relative to the main vein direction) in narrower leaves. The results may help to explain, or at least contribute to our understanding of, the evolution of parallel vein systems in monocot leaves.
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Affiliation(s)
- Gen Sakurai
- Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization, Tsukuba, Japan
| | - Stanley J. Miklavcic
- Phenomics and Bioinformatics Research Centre, University of South Australia, Mawson Lakes, SA, Australia
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Goeschl JD, Han L. A Proposed Drought Response Equation Added to the Münch-Horwitz Theory of Phloem Transport. FRONTIERS IN PLANT SCIENCE 2020; 11:505153. [PMID: 33250905 PMCID: PMC7672028 DOI: 10.3389/fpls.2020.505153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 09/14/2020] [Indexed: 06/12/2023]
Abstract
Theoretical and experimental evidence for an effect of sieve tube turgor pressure on the mechanisms of phloem unloading near the root tips during moderate levels of drought stress is reviewed. An additional, simplified equation is proposed relating decreased turgor pressure to decreased rate kinetics of membrane bound transporters. The effect of such a mechanism would be to decrease phloem transport speed, but increase concentration and pressure, and thus prevent or delay negative pressure in the phloem. Experimental evidence shows this mechanism precedes and exceeds a reduction in stomatal conductance.
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Affiliation(s)
- John D. Goeschl
- Department of Industrial and Systems Engineering, College of Engineering, Texas A&M University, College Station, TX, United States
| | - Lifeng Han
- School of Mathematical and Statistical Sciences, Arizona State University, Tempe, AZ, United States
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Wang Y, Sperry JS, Anderegg WRL, Venturas MD, Trugman AT. A theoretical and empirical assessment of stomatal optimization modeling. THE NEW PHYTOLOGIST 2020; 227:311-325. [PMID: 32248532 DOI: 10.1111/nph.16572] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 03/09/2020] [Indexed: 05/13/2023]
Abstract
Optimal stomatal control models have shown great potential in predicting stomatal behavior and improving carbon cycle modeling. Basic stomatal optimality theory posits that stomatal regulation maximizes the carbon gain relative to a penalty of stomatal opening. All models take a similar approach to calculate instantaneous carbon gain from stomatal opening (the gain function). Where the models diverge is in how they calculate the corresponding penalty (the penalty function). In this review, we compare and evaluate 10 different optimization models in how they quantify the penalty and how well they predict stomatal responses to the environment. We evaluate models in two ways. First, we compare their penalty functions against seven criteria that ensure a unique and qualitatively realistic solution. Second, we quantitatively test model against multiple leaf gas-exchange datasets. The optimization models with better predictive skills have penalty functions that meet our seven criteria and use fitting parameters that are both few in number and physiology based. The most skilled models are those with a penalty function based on stress-induced hydraulic failure. We conclude by proposing a new model that has a hydraulics-based penalty function that meets all seven criteria and demonstrates a highly predictive skill against our test datasets.
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Affiliation(s)
- Yujie Wang
- School of Biological Sciences, University of Utah, Salt Lake City, UT, 84112, USA
| | - John S Sperry
- School of Biological Sciences, University of Utah, Salt Lake City, UT, 84112, USA
| | - William R L Anderegg
- School of Biological Sciences, University of Utah, Salt Lake City, UT, 84112, USA
| | - Martin D Venturas
- School of Biological Sciences, University of Utah, Salt Lake City, UT, 84112, USA
| | - Anna T Trugman
- Department of Geography, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
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32
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Clerx LE, Rockwell FE, Savage JA, Holbrook NM. Ontogenetic scaling of phloem sieve tube anatomy and hydraulic resistance with tree height in Quercus rubra. AMERICAN JOURNAL OF BOTANY 2020; 107:852-863. [PMID: 32468597 DOI: 10.1002/ajb2.1481] [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: 12/24/2019] [Accepted: 03/12/2020] [Indexed: 06/11/2023]
Abstract
PREMISE The dimensions of phloem sieve elements have been shown to vary as a function of tree height, decreasing hydraulic resistance as the transport pathway lengthens. However, little is known about ontogenetic patterns of sieve element scaling. Here we examine within a single species (Quercus rubra) how decreases in hydraulic resistance with distance from the plant apex are mediated by overall plant size. METHODS We sampled and imaged phloem tissue at multiple heights along the main stem and in the live crown of four size classes of trees using fluorescence and scanning electron microscopy. Sieve element length and radius, the number of sieve areas per compound plate, pore number, and pore radius were used to calculate total hydraulic resistance at each sampling location. RESULTS Sieve element length varied with tree size, while sieve element radius, sieve pore radius, and the number of sieve areas per compound plate varied with sampling position. When data from all size classes were aggregated, all four variables followed a power-law trend with distance from the top of the tree. The net effect of these ontogenetic scalings was to make total hydraulic sieve tube resistance independent of tree height from 0.5 to over 20 m. CONCLUSIONS Sieve element development responded to two pieces of information, tree size and distance from the apex, in a manner that conserved total sieve tube resistance across size classes. A further differentiated response between the phloem in the live crown and in the main stem is also suggested.
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Affiliation(s)
- Laura E Clerx
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Fulton E Rockwell
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Jessica A Savage
- Department of Biology, University of Minnesota, Duluth, MN, 55812, USA
| | - N Michele Holbrook
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
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33
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Guo JS, Gear L, Hultine KR, Koch GW, Ogle K. Non-structural carbohydrate dynamics associated with antecedent stem water potential and air temperature in a dominant desert shrub. PLANT, CELL & ENVIRONMENT 2020; 43:1467-1483. [PMID: 32112440 DOI: 10.1111/pce.13749] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 02/14/2020] [Accepted: 02/21/2020] [Indexed: 06/10/2023]
Abstract
Non-structural carbohydrates (NSCs) are necessary for plant growth and affected by plant water status, but the temporal dynamics of water stress impacts on NSC are not well understood. We evaluated how seasonal NSC concentrations varied with plant water status (predawn xylem water potential, Ψ) and air temperature (T) in the evergreen desert shrub Larrea tridentata. Aboveground sugar and starch concentrations were measured weekly or monthly for ~1.5 years on 6-12 shrubs simultaneously instrumented with automated stem psychrometers; leaf photosynthesis (Anet ) was measured monthly for 1 year. Leaf sugar increased during the dry, premonsoon period, associated with lower Ψ (greater water stress) and high T. Leaf sugar accumulation coincided with declines in leaf starch and stem sugar, suggesting the prioritization of leaf sugar during low photosynthetic uptake. Leaf starch was strongly correlated with Anet and peaked during the spring and monsoon seasons, while stem starch remained relatively constant except for depletion during the monsoon. Recent photosynthate appeared sufficient to support spring growth, while monsoon growth required the remobilization of stem starch reserves. The coordinated responses of different NSC fractions to water status, photosynthesis, and growth demands suggest that NSCs serve multiple functions under extreme environmental conditions, including severe drought.
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Affiliation(s)
- Jessica S Guo
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA
| | - Linnea Gear
- Department of Chemistry and Biochemistry, Northern Arizona University, Flagstaff, Arizona, USA
| | - Kevin R Hultine
- Department of Research, Conservation, and Collections, Desert Botanical Garden, Phoenix, Arizona, USA
| | - George W Koch
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA
| | - Kiona Ogle
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, Arizona, USA
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Zhang L, Chen Y, Hao G, Ma K, Bongers F, Sterck FJ. Conifer and broadleaved trees differ in branch allometry but maintain similar functional balances. TREE PHYSIOLOGY 2020; 40:511-519. [PMID: 31976531 DOI: 10.1093/treephys/tpz139] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 11/28/2019] [Accepted: 12/18/2019] [Indexed: 05/29/2023]
Abstract
Conifers and broadleaved trees coexist in temperate forests and are expected to differ in partitioning strategies between leaf and stem. We compare functional balances between water loss and water supply, and between sugar production and sugar transport/storage, and associate these with xylem growth to better understand how they contribute to these life form strategies. We sampled canopy branches from 14 common species in a temperate forest in northeast China and measured xylem area, phloem area, ray area, ray percentage, dry wood density, xylem conductivity and mean xylem growth rate for branch stems, and the leaf area and specific leaf area for leaves, and calculated the leaf-specific conductivity. Conifers and broadleaved trees did not differ significantly in tissue areas, xylem growth rate and the relation between phloem area and leaf area. Conifers had higher xylem area but lower ray area relative to leaf area. For the same xylem conductivity, phloem area and ray parenchyma area did not differ between conifers and broadleaved trees. Xylem growth rate was similar relative to leaf area and phloem area. Our results indicate that conifers tend to develop more xylem area per leaf area and more tracheid area at the cost of ray parenchyma area, probably to compensate for the low water transport ability of tracheid-based xylem. The divergent strategies between conifers and broadleaved tree species in leaf area and xylem area partitioning probably lead to the convergence of partitioning between leaf area and phloem area. Consequently, conifers tend to consume rather than store carbon to achieve a similar xylem expansion per year as coexisting broadleaved trees.
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Affiliation(s)
- Lan Zhang
- Forest Ecology and Forest Management Group, Wageningen University and Research Centre, PO Box 47, Wageningen, 6700 AA, The Netherlands
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, 20 Nanxincun, Xiangshan, Beijing 100093, China
| | - Yajun Chen
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
- Yuanjiang Savanna Ecosystem Research Station, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Pupiao Villiage Yuanjiang, Yunnan 666303, China
| | - Guangyou Hao
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenhe District Shenyang, Liaoning 110016, China
| | - Keping Ma
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, 20 Nanxincun, Xiangshan, Beijing 100093, China
| | - Frans Bongers
- Forest Ecology and Forest Management Group, Wageningen University and Research Centre, PO Box 47, Wageningen, 6700 AA, The Netherlands
| | - Frank J Sterck
- Forest Ecology and Forest Management Group, Wageningen University and Research Centre, PO Box 47, Wageningen, 6700 AA, The Netherlands
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Deng L, Li P, Chu C, Ding Y, Wang S. Symplasmic phloem unloading and post-phloem transport during bamboo internode elongation. TREE PHYSIOLOGY 2020; 40:391-412. [PMID: 31976532 DOI: 10.1093/treephys/tpz140] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Revised: 12/04/2019] [Accepted: 12/18/2019] [Indexed: 05/16/2023]
Abstract
In traditional opinions, no radial transportation was considered to occur in the bamboo internodes but was usually considered to occur in the nodes. Few studies have involved the phloem unloading and post-phloem transport pathways in the rapid elongating bamboo shoots. Our observations indicated a symplastic pathway in phloem unloading and post-unloading pathways in the culms of Fargesiayunnanensis Hsueh et Yi, based on a 5,6-carboxyfluorescein diacetate tracing experiment. Significant lignification and suberinization in fiber and parenchyma cell walls in maturing internodes blocked the apoplastic transport. Assimilates were transported out of the vascular bundles in four directions in the inner zones but in two directions in the outer zones via the continuum of parenchyma cells. In transverse sections, assimilates were outward transported from the inner zones to the outer zones. Assimilates transport velocities varied with time, with the highest values at 0):00 h, which were affected by water transport. The assimilate transport from the adult culms to the young shoots also varied with the developmental degree of bamboo shoots, with the highest transport velocities in the rapidly elongating internodes. The localization of sucrose, glucose, starch grains and the related enzymes reconfirmed that the parenchyma cells in and around the vascular bundles constituted a symplastic pathway for the radial transport of sugars and were the main sites for sugar metabolism. The parenchyma cells functioned as the 'rays' for the radial transport in and between vascular bundles in bamboo internodes. These results systematically revealed the transport mechanism of assimilate and water in the elongating bamboo shoots.
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Affiliation(s)
- Lin Deng
- Key Laboratory for Sympodial Bamboo Research, Southwest Forestry University, Bailong Road, Panlong District, Kunming, Yunnan 650224, P. R. China
| | - Pengcheng Li
- Key Laboratory for Sympodial Bamboo Research, Southwest Forestry University, Bailong Road, Panlong District, Kunming, Yunnan 650224, P. R. China
| | - Caihua Chu
- Key Laboratory for Sympodial Bamboo Research, Southwest Forestry University, Bailong Road, Panlong District, Kunming, Yunnan 650224, P. R. China
| | - Yulong Ding
- Bamboo Research Institute, Nanjing Forestry University, Longpan Road, Xuanwu District, Nanjing, Jiangsu 210037, P.R. China
| | - Shuguang Wang
- Key Laboratory for Sympodial Bamboo Research, Southwest Forestry University, Bailong Road, Panlong District, Kunming, Yunnan 650224, P. R. China
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Salomón RL, De Roo L, Oleksyn J, De Pauw DJW, Steppe K. TReSpire - a biophysical TRee Stem respiration model. THE NEW PHYTOLOGIST 2020; 225:2214-2230. [PMID: 31494939 DOI: 10.1111/nph.16174] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 08/29/2019] [Indexed: 06/10/2023]
Abstract
Mechanistic models of plant respiration remain poorly developed, especially in stems and woody tissues where measurements of CO2 efflux do not necessarily reflect local respiratory activity. We built a process-based model of stem respiration that couples water and carbon fluxes at the organ level (TReSpire). To this end, sap flow, stem diameter variations, xylem and soil water potential, stem temperature, stem CO2 efflux and nonstructural carbohydrates were measured in a maple tree, while xylem CO2 concentration and additional stem and xylem diameter variations were monitored in an ancillary tree for model validation. TReSpire realistically described: (1) turgor pressure to differentiate growing from nongrowing metabolism; (2) maintenance expenditures in xylem and outer tissues based on Arrhenius kinetics and nitrogen content; and (3) radial CO2 diffusivity and CO2 solubility and transport in the sap solution. Collinearity issues with phloem unloading rates and sugar-starch interconversion rates suggest parallel submodelling to close the stem carbon balance. TReSpire brings a breakthrough in the modelling of stem water and carbon fluxes at a detailed (hourly) temporal resolution. TReSpire is calibrated from a sink-driven perspective, and has potential to advance our understanding on stem growth dynamics, CO2 fluxes and underlying respiratory physiology across different species and phenological stages.
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Affiliation(s)
- Roberto L Salomón
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, Ghent, 9000, Belgium
| | - Linus De Roo
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, Ghent, 9000, Belgium
| | - Jacek Oleksyn
- Polish Academy of Sciences, Institute of Dendrology, Parkowa 5, Kórnik, PL-62-035, Poland
| | - Dirk J W De Pauw
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, Ghent, 9000, Belgium
| | - Kathy Steppe
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, Ghent, 9000, Belgium
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El Habti A, Fleury D, Jewell N, Garnett T, Tricker PJ. Tolerance of Combined Drought and Heat Stress Is Associated With Transpiration Maintenance and Water Soluble Carbohydrates in Wheat Grains. FRONTIERS IN PLANT SCIENCE 2020; 11:568693. [PMID: 33178236 PMCID: PMC7593570 DOI: 10.3389/fpls.2020.568693] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 09/22/2020] [Indexed: 05/14/2023]
Abstract
Wheat (Triticum aestivum L.) production is increasingly challenged by simultaneous drought and heatwaves. We assessed the effect of both stresses combined on whole plant water use and carbohydrate partitioning in eight bread wheat genotypes that showed contrasting tolerance. Plant water use was monitored throughout growth, and water-soluble carbohydrates (WSC) and starch were measured following a 3-day heat treatment during drought. Final grain yield was increasingly associated with aboveground biomass and total water use with increasing stress intensity. Combined drought and heat stress immediately reduced daily water use in some genotypes and altered transpiration response to vapor pressure deficit during grain filling, compared to drought only. In grains, glucose and fructose concentrations measured 12 days after anthesis explained 43 and 40% of variation in final grain weight in the main spike, respectively. Starch concentrations in grains offset the reduction in WSC following drought or combined drought and heat stress in some genotypes, while in other genotypes both stresses altered the balance between WSC and starch concentrations. WSC were predominantly allocated to the spike in modern Australian varieties (28-50% of total WSC in the main stem), whereas the stem contained most WSC in older genotypes (67-87%). Drought and combined drought and heat stress increased WSC partitioning to the spike in older genotypes but not in the modern varieties. Ability to maintain transpiration, especially following combined drought and heat stress, appears essential for maintaining wheat productivity.
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Affiliation(s)
- Abdeljalil El Habti
- School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, SA, Australia
- *Correspondence: Abdeljalil El Habti,
| | - Delphine Fleury
- School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, SA, Australia
| | - Nathaniel Jewell
- School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, SA, Australia
- Australian Plant Phenomics Facility, The Plant Accelerator, School of Agriculture, Food & Wine, The University of Adelaide, Adelaide, SA, Australia
| | - Trevor Garnett
- School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, SA, Australia
- Australian Plant Phenomics Facility, The Plant Accelerator, School of Agriculture, Food & Wine, The University of Adelaide, Adelaide, SA, Australia
| | - Penny J. Tricker
- School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, SA, Australia
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Li Q, Wang N, Liu X, Liu S, Wang H, Zhang W, Wang R, Du N. Growth and physiological responses to successional water deficit and recovery in four warm-temperate woody species. PHYSIOLOGIA PLANTARUM 2019; 167:645-660. [PMID: 30637759 DOI: 10.1111/ppl.12922] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 12/20/2018] [Accepted: 01/08/2019] [Indexed: 05/19/2023]
Abstract
Plant responses to drought and their subsequent rehydration can provide evidence for forest dynamics within the context of climate change. In this study, the seedlings of two native species (Vitex negundo var. heterophylla, Quercus acutissima) and two exotic species (Robinia pseudoacacia, Amorpha fruticosa) to China were selected in a greenhouse experiment. The gas exchange, stem hydraulic parameters, plant osmoprotectant contents and antioxidant activities of the seedlings that were subjected to sustained drought and rehydration (test group) as well as those of well-irrigated seedlings (control group) were measured. The two native species exhibited a greater degree of isohydry with drought because they limited the stomatal opening timely from the onset of the drought. However, the two exotic species showed a more 'water spender'-like strategy with R. pseudoacacia showing anisohydric responses and A. fruticosa showing isohydrodynamic responses to drought. Severe drought significantly decreased the leaf gas exchange rates and hydraulic properties, whereas the instantaneous water use efficiency and osmoprotectant contents increased markedly. Most of the physiological parameters recovered rapidly after mild drought rehydration, but the water potential and/or supply of nonstructural carbohydrates did not recover after severe drought rehydration. The results demonstrate that the xylem hydraulic conductivity and shoot water potential jointly play a crucial role in the drought recovery of woody plants. In brief, the native species may play a dominant role in the future in warm-temperate forests because they employ a better balance between carbon gain and water loss than the alien species under extreme drought conditions.
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Affiliation(s)
- Qiang Li
- Institute of Ecology and Biodiversity, School of Life Sciences, Shandong University, Qingdao, 266237, China
- Shandong Provincial Engineering and Technology Research Center for Vegetation Ecology, Shandong University, Qingdao, 266237, China
| | - Ning Wang
- Institute of Ecology and Biodiversity, School of Life Sciences, Shandong University, Qingdao, 266237, China
- Shandong Provincial Engineering and Technology Research Center for Vegetation Ecology, Shandong University, Qingdao, 266237, China
| | - Xiao Liu
- Institute of Ecology and Biodiversity, School of Life Sciences, Shandong University, Qingdao, 266237, China
- Shandong Provincial Engineering and Technology Research Center for Vegetation Ecology, Shandong University, Qingdao, 266237, China
| | - Shuna Liu
- Institute of Ecology and Biodiversity, School of Life Sciences, Shandong University, Qingdao, 266237, China
- Shandong Provincial Engineering and Technology Research Center for Vegetation Ecology, Shandong University, Qingdao, 266237, China
| | - Hui Wang
- Institute of Ecology and Biodiversity, School of Life Sciences, Shandong University, Qingdao, 266237, China
- Shandong Provincial Engineering and Technology Research Center for Vegetation Ecology, Shandong University, Qingdao, 266237, China
| | - Wenxin Zhang
- Institute of Ecology and Biodiversity, School of Life Sciences, Shandong University, Qingdao, 266237, China
- Shandong Provincial Engineering and Technology Research Center for Vegetation Ecology, Shandong University, Qingdao, 266237, China
| | - Renqing Wang
- Institute of Ecology and Biodiversity, School of Life Sciences, Shandong University, Qingdao, 266237, China
- Shandong Provincial Engineering and Technology Research Center for Vegetation Ecology, Shandong University, Qingdao, 266237, China
| | - Ning Du
- Institute of Ecology and Biodiversity, School of Life Sciences, Shandong University, Qingdao, 266237, China
- Shandong Provincial Engineering and Technology Research Center for Vegetation Ecology, Shandong University, Qingdao, 266237, China
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Belhassine F, Martinez S, Bluy S, Fumey D, Kelner JJ, Costes E, Pallas B. Impact of Within-Tree Organ Distances on Floral Induction and Fruit Growth in Apple Tree: Implication of Carbohydrate and Gibberellin Organ Contents. FRONTIERS IN PLANT SCIENCE 2019; 10:1233. [PMID: 31695709 PMCID: PMC6816281 DOI: 10.3389/fpls.2019.01233] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 09/05/2019] [Indexed: 06/10/2023]
Abstract
In plants, organs are inter-dependent for growth and development. Here, we aimed to investigate the distance at which interaction between organs operates and the relative contribution of within-tree variation in carbohydrate and hormonal contents on floral induction and fruit growth, in a fruit tree case study. Manipulations of leaf and fruit numbers were performed in two years on "Golden delicious" apple trees, at the shoot or branch scale or one side of Y-shape trees. For each treatment, floral induction proportion and mean fruit weight were recorded. Gibberellins content in shoot apical meristems, photosynthesis, and non-structural carbohydrate concentrations in organs were measured. Floral induction was promoted by leaf presence and fruit absence but was not associated with non-structural content in meristems. This suggests a combined action of promoting and inhibiting signals originating from leaves and fruit, and involving gibberellins. Nevertheless, these signals act at short distance only since leaf or fruit presence at long distances had no effect on floral induction. Conversely, fruit growth was affected by leaf presence even at long distances when sink demands were imbalanced within the tree, suggesting long distance transport of carbohydrates. We thus clarified the inter-dependence and distance effect among organs, therefore their degree of autonomy that appeared dependent on the process considered, floral induction or fruit growth.
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Affiliation(s)
- Fares Belhassine
- UMR AGAP, Univ. Montpellier, INRA, CIRAD, Montpellier SupAgro, Montpellier, France
- ITK, Montpellier, France
| | - Sébastien Martinez
- UMR AGAP, Univ. Montpellier, INRA, CIRAD, Montpellier SupAgro, Montpellier, France
| | - Sylvie Bluy
- UMR AGAP, Univ. Montpellier, INRA, CIRAD, Montpellier SupAgro, Montpellier, France
| | | | - Jean-Jacques Kelner
- UMR AGAP, Univ. Montpellier, INRA, CIRAD, Montpellier SupAgro, Montpellier, France
| | - Evelyne Costes
- UMR AGAP, Univ. Montpellier, INRA, CIRAD, Montpellier SupAgro, Montpellier, France
| | - Benoît Pallas
- UMR AGAP, Univ. Montpellier, INRA, CIRAD, Montpellier SupAgro, Montpellier, France
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Perri S, Katul GG, Molini A. Xylem-phloem hydraulic coupling explains multiple osmoregulatory responses to salt stress. THE NEW PHYTOLOGIST 2019; 224:644-662. [PMID: 31349369 DOI: 10.1111/nph.16072] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 07/11/2019] [Indexed: 06/10/2023]
Abstract
Salinity is known to affect plant productivity by limiting leaf-level carbon exchange, root water uptake, and carbohydrates transport in the phloem. However, the mechanisms through which plants respond to salt exposure by adjusting leaf gas exchange and xylem-phloem flow are still mostly unexplored. A physically based model coupling xylem, leaf, and phloem flows is here developed to explain different osmoregulation patterns across species. Hydraulic coupling is controlled by leaf water potential, ψl , and determined under four different maximization hypotheses: water uptake (1), carbon assimilation (2), sucrose transport (3), or (4) profit function - i.e. carbon gain minus hydraulic risk. All four hypotheses assume that finite transpiration occurs, providing a further constraint on ψl . With increasing salinity, the model captures different transpiration patterns observed in halophytes (nonmonotonic) and glycophytes (monotonically decreasing) by reproducing the species-specific strength of xylem-leaf-phloem coupling. Salt tolerance thus emerges as plant's capability of differentiating between salt- and drought-induced hydraulic risk, and to regulate internal flows and osmolytes accordingly. Results are shown to be consistent across optimization schemes (1-3) for both halophytes and glycophytes. In halophytes, however, profit-maximization (4) predicts systematically higher ψl than (1-3), pointing to the need of an updated definition of hydraulic cost for halophytes under saline conditions.
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Affiliation(s)
- Saverio Perri
- Masdar Institute, Khalifa University of Science and Technology, PO Box 54224, Abu Dhabi, United Arab Emirates
- Department of Civil Infrastructure and Environmental Engineering, Khalifa University of Science and Technology, PO Box 127788, Abu Dhabi, United Arab Emirates
| | - Gabriel G Katul
- Nicholas School of the Environment, Duke University, Durham, NC, 27710, USA
- Department of Civil and Environmental Engineering, Duke University, Durham, NC, 27708, USA
| | - Annalisa Molini
- Masdar Institute, Khalifa University of Science and Technology, PO Box 54224, Abu Dhabi, United Arab Emirates
- Department of Civil Infrastructure and Environmental Engineering, Khalifa University of Science and Technology, PO Box 127788, Abu Dhabi, United Arab Emirates
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McDowell NG, Brodribb TJ, Nardini A. Hydraulics in the 21 st century. THE NEW PHYTOLOGIST 2019; 224:537-542. [PMID: 31545889 DOI: 10.1111/nph.16151] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Affiliation(s)
| | - Timothy J Brodribb
- School of Biological Science, University of Tasmania, Hobart, TAS, Australia
| | - Andrea Nardini
- Dipartimento di Scienze della Vita, Università di Trieste, Trieste, Italy
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42
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Huber AE, Melcher PJ, Piñeros MA, Setter TL, Bauerle TL. Signal coordination before, during and after stomatal closure in response to drought stress. THE NEW PHYTOLOGIST 2019; 224:675-688. [PMID: 31364171 DOI: 10.1111/nph.16082] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 07/22/2019] [Indexed: 05/27/2023]
Abstract
Signal coordination in response to changes in water availability remains unclear, as does the role of embolism events in signaling drought stress. Sunflowers were exposed to two drought treatments of varying intensity while simultaneously monitoring changes in stomatal conductance, acoustic emissions (AE), turgor pressure, surface-level electrical potential, organ-level water potential and leaf abscisic acid (ABA) concentration. Leaf, stem and root xylem vulnerability to embolism were measured with the single vessel injection technique. In both drought treatments, it was found that AE events and turgor changes preceded the onset of stomatal closure, whereas electrical surface potentials shifted concurrently with stomatal closure. Leaf-level ABA concentration did not change until after stomata were closed. Roots and petioles were equally vulnerable to drought stress based on the single vessel injection technique. However, anatomical analysis of the xylem indicated that the increased AE events were not a result of xylem embolism formation. Additionally, roots and stems never reached a xylem pressure threshold that would initiate runaway embolism throughout the entire experiment. It is concluded that stomatal closure was not embolism-driven, but, rather, that onset of stomatal closure was most closely correlated with the hydraulic signal from changes in leaf turgor.
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Affiliation(s)
- Annika E Huber
- School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, NY, USA
| | - Peter J Melcher
- Biology Department, Center for Natural Sciences, Ithaca College, Ithaca, NY, 14850, NY, USA
| | - Miguel A Piñeros
- School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, NY, USA
- Robert W. Holley Center for Agriculture and Health, USDA-ARS, Cornell University, Ithaca, NY, 14853, NY, USA
| | - Tim L Setter
- School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, NY, USA
| | - Taryn L Bauerle
- School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, NY, USA
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43
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Sevanto S. Methods for Assessing the Role of Phloem Transport in Plant Stress Responses. Methods Mol Biol 2019; 2014:311-336. [PMID: 31197806 DOI: 10.1007/978-1-4939-9562-2_25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Delivery of carbohydrates to tissues that need them under stress is important for plant defenses and survival. Yet, little is known on how phloem function is altered under stress, and how that influences plant responses to stress. This is because phloem is a challenging tissue to study. It consists of cells of various types with soft cell walls, and the cells show strong wounding reactions to protect their integrity, making both imaging and functional studies challenging. This chapter summarizes theories on how phloem transport is affected by stress and presents methods that have been used to gain the current knowledge. These techniques range from tracer studies and imaging to carbon balance and anatomical analyses. Advances in these techniques in the recent years have considerably increased our ability to investigate phloem function, and application of the new methods on plant stress studies will help provide a more comprehensive picture of phloem function and its limitations under stress.
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Affiliation(s)
- Sanna Sevanto
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, USA.
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44
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Smith MR, Merchant A. Limitations to using phloem sap to assess tree water and nutrient status. TREE PHYSIOLOGY 2019; 39:332-339. [PMID: 30551158 DOI: 10.1093/treephys/tpy132] [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: 05/31/2018] [Revised: 11/05/2018] [Accepted: 11/09/2018] [Indexed: 06/09/2023]
Abstract
Rapid, reliable tools are needed to infer physiological and nutritional health for managing forest systems. Understanding the processes governing tree health is central to the development of these tools. Non-foliar approaches such as the collection of phloem sap reflect processes governing both the use and acquisition of plant water and nutrients at a wide range of temporal (diurnal to seasonal) and spatial (canopy) scales. Despite this, phloem sap is not commonly employed due to an incomplete understanding of transport and post-photosynthetic processes and their effects on chemical concentrations and carbon isotope discrimination. We highlight the need to characterize the influences of storage, remobilization and transport on the concentrations of metabolites to address the time and spatial decoupling of phloem contents to that of environmental stimuli. A conceptual framework is suggested to focus research on key phenomena regarding metabolite transport and highlight significant advantages, misconceptions and limitations to its application.
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Affiliation(s)
- Millicent R Smith
- School of Life and Environmental Sciences, Faculty of Science, The University of Sydney, Sydney NSW, Australia
| | - A Merchant
- School of Life and Environmental Sciences, Faculty of Science, The University of Sydney, Sydney NSW, Australia
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45
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Epron D, Dannoura M, Ishida A, Kosugi Y. Estimation of phloem carbon translocation belowground at stand level in a hinoki cypress stand. TREE PHYSIOLOGY 2019; 39:320-331. [PMID: 29474703 DOI: 10.1093/treephys/tpy016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 01/15/2018] [Accepted: 01/27/2018] [Indexed: 06/08/2023]
Abstract
At stand level, carbon translocation in tree stems has to match canopy photosynthesis and carbohydrate requirements to sustain growth and the physiological activities of belowground sinks. This study applied the Hagen-Poiseuille equation to the pressure-flow hypothesis to estimate phloem carbon translocation and evaluate what percentage of canopy photosynthate can be transported belowground in a hinoki cypress (Chamaecyparis obtusa Sieb. et Zucc.) stand. An anatomical study revealed that, in contrast to sieve cell density, conductive phloem thickness and sieve cell hydraulic diameter at 1.3 m in height increased with increasing tree diameter, as did the concentration of soluble sugars in the phloem sap. At tree level, hydraulic conductivity increased by two orders of magnitude from the smallest to the largest trees in the stand, resulting in a stand-level hydraulic conductance of 1.7 × 10-15 m Pa-1 s-1. The osmotic potential of the sap extracted from the inner bark was -0.75 MPa. Assuming that phloem water potential equalled foliage water potential at predawn, the turgor pressure in the phloem at 1.3 m in height was estimated at 0.22 MPa, 0.59 MPa lower than values estimated in the foliage. With this maximal turgor pressure gradient, which would be lower during day-time when foliage water potential drops, the estimated stand-level rate of carbon translocation was 2.0 gC m-2 day-1 (30% of daily gross canopy photosynthesis), at a time of the year when aboveground growth and related respiration is thought to consume a large fraction of photosynthate, at the expense of belowground activity. Despite relying on some assumptions and approximations, this approach, when coupled with measurements of canopy photosynthesis, may further be used to provide qualitative insight into the seasonal dynamics of belowground carbon allocation.
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Affiliation(s)
- Daniel Epron
- Université de Lorraine, INRA, UMR SILVA, Faculté des Sciences et Technologies, Vandœuvre-lès-Nancy, France
- Kyoto University, Laboratory of Ecosystem Production and Dynamics, Graduate School of Global Environmental Studies, Kyoto, Japan
| | - Masako Dannoura
- Kyoto University, Laboratory of Ecosystem Production and Dynamics, Graduate School of Global Environmental Studies, Kyoto, Japan
- Kyoto University, Laboratory of Forest Utilization, Graduate School of Agriculture, Kyoto, Japan
| | - Atsushi Ishida
- Kyoto University, Center for Ecological Research, Otsu, Shiga, Japan
| | - Yoshiko Kosugi
- Kyoto University, Laboratory of Forest Hydrology, Graduate School of Agriculture, Kyoto, Japan
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46
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Stanfield RC, Schulte PJ, Randolph KE, Hacke UG. Computational models evaluating the impact of sieve plates and radial water exchange on phloem pressure gradients. PLANT, CELL & ENVIRONMENT 2019; 42:466-479. [PMID: 30074610 DOI: 10.1111/pce.13414] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 07/20/2018] [Indexed: 05/06/2023]
Abstract
The sugar conducting phloem in angiosperms is a high resistance pathway made up of sieve elements bounded by sieve plates. The high resistance generated by sieve plates may be a trade-off for promoting quick sealing in the event of injury. However, previous modeling efforts have demonstrated a wide variation in the contribution of sieve plates towards total sieve tube resistance. In the current study, we generated high resolution scanning electron microscope images of sieve plates from balsam poplar and integrated them into a mathematical model using Comsol Multiphysics software. We found that sieve plates contribute upwards of 85% towards total sieve tube resistance. Utilizing the Navier-Stokes equations, we found that oblong pores may create over 50% more resistance in comparison with round pores of the same area. Although radial water flows in phloem sieve tubes have been previously considered, their impact on alleviating pressure gradients has not been fully studied. Our novel simulations find that radial water flow can reduce pressure requirements by half in comparison with modeled sieve tubes with no radial permeability. We discuss the implication that sieve tubes may alleviate pressure requirements to overcome high resistances by regulating their membrane permeability along the entire transport pathway.
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Affiliation(s)
- Ryan C Stanfield
- Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada
| | - Paul J Schulte
- School of Life Sciences, University of Nevada-Las Vegas, Las Vegas, Nevada
| | - Katie E Randolph
- School of Life Sciences, University of Nevada-Las Vegas, Las Vegas, Nevada
| | - Uwe G Hacke
- Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada
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47
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Kiorapostolou N, Petit G. Similarities and differences in the balances between leaf, xylem and phloem structures in Fraxinus ornus along an environmental gradient. TREE PHYSIOLOGY 2019; 39:234-242. [PMID: 30189046 DOI: 10.1093/treephys/tpy095] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 07/10/2018] [Accepted: 08/04/2018] [Indexed: 06/08/2023]
Abstract
The plant carbon balance depends on the coordination between photosynthesis and the long-distance transport of water and sugars. How plants modify the allocation to the different structures affecting this coordination under different environmental conditions has been poorly investigated. In this study, we evaluated the effect of soil water availability on the allocation to leaf, xylem and phloem structures in Fraxinus ornus L. We selected small individuals of F. ornus (height ~2 m) from sites contrasting in soil water availability (wet vs dry). We measured how the leaf (LM) and stem + branch biomass (SBM) are cumulated along the stem. Moreover, we assessed the axial variation in xylem (XA) and phloem tissue area (PA), and in lumen area of xylem vessels (CAxy) and phloem sieve elements (CAph). We found a higher ratio of LM:SBM in the trees growing under drier conditions. The long-distance transport tissues of xylem and phloem followed axial patterns with scaling exponents (b) independent of site conditions. PA scaled isometrically with XA (b ~ 1). While CAxy was only marginally higher at the wet sites, CAph was significantly higher at the drier sites. Our results showed that under reduced soil water availability, F. ornus trees allocate relatively more to the leaf biomass and produce more conductive phloem, which is likely to compensate for the drought-related hydraulic limitations to the leaf gas exchanges and the phloem sap viscosity.
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Affiliation(s)
- Natasa Kiorapostolou
- Dipartimento Territorio e Sistemi Agro-Forestali, Università degli studi di Padova, Viale dell'Università 16, Legnaro (PD), Italy
| | - Giai Petit
- Dipartimento Territorio e Sistemi Agro-Forestali, Università degli studi di Padova, Viale dell'Università 16, Legnaro (PD), Italy
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48
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Hesse BD, Goisser M, Hartmann H, Grams TEE. Repeated summer drought delays sugar export from the leaf and impairs phloem transport in mature beech. TREE PHYSIOLOGY 2019; 39:192-200. [PMID: 30388272 DOI: 10.1093/treephys/tpy122] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 09/07/2018] [Accepted: 10/05/2018] [Indexed: 05/24/2023]
Abstract
Phloem sustains maintenance and growth processes through transport of sugars from source to sink organs. Under low water availability, tree functioning is impaired, i.e., growth/photosynthesis decline and phloem transport may be hindered. In a 3-year throughfall exclusion (TE) experiment on mature European beech (Fagus sylvatica L.) we conducted 13CO2 branch labeling to investigate translocation of recently fixed photoassimilates under experimental drought over 2 years (2015 and 2016). We hypothesized (H1) that mean residence time of photoassimilates in leaves (MRT) increases, whereas (H2) phloem transport velocity (Vphloem) decreases under drought. Transport of carbohydrates in the phloem was assessed via δ13C of CO2 efflux measured at two branch positions following 13CO2 labeling. Pre-dawn water potential (ΨPD) and time-integrated soil water deficit (iSWD) were used to quantify drought stress. The MRT increased by 46% from 32.1 ± 5.4 h in control (CO) to 46.9 ± 12.3 h in TE trees, supporting H1, and positively correlated (P < 0.001) with iSWD. Confirming H2, Vphloem in 2016 decreased by 47% from 20.7 ± 5.8 cm h-1 in CO to 11.0 ± 2.9 cm h-1 in TE trees and positively correlated with ΨPD (P = 0.001). We suggest that the positive correlation between MRT and iSWD is a result of the accumulation of osmolytes maintaining cell turgor in the leaves under longer drought periods. Furthermore, we propose that the positive correlation between Vphloem and ΨPD is due to a lower water uptake of phloem conduits from surrounding tissues under increasing drought leading to a higher phloem sap viscosity and lower Vphloem. The two mechanisms increasing MRT and reducing Vphloem respond differently to low water availability and impair trees' carbon translocation under drought.
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Affiliation(s)
- Benjamin D Hesse
- Technical University of Munich, Department of Ecology and Ecosystem Management - Chair for Ecophysiology of Plants, Hans-Carl-von-Carlowitz Platz 2, Freising, Germany
| | - Michael Goisser
- Technical University of Munich, Department of Ecology and Ecosystem Management - Chair for Ecophysiology of Plants, Hans-Carl-von-Carlowitz Platz 2, Freising, Germany
| | - Henrik Hartmann
- Max-Planck Institute for Biogeochemistry, Department of Biogeochemical Processes, Hans Knöll Str. 10, Jena, Germany
| | - Thorsten E E Grams
- Technical University of Munich, Department of Ecology and Ecosystem Management - Chair for Ecophysiology of Plants, Hans-Carl-von-Carlowitz Platz 2, Freising, Germany
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49
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Salmon Y, Dietrich L, Sevanto S, Hölttä T, Dannoura M, Epron D. Drought impacts on tree phloem: from cell-level responses to ecological significance. TREE PHYSIOLOGY 2019; 39:173-191. [PMID: 30726983 DOI: 10.1093/treephys/tpy153] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 12/03/2018] [Accepted: 01/25/2019] [Indexed: 06/09/2023]
Abstract
On-going climate change is increasing the risk of drought stress across large areas worldwide. Such drought events decrease ecosystem productivity and have been increasingly linked to tree mortality. Understanding how trees respond to water shortage is key to predicting the future of ecosystem functions. Phloem is at the core of the tree functions, moving resources such as non-structural carbohydrates, nutrients, and defence and information molecules across the whole plant. Phloem function and ability to transport resources is tightly controlled by the balance of carbon and water fluxes within the tree. As such, drought is expected to impact phloem function by decreasing the amount of available water and new photoassimilates. Yet, the effect of drought on the phloem has received surprisingly little attention in the last decades. Here we review existing knowledge on drought impacts on phloem transport from loading and unloading processes at cellular level to possible effects on long-distance transport and consequences to ecosystems via ecophysiological feedbacks. We also point to new research frontiers that need to be explored to improve our understanding of phloem function under drought. In particular, we show how phloem transport is affected differently by increasing drought intensity, from no response to a slowdown, and explore how severe drought might actually disrupt the phloem transport enough to threaten tree survival. Because transport of resources affects other organisms interacting with the tree, we also review the ecological consequences of phloem response to drought and especially predatory, mutualistic and competitive relations. Finally, as phloem is the main path for carbon from sources to sink, we show how drought can affect biogeochemical cycles through changes in phloem transport. Overall, existing knowledge is consistent with the hypotheses that phloem response to drought matters for understanding tree and ecosystem function. However, future research on a large range of species and ecosystems is urgently needed to gain a comprehensive understanding of the question.
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Affiliation(s)
- Yann Salmon
- Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, Gustaf Hällströmin katu 2b, University of Helsinki, Helsinki, Finland
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, Latokartanonkaari 7, University of Helsinki, Helsinki, Finland
| | - Lars Dietrich
- Department of Environmental Sciences, University of Basel, Schönbeinstrasse 6, Basel, Switzerland
| | - Sanna Sevanto
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, PO Box 1663 MA 495, Los Alamos, NM, USA
| | - Teemu Hölttä
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, Latokartanonkaari 7, University of Helsinki, Helsinki, Finland
| | - Masako Dannoura
- Kyoto University, Laboratory of Ecosystem Production and Dynamics, Graduate School of Global Environmental Studies, Kyoto, Japan
- Kyoto University, Laboratory of Forest Utilization, Graduate School of Agriculture, Kyoto, Japan
| | - Daniel Epron
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
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Dannoura M, Epron D, Desalme D, Massonnet C, Tsuji S, Plain C, Priault P, Gérant D. The impact of prolonged drought on phloem anatomy and phloem transport in young beech trees. TREE PHYSIOLOGY 2019; 39:201-210. [PMID: 29931112 DOI: 10.1093/treephys/tpy070] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 05/04/2018] [Accepted: 05/18/2018] [Indexed: 06/08/2023]
Abstract
Phloem failure has recently been recognized as one of the mechanisms causing tree mortality under drought, though direct evidence is still lacking. We combined 13C pulse-labelling of 8-year-old beech trees (Fagus sylvatica L.) growing outdoors in a nursery with an anatomical study of the phloem tissue in their stems to examine how drought alters carbon transport and phloem transport capacity. For the six trees under drought, predawn leaf water potential ranged from -0.7 to -2.4 MPa, compared with an average of -0.2 MPa in five control trees with no water stress. We also observed a longer residence time of excess 13C in the foliage and the phloem sap in trees under drought compared with controls. Compared with controls, excess 13C in trunk respiration peaked later in trees under moderate drought conditions and showed no decline even after 4 days under more severe drought conditions. We estimated higher phloem sap viscosity in trees under drought. We also observed much smaller sieve-tube radii in all drought-stressed trees, which led to lower sieve-tube conductivity and lower phloem conductance in the tree stem. We concluded that prolonged drought affected phloem transport capacity through a change in anatomy and that the slowdown of phloem transport under drought likely resulted from a reduced driving force due to lower hydrostatic pressure between the source and sink organs.
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Affiliation(s)
- Masako Dannoura
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
- Laboratory of Ecosystem Production and Dynamics, Graduate School of Global Environmental Studies, Kyoto University, Kyoto, Japan
- Laboratory of Forest Utilization, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Daniel Epron
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
| | - Dorine Desalme
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
| | - Catherine Massonnet
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
| | - Shoko Tsuji
- Laboratory of Ecosystem Production and Dynamics, Graduate School of Global Environmental Studies, Kyoto University, Kyoto, Japan
| | - Caroline Plain
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
| | - Pierrick Priault
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
| | - Dominique Gérant
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
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