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Mayr S, Schmid P, Beikircher B, Feng F, Badel E. Die hard: timberline conifers survive annual winter embolism. New Phytol 2020; 226:13-20. [PMID: 31677276 PMCID: PMC7065000 DOI: 10.1111/nph.16304] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 10/27/2019] [Indexed: 05/02/2023]
Abstract
During winter, timberline trees are exposed to drought and frost, factors known to induce embolism. Studies indicated that conifers cope with winter embolism by xylem refilling. We analysed the loss of hydraulic conductivity (LC) in Picea abies branch xylem over 10 years, and correlated winter embolism to climate parameters. LC was investigated by direct X-ray micro-computer tomography (micro-CT) observations and potential cavitation fatigue by Cavitron measurements. Trees showed up to 100% winter embolism, whereby LC was highest, when climate variables indicated frost drought and likely freeze-thaw stress further increased LC. During summer, LC never exceeded 16%, due to hydraulic recovery. Micro-CT revealed homogenous embolism during winter and that recovery was based on xylem refilling. Summer samples exhibited lower LC in outermost compared to older tree rings, although no cavitation fatigue was detected. Long-term data and micro-CT observations demonstrate that timberline trees can survive annual cycles of pronounced winter-embolism followed by xylem refilling. Only a small portion of the xylem conductivity cannot be restored during the first year, while remaining conduits are refilled without fatigue during consecutive years. We identify important research topics to better understand the complex induction and repair of embolism at the timberline and its relevance to general plant hydraulics.
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Affiliation(s)
- Stefan Mayr
- Department of BotanyUniversity of InnsbruckSternwartestr. 156020InnsbruckAustria
| | - Peter Schmid
- Department of BotanyUniversity of InnsbruckSternwartestr. 156020InnsbruckAustria
| | - Barbara Beikircher
- Department of BotanyUniversity of InnsbruckSternwartestr. 156020InnsbruckAustria
| | - Feng Feng
- College of ForestryNorthwest A&F University3 Taicheng RdYangling712100ShaanxiChina
| | - Eric Badel
- INRA, PIAFUniversité Clermont AuvergneF‐63000Clermont–FerrandFrance
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Holmlund HI, Pratt RB, Jacobsen AL, Davis SD, Pittermann J. High-resolution computed tomography reveals dynamics of desiccation and rehydration in fern petioles of a desiccation-tolerant fern. New Phytol 2019; 224:97-105. [PMID: 31318447 DOI: 10.1111/nph.16067] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 07/11/2019] [Indexed: 06/10/2023]
Abstract
Desiccation-tolerant (DT) plants can dry past -100 MPa and subsequently recover function upon rehydration. Vascular DT plants face the unique challenges of desiccating and rehydrating complex tissues without causing structural damage. However, these dynamics have not been studied in intact DT plants. We used high resolution micro-computed tomography (microCT), light microscopy, and fluorescence microscopy to characterize the dynamics of tissue desiccation and rehydration in petioles (stipes) of intact DT ferns. During desiccation, xylem conduits in stipes embolized before cellular dehydration of living tissues within the vascular cylinder. During resurrection, the chlorenchyma and phloem within the stipe vascular cylinder rehydrated before xylem refilling. We identified unique stipe traits that may facilitate desiccation and resurrection of the vascular system, including xylem conduits containing pectin (which may confer flexibility and wettability); chloroplasts within the vascular cylinder; and an endodermal layer impregnated with hydrophobic substances that impede apoplastic leakage while facilitating the upward flow of water within the vascular cylinder. Resurrection ferns are a novel system for studying extreme dehydration recovery and embolism repair in the petioles of intact plants. The unique anatomical traits identified here may contribute to the spatial and temporal dynamics of water movement observed during desiccation and resurrection.
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Affiliation(s)
- Helen I Holmlund
- University of California, 130 McAllister Way, Santa Cruz, CA, 95060, USA
| | - R Brandon Pratt
- California State University, 9001 Stockdale Hwy, Bakersfield, CA, 93311, USA
| | - Anna L Jacobsen
- California State University, 9001 Stockdale Hwy, Bakersfield, CA, 93311, USA
| | - Stephen D Davis
- Pepperdine University, 24255 Pacific Coast Highway, Malibu, CA, 90263, USA
| | - Jarmila Pittermann
- University of California, 130 McAllister Way, Santa Cruz, CA, 95060, USA
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Affiliation(s)
- Sylvain Delzon
- INRA, University of Bordeaux, UMR BIOGECO, F-33450, Talence, France
| | - Hervé Cochard
- INRA, Clermont University, UMR547 PIAF, F-63100, Clermont-Ferrand, France
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Laur J, Hacke UG. Exploring Picea glauca aquaporins in the context of needle water uptake and xylem refilling. New Phytol 2014; 203:388-400. [PMID: 24702644 DOI: 10.1111/nph.12806] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 03/09/2014] [Indexed: 05/25/2023]
Abstract
Conifer needles have been reported to absorb water under certain conditions. Radial water movement across needle tissues is likely influenced by aquaporin (AQP) water channels. Foliar water uptake and AQP localization in Picea glauca needles were studied using physiological and microscopic methods. AQP expression was measured using quantitative real-time PCR. Members of the AQP gene family in spruce were identified using homology search tools. Needles of drought-stressed plants absorbed water when exposed to high relative humidity (RH). AQPs were present in the endodermis-like bundle sheath, in phloem cells and in the transfusion parenchyma of needles. Up-regulation of AQPs in high RH coincided with embolism repair in stem xylem. The present study also provides the most comprehensive functional and phylogenetic analysis of spruce AQPs to date. Thirty putative complete AQP sequences were found. Our findings are consistent with the hypothesis that AQPs facilitate radial water movement from the needle epidermis towards the vascular tissue. Foliar water uptake may occur in late winter when needles are covered by melting snow and may provide a water source for embolism repair before the beginning of the growing season.
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Affiliation(s)
- Joan Laur
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, AB, T6G 2E3, Canada
| | - Uwe G Hacke
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, AB, T6G 2E3, Canada
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Klein T, Yakir D, Buchmann N, Grünzweig JM. Towards an advanced assessment of the hydrological vulnerability of forests to climate change-induced drought. New Phytol 2014; 201:712-716. [PMID: 24117758 DOI: 10.1111/nph.12548] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Affiliation(s)
- Tamir Klein
- Department of Environmental Sciences and Energy Research, Weizmann Institute of Science, Rehovot, Israel
- Institute of Botany, University of Basel, Basel, Switzerland
| | - Dan Yakir
- Department of Environmental Sciences and Energy Research, Weizmann Institute of Science, Rehovot, Israel
| | - Nina Buchmann
- Institute of Agricultural Sciences, ETH Zürich, Zürich, Switzerland
| | - José M Grünzweig
- Robert H. Smith Faculty of Agriculture, Food and Environment, the Hebrew University of Jerusalem, Rehovot, Israel
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Schneider H, Manz B, Westhoff M, Mimietz S, Szimtenings M, Neuberger T, Faber C, Krohne G, Haase A, Volke F, Zimmermann U. The impact of lipid distribution, composition and mobility on xylem water refilling of the resurrection plant Myrothamnus flabellifolia. New Phytol 2003; 159:487-505. [PMID: 33873352 DOI: 10.1046/j.1469-8137.2003.00814.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
• Lipids play a crucial role in the maintenance of the structural and functional integrity of the water-conducting elements and cells of the resurrection plant Myrothamnus flabellifolia during complete dehydration. • Lipid composition, mobility and distribution within the internodal and nodal xylem regions (including short shoots and leaves) were investigated in the presence and absence of water by using various nuclear magnetic resonance (NMR) spectroscopy and imaging techniques differing greatly in the level of spatial resolution and acquisition of lipid parameters. • Significant findings include: a discontinuity in the branch xylem between an inner zone where no water moves and an outer zone where the water moves; the blocking of water movement in the inner zone by lipids that are not dispersed by water, and the facilitation of water advance in the xylem elements and pits of the outer zone by water-dispersed lipids; the relative impermeability of leaf trace xylem to the rehydrating water and, hence, the relative hydraulic isolation of the leaves. • These results elucidated part of the strategy used by the resurrection plant to cope with extreme drought and to minimize transpirational water loss upon hydration.
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Affiliation(s)
- H Schneider
- Lehrstuhl für Biotechnologie, Biozentrum der Universität, Am Hubland, D-97074 Würzburg, Germany
| | - B Manz
- Fraunhofer Institut für Biomedizinische Technik, Ensheimer Strasse 48, D-66386 St Ingbert, Germany
| | - M Westhoff
- Lehrstuhl für Biotechnologie, Biozentrum der Universität, Am Hubland, D-97074 Würzburg, Germany
| | - S Mimietz
- Lehrstuhl für Biotechnologie, Biozentrum der Universität, Am Hubland, D-97074 Würzburg, Germany
| | - M Szimtenings
- Lehrstuhl für Experimentelle Physik V (Biophysik) der Universität, Am Hubland, D-97074 Würzburg, Germany
| | - T Neuberger
- Lehrstuhl für Experimentelle Physik V (Biophysik) der Universität, Am Hubland, D-97074 Würzburg, Germany
| | - C Faber
- Lehrstuhl für Experimentelle Physik V (Biophysik) der Universität, Am Hubland, D-97074 Würzburg, Germany
| | - G Krohne
- Abteilung für Elektronenmikroskopie, Biozentrum der Universität, Am Hubland, D-97074 Würzburg, Germany
| | - A Haase
- Lehrstuhl für Experimentelle Physik V (Biophysik) der Universität, Am Hubland, D-97074 Würzburg, Germany
| | - F Volke
- Fraunhofer Institut für Biomedizinische Technik, Ensheimer Strasse 48, D-66386 St Ingbert, Germany
| | - U Zimmermann
- Lehrstuhl für Biotechnologie, Biozentrum der Universität, Am Hubland, D-97074 Würzburg, Germany
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