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  1. Article ; Online: Environmental stress and genetics influence night-time leaf conductance in the C

    Christman, Mairgareth A / James, Jeremy J / Drenovsky, Rebecca E / Richards, James H

    Functional plant biology : FPB

    2020  Volume 36, Issue 1, Page(s) 50–55

    Abstract: Growing awareness of night-time leaf conductance ( ... ...

    Abstract Growing awareness of night-time leaf conductance (g
    Language English
    Publishing date 2020-07-21
    Publishing country Australia
    Document type Journal Article
    ZDB-ID 2071582-1
    ISSN 1445-4416 ; 1445-4408
    ISSN (online) 1445-4416
    ISSN 1445-4408
    DOI 10.1071/FP08103
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Single-vessel flow measurements indicate scalariform perforation plates confer higher flow resistance than previously estimated.

    Christman, Mairgareth A / Sperry, John S

    Plant, cell & environment

    2010  Volume 33, Issue 3, Page(s) 431–443

    Abstract: During vessel evolution in angiosperms, scalariform perforation plates with many slit-like openings transformed into simple plates with a single circular opening. The transition is hypothesized to have resulted from selection for decreased hydraulic ... ...

    Abstract During vessel evolution in angiosperms, scalariform perforation plates with many slit-like openings transformed into simple plates with a single circular opening. The transition is hypothesized to have resulted from selection for decreased hydraulic resistance. Previously, additional resistivity of scalariform plates was estimated to be small - generally 10% or less above lumen resistivity - based on numerical and physical models. Here, using the single-vessel technique, we directly measured the hydraulic resistance of individual xylem vessels. The resistivity of simple-plated lumens was not significantly different from the Hagen-Poiseuille (HP) prediction (+6 + or - 3.3% mean deviation). In the 13 scalariform-plated species measured, plate resistivity averaged 99 + or - 13.7% higher than HP lumen resistivity. Scalariform species also showed higher resistivity than simple species at the whole vessel (+340%) and sapwood (+580%) levels. The strongest predictor of scalariform plate resistance was vessel diameter (r(2) = 0.84), followed by plate angle (r(2) = 0.60). An equation based on laminar flow through periodic slits predicted single-vessel measurements reasonably well (r(2) = 0.79) and indicated that Baileyan trends in scalariform plate evolution maintain an approximate balance between lumen and plate resistances. In summary, we found scalariform plates of diverse morphology essentially double lumen flow resistance, impeding xylem flow much more than previously estimated.
    MeSH term(s) Magnoliopsida/anatomy & histology ; Magnoliopsida/physiology ; Models, Theoretical ; Plant Stems/anatomy & histology ; Plant Stems/physiology ; Water/physiology ; Xylem/anatomy & histology ; Xylem/physiology
    Chemical Substances Water (059QF0KO0R)
    Language English
    Publishing date 2010-03
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 391893-2
    ISSN 1365-3040 ; 0140-7791
    ISSN (online) 1365-3040
    ISSN 0140-7791
    DOI 10.1111/j.1365-3040.2009.02094.x
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Rare pits, large vessels and extreme vulnerability to cavitation in a ring-porous tree species.

    Christman, Mairgareth A / Sperry, John S / Smith, Duncan D

    The New phytologist

    2011  Volume 193, Issue 3, Page(s) 713–720

    Abstract: The rare pit hypothesis predicts that the extensive inter-vessel pitting in large early-wood vessels of ring-porous trees should render many of these vessels extremely vulnerable to cavitation by air-seeding. This prediction was tested in Quercus ... ...

    Abstract • The rare pit hypothesis predicts that the extensive inter-vessel pitting in large early-wood vessels of ring-porous trees should render many of these vessels extremely vulnerable to cavitation by air-seeding. This prediction was tested in Quercus gambelii. • Cavitation was assessed from native hydraulic conductivity at field sap tension and in dehydrated branches. Single-vessel air injections gave air-seeding pressures through vessel files; these data were used to estimate air-seeding pressures for inter-vessel walls and pits. • Extensive cavitation occurred at xylem sap tensions below 1 MPa. Refilling occurred below 0.5 MPa and was inhibited by phloem girdling. Remaining vessels cavitated over a wide range to above 4 MPa. Similarly, 40% of injected vessel files air-seeded below 1.0 MPa, whereas the remainder seeded over a wide range exceeding 5 MPa. Inter-vessel walls averaged 1.02 MPa air-seeding pressure, similar and opposite to the mean cavitation tension of 1.22 MPa. Consistent with the rare pit hypothesis, only 7% of inter-vessel pits were estimated to air-seed by 1.22 MPa. • The results confirm the rare pit prediction that a significant fraction of large vessels in Q. gambelii experience high probability of failure by air-seeding.
    MeSH term(s) Air ; Circadian Rhythm ; Dehydration ; Phloem/anatomy & histology ; Phloem/physiology ; Plant Stems/anatomy & histology ; Plant Stems/physiology ; Porosity ; Quercus/anatomy & histology ; Quercus/physiology ; Trees/anatomy & histology ; Trees/physiology ; Water/physiology ; Xylem/anatomy & histology ; Xylem/physiology
    Chemical Substances Water (059QF0KO0R)
    Language English
    Publishing date 2011-12-07
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 208885-x
    ISSN 1469-8137 ; 0028-646X
    ISSN (online) 1469-8137
    ISSN 0028-646X
    DOI 10.1111/j.1469-8137.2011.03984.x
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article: Single-vessel flow measurements indicate scalariform perforation plates confer higher flow resistance than previously estimated

    CHRISTMAN, MAIRGARETH A / SPERRY, JOHN S

    Plant, cell & environment. 2010 Mar., v. 33, no. 3

    2010  

    Abstract: During vessel evolution in angiosperms, scalariform perforation plates with many slit-like openings transformed into simple plates with a single circular opening. The transition is hypothesized to have resulted from selection for decreased hydraulic ... ...

    Abstract During vessel evolution in angiosperms, scalariform perforation plates with many slit-like openings transformed into simple plates with a single circular opening. The transition is hypothesized to have resulted from selection for decreased hydraulic resistance. Previously, additional resistivity of scalariform plates was estimated to be small - generally 10% or less above lumen resistivity - based on numerical and physical models. Here, using the single-vessel technique, we directly measured the hydraulic resistance of individual xylem vessels. The resistivity of simple-plated lumens was not significantly different from the Hagen-Poiseuille (HP) prediction (+6 ± 3.3% mean deviation). In the 13 scalariform-plated species measured, plate resistivity averaged 99 ± 13.7% higher than HP lumen resistivity. Scalariform species also showed higher resistivity than simple species at the whole vessel (+340%) and sapwood (+580%) levels. The strongest predictor of scalariform plate resistance was vessel diameter (r² = 0.84), followed by plate angle (r² = 0.60). An equation based on laminar flow through periodic slits predicted single-vessel measurements reasonably well (r² = 0.79) and indicated that Baileyan trends in scalariform plate evolution maintain an approximate balance between lumen and plate resistances. In summary, we found scalariform plates of diverse morphology essentially double lumen flow resistance, impeding xylem flow much more than previously estimated.
    Keywords hydraulic conductivity
    Language English
    Dates of publication 2010-03
    Size p. 431-443.
    Publisher Blackwell Publishing Ltd
    Publishing place Oxford, UK
    Document type Article
    ZDB-ID 391893-2
    ISSN 1365-3040 ; 0140-7791
    ISSN (online) 1365-3040
    ISSN 0140-7791
    DOI 10.1111/j.1365-3040.2009.02094.x
    Database NAL-Catalogue (AGRICOLA)

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  5. Article ; Online: Testing the 'rare pit' hypothesis for xylem cavitation resistance in three species of Acer.

    Christman, Mairgareth A / Sperry, John S / Adler, Frederick R

    The New phytologist

    2009  Volume 182, Issue 3, Page(s) 664–674

    Abstract: Eudicot angiosperms with greater vulnerability to xylem cavitation tend to have vessels with greater total area of inter-vessel pits, which inspired the 'rare pit' hypothesis: the more pits per vessel, by chance the leakier will be the vessel's single ... ...

    Abstract Eudicot angiosperms with greater vulnerability to xylem cavitation tend to have vessels with greater total area of inter-vessel pits, which inspired the 'rare pit' hypothesis: the more pits per vessel, by chance the leakier will be the vessel's single air-seeding pit and the lower the air-seeding threshold for cavitation to spread between vessels. Here, we demonstrate the feasibility of the hypothesis, using probability theory to model the axial propagation of air through air-injected stems. In the presence of rare, leaky pits, air-seeding pressures through short stems with few vessel ends in series should be low; pressures should increase in longer stems as more end-walls must be breached. Measurements on three Acer species conformed closely to model predictions, confirming the rare presence of leaky pits. The model indicated that pits air-seeding at or below the mean cavitation pressure (MCP) occurred at similarly low frequencies in all species. Average end-wall air-seeding pressures predicted by the model closely matched species' MCPs. Differences in species' vulnerability were primarily attributed to differences in frequency of the leakiest pits rather than pit number or area per vessel. Adjustments in membrane properties and extent of pitting per vessel apparently combine to influence cavitation resistance across species.
    MeSH term(s) Acer/physiology ; Models, Biological ; Plant Stems/anatomy & histology ; Pressure ; Xylem/physiology
    Language English
    Publishing date 2009-05-07
    Publishing country England
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 208885-x
    ISSN 1469-8137 ; 0028-646X
    ISSN (online) 1469-8137
    ISSN 0028-646X
    DOI 10.1111/j.1469-8137.2009.02776.x
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Magnitude of nighttime transpiration does not affect plant growth or nutrition in well-watered Arabidopsis.

    Christman, Mairgareth A / Donovan, Lisa A / Richards, James H

    Physiologia plantarum

    2009  Volume 136, Issue 3, Page(s) 264–273

    Abstract: Significant water loss occurs throughout the night via partially open stomata in many C(3) and C(4) plant species. Although apparently wasteful in terms of water use, nighttime transpiration (E(night)) is hypothesized to benefit plants by enhancing ... ...

    Abstract Significant water loss occurs throughout the night via partially open stomata in many C(3) and C(4) plant species. Although apparently wasteful in terms of water use, nighttime transpiration (E(night)) is hypothesized to benefit plants by enhancing nutrient supply. We tested the hypothesis that plants with greater E(night) would have improved plant nutrient status and greater fitness, estimated as pre-bolting biomass, for Arabidopsis thaliana. Two very different levels of E(night) were generated in plants by exposing them to high vs low nighttime leaf-to-air vapor pressure deficits (VPD(leaf)) in controlled environment chambers. An assessment of responses of nighttime leaf conductance (g(night)) to VPD(leaf) indicated that E(night) differed by at least 80% between the treatments. This large difference in E(night), imposed over the entire vegetative growth phase of Arabidopsis, had no effect on leaf nutrient content (N, Ca, K) or pre-bolting rosette biomass. The lack of response to differences in E(night) held true for both a high and a low nitrogen (N) treatment, even though the low N treatment decreased leaf N and biomass by 40-60%. The N treatment had no effect on g(night). Thus, higher E(night) did not provide a nutrient or growth benefit to Arabidopsis, even when the plants were N-limited.
    MeSH term(s) Arabidopsis/growth & development ; Arabidopsis/metabolism ; Arabidopsis/physiology ; Nitrogen/metabolism ; Photoperiod ; Plant Leaves/growth & development ; Plant Leaves/metabolism ; Plant Leaves/physiology ; Plant Transpiration/physiology ; Water/physiology
    Chemical Substances Water (059QF0KO0R) ; Nitrogen (N762921K75)
    Language English
    Publishing date 2009-07
    Publishing country Denmark
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 2020837-6
    ISSN 1399-3054 ; 0031-9317
    ISSN (online) 1399-3054
    ISSN 0031-9317
    DOI 10.1111/j.1399-3054.2009.01216.x
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Structure-function constraints of tracheid-based xylem: a comparison of conifers and ferns.

    Pittermann, Jarmila / Limm, Emily / Rico, Christopher / Christman, Mairgareth A

    The New phytologist

    2011  Volume 192, Issue 2, Page(s) 449–461

    Abstract: The ferns comprise one of the most ancient tracheophytic plant lineages, and occupy habitats ranging from tundra to deserts and the equatorial tropics. Like their nearest relatives the conifers, modern ferns possess tracheid-based xylem but the structure- ...

    Abstract The ferns comprise one of the most ancient tracheophytic plant lineages, and occupy habitats ranging from tundra to deserts and the equatorial tropics. Like their nearest relatives the conifers, modern ferns possess tracheid-based xylem but the structure-function relationships of fern xylem are poorly understood. Here, we sampled the fronds (megaphylls) of 16 species across the fern phylogeny, and examined the relationships among hydraulic transport, drought-induced cavitation resistance, the xylem anatomy of the stipe, and the gas-exchange response of the pinnae. For comparison, the results are presented alongside a similar suite of conifer data. Fern xylem is as resistant to cavitation as conifer xylem, but exhibits none of the hydraulic or structural trade-offs associated with resistance to cavitation. On a conduit diameter basis, fern xylem can exhibit greater hydraulic efficiency than conifer and angiosperm xylem. In ferns, wide and long tracheids compensate in part for the lack of secondary xylem and allow ferns to exhibit transport rates on a par with those of conifers. We suspect that it is the arrangement of the primary xylem, in addition to the intrinsic traits of the conduits themselves, that may help explain the broad range of cavitation resistance in ferns.
    MeSH term(s) Biological Evolution ; Biological Transport ; Dehydration/genetics ; Dehydration/physiopathology ; Ferns/anatomy & histology ; Ferns/physiology ; Plant Stems/anatomy & histology ; Plant Stems/physiology ; Plant Transpiration ; Structure-Activity Relationship ; Tracheophyta/anatomy & histology ; Tracheophyta/physiology ; Xylem/anatomy & histology ; Xylem/physiology
    Language English
    Publishing date 2011-07-12
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 208885-x
    ISSN 1469-8137 ; 0028-646X
    ISSN (online) 1469-8137
    ISSN 0028-646X
    DOI 10.1111/j.1469-8137.2011.03817.x
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article: Rare pits, large vessels and extreme vulnerability to cavitation in a ring‐porous tree species

    Christman, Mairgareth A / Sperry, John S / Smith, Duncan D

    new phytologist. 2012 Feb., v. 193, no. 3

    2012  

    Abstract: The rare pit hypothesis predicts that the extensive inter‐vessel pitting in large early‐wood vessels of ring‐porous trees should render many of these vessels extremely vulnerable to cavitation by air‐seeding. This prediction was tested in Quercus ... ...

    Abstract • The rare pit hypothesis predicts that the extensive inter‐vessel pitting in large early‐wood vessels of ring‐porous trees should render many of these vessels extremely vulnerable to cavitation by air‐seeding. This prediction was tested in Quercus gambelii. • Cavitation was assessed from native hydraulic conductivity at field sap tension and in dehydrated branches. Single‐vessel air injections gave air‐seeding pressures through vessel files; these data were used to estimate air‐seeding pressures for inter‐vessel walls and pits. • Extensive cavitation occurred at xylem sap tensions below 1 MPa. Refilling occurred below 0.5 MPa and was inhibited by phloem girdling. Remaining vessels cavitated over a wide range to above 4 MPa. Similarly, 40% of injected vessel files air‐seeded below 1.0 MPa, whereas the remainder seeded over a wide range exceeding 5 MPa. Inter‐vessel walls averaged 1.02 MPa air‐seeding pressure, similar and opposite to the mean cavitation tension of 1.22 MPa. Consistent with the rare pit hypothesis, only 7% of inter‐vessel pits were estimated to air‐seed by 1.22 MPa. • The results confirm the rare pit prediction that a significant fraction of large vessels in Q. gambelii experience high probability of failure by air‐seeding.
    Keywords Quercus gambelii ; air ; branches ; girdling ; phloem ; prediction ; probability ; sap ; trees ; xylem
    Language English
    Dates of publication 2012-02
    Size p. 713-720.
    Publishing place Blackwell Publishing Ltd
    Document type Article
    ZDB-ID 208885-x
    ISSN 1469-8137 ; 0028-646X
    ISSN (online) 1469-8137
    ISSN 0028-646X
    DOI 10.1111/j.1469-8137.2011.03984.x
    Database NAL-Catalogue (AGRICOLA)

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  9. Article: Testing hypotheses that link wood anatomy to cavitation resistance and hydraulic conductivity in the genus Acer

    Lens, Frederic / Sperry, John S / Christman, Mairgareth A / Choat, Brendan / Rabaey, David / Jansen, Steven

    New phytologist. 2011 May, v. 190, no. 3

    2011  

    Abstract: Vulnerability to cavitation and conductive efficiency depend on xylem anatomy. We tested a large range of structure-function hypotheses, some for the first time, within a single genus to minimize phylogenetic ‘noise' and maximize detection of ... ...

    Abstract • Vulnerability to cavitation and conductive efficiency depend on xylem anatomy. We tested a large range of structure-function hypotheses, some for the first time, within a single genus to minimize phylogenetic ‘noise' and maximize detection of functionally relevant variation. • This integrative study combined in-depth anatomical observations using light, scanning and transmission electron microscopy of seven Acer taxa, and compared these observations with empirical measures of xylem hydraulics. • Our results reveal a 2 MPa range in species' mean cavitation pressure (MCP). MCP was strongly correlated with intervessel pit structure (membrane thickness and porosity, chamber depth), weakly correlated with pit number per vessel, and not related to pit area per vessel. At the tissue level, there was a strong correlation between MCP and mechanical strength parameters, and some of the first evidence is provided for the functional significance of vessel grouping and thickenings on inner vessel walls. In addition, a strong trade-off was observed between xylem-specific conductivity and MCP. Vessel length and intervessel wall characteristics were implicated in this safety-efficiency trade-off. • Cavitation resistance and hydraulic conductivity in Acer appear to be controlled by a very complex interaction between tissue, vessel network and pit characteristics.
    Keywords Acer ; fluid mechanics ; hydraulic conductivity ; porosity ; scanning electron microscopy ; tree cavities ; wood anatomy ; xylem
    Language English
    Dates of publication 2011-05
    Size p. 709-723.
    Publishing place Blackwell Publishing Ltd
    Document type Article
    ZDB-ID 208885-x
    ISSN 1469-8137 ; 0028-646X
    ISSN (online) 1469-8137
    ISSN 0028-646X
    DOI 10.1111/j.1469-8137.2010.03518.x
    Database NAL-Catalogue (AGRICOLA)

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  10. Article: Structure–function constraints of tracheid‐based xylem: a comparison of conifers and ferns

    Pittermann, Jarmila / Limm, Emily / Rico, Christopher / Christman, Mairgareth A

    new phytologist. 2011 Oct., v. 192, no. 2

    2011  

    Abstract: The ferns comprise one of the most ancient tracheophytic plant lineages, and occupy habitats ranging from tundra to deserts and the equatorial tropics. Like their nearest relatives the conifers, modern ferns possess tracheid‐based xylem but the ... ...

    Abstract • The ferns comprise one of the most ancient tracheophytic plant lineages, and occupy habitats ranging from tundra to deserts and the equatorial tropics. Like their nearest relatives the conifers, modern ferns possess tracheid‐based xylem but the structure–function relationships of fern xylem are poorly understood. • Here, we sampled the fronds (megaphylls) of 16 species across the fern phylogeny, and examined the relationships among hydraulic transport, drought‐induced cavitation resistance, the xylem anatomy of the stipe, and the gas‐exchange response of the pinnae. For comparison, the results are presented alongside a similar suite of conifer data. • Fern xylem is as resistant to cavitation as conifer xylem, but exhibits none of the hydraulic or structural trade‐offs associated with resistance to cavitation. On a conduit diameter basis, fern xylem can exhibit greater hydraulic efficiency than conifer and angiosperm xylem. • In ferns, wide and long tracheids compensate in part for the lack of secondary xylem and allow ferns to exhibit transport rates on a par with those of conifers. We suspect that it is the arrangement of the primary xylem, in addition to the intrinsic traits of the conduits themselves, that may help explain the broad range of cavitation resistance in ferns.
    Keywords Magnoliophyta ; conifers ; deserts ; ferns and fern allies ; habitats ; phylogeny ; secondary xylem ; structure-activity relationships ; tracheids ; tropics ; tundra
    Language English
    Dates of publication 2011-10
    Size p. 449-461.
    Publishing place Blackwell Publishing Ltd
    Document type Article
    ZDB-ID 208885-x
    ISSN 1469-8137 ; 0028-646X
    ISSN (online) 1469-8137
    ISSN 0028-646X
    DOI 10.1111/j.1469-8137.2011.03817.x
    Database NAL-Catalogue (AGRICOLA)

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