Xylem Structure and the Ascent of Sap

Zimmermann, Martin H.

doi:10.1007/978-3-662-04931-0

Cited by 1,670 publications

(1,563 citation statements)

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“…Linking powered by eXtyles Xylem structural properties have been studied in depth (e.g., Tyree and Zimmermann, 2002) but far less attention has been given to phloem structural requirements. Our study demonstrates that there exist a minimum number of phloem tubes, which is required for the transport of photosynthesized sugars from the leaves.…”

Section: Accepted Manuscript 26mentioning

confidence: 99%

Linking phloem function to structure: Analysis with a coupled xylem–phloem transport model

Hölttä

Mencuccini

Nikinmaa

2009

Journal of Theoretical Biology

196

181

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Cite this article as: T. Hölttä, M. Mencuccini and E. Nikinmaa, Linking phloem function to structure: Analysis with a coupled xylem-phloem transport model, Journal of Theoretical Biology (2009Biology ( ), doi:10.1016Biology ( /j.jtbi.2009 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. We carried out a theoretical analysis of phloem transport based on Münch hypothesis by developing a coupled xylem-phloem transport model. Results showed that the maximum sugar transport rate of the phloem was limited by solution viscosity and that transport requirements were strongly affected by prevailing xylem water potential. The minimum number of xylem and phloem conduits required to sustain transpiration and assimilation, respectively, were calculated. At its maximum sugar transport rate, the phloem functioned with a high turgor pressure difference between the sugar sources and sinks but the turgor pressure difference was reduced if additional parallel conduits were added or solute relays were introduced. Solute relays were shown to decrease the number of parallel sieve tubes needed for phloem transport, leading to a more uniform turgor pressure and allowing faster information transmission within the phloem. Because xylem water potential affected both xylem and phloem transport, the conductance of the two systems was found to be coupled such that large structural investments in the xylem reduced the need for investment in the phloem and vice versa.

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Section: Accepted Manuscript 26mentioning

confidence: 99%

Linking phloem function to structure: Analysis with a coupled xylem–phloem transport model

Hölttä

Mencuccini

Nikinmaa

2009

Journal of Theoretical Biology

196

181

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“…The resulting gas embolisms block water transport in the affected xylem vessel. It is widely accepted that embolisms spread between adjacent conduits when the pressure differential between gas-filled and water-filled conduits reaches a critical point where water vapor is aspirated through the pit membrane from the neighboring conduit (Tyree and Sperry, 1989;Tyree and Zimmermann, 2002). The resulting spread of embolisms through the xylem effectively reduces the hydraulic conductivity of the network, impairing the capacity to replace transpired water.…”

mentioning

confidence: 99%

In Vivo Visualizations of Drought-Induced Embolism Spread in Vitis vinifera

et al. 2013

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Long-distance water transport through plant xylem is vulnerable to hydraulic dysfunction during periods of increased tension on the xylem sap, often coinciding with drought. While the effects of local and systemic embolism on plant water transport and physiology are well documented, the spatial patterns of embolism formation and spread are not well understood. Using a recently developed nondestructive diagnostic imaging tool, high-resolution x-ray computed tomography, we documented the dynamics of drought-induced embolism in grapevine (Vitis vinifera) plants in vivo, producing the first three-dimensional, highresolution, time-lapse observations of embolism spread. Embolisms formed first in the vessels surrounding the pith at stem water potentials of approximately -1.2 megapascals in drought experiments. As stem water potential decreased, embolisms spread radially toward the epidermis within sectored vessel groupings via intervessel connections and conductive xylem relays, and infrequently (16 of 629 total connections) through lateral connections into adjacent vessel sectors. Theoretical loss of conductivity calculated from the high-resolution x-ray computed tomography images showed good agreement with previously published nuclear magnetic resonance imaging and hydraulic conductivity experiments also using grapevine. Overall, these data support a growing body of evidence that xylem organization is critically important to the isolation of drought-induced embolism spread and confirm that air seeding through the pit membranes is the principle mechanism of embolism spread.

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“…Therefore, vessel growth is negatively affected by the water defi cit (Sass & Eckstein, 1995). Since larger vessels in diameter have higher water conducting capacity (Tyree & Zimmermann, 2013), insuffi cient tissue hydration can have negative effect on growth during next vegetation period (Sass & Eckstein, 1995).…”

Section: Lemeur 2004)mentioning

confidence: 99%

Intra-annual radial growth of European beech – a case study in north easternmost stand in Europe

Krišāns

Puriņa

Mesters³

et al. 2016

Forestry Studies

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Abstract. Fagus sylvatica L. is one of the most important commercial tree species in Europe and its natural distribution range is expected to shift northwards due to climatic changes. Detailed information of factors affecting its growth is crucial as a basis for recommendations of wider use of this tree species. Aim of the study was to characterize the changes of radial growth intensity of European beech during a vegetation season. In mature beech stand in northwest Latvia two sample trees (dominant (DT) and suppressed (ST)) were selected in Hylocomiosa forest type. Continuous measurements of changes of stem diameter and xylem sap fl ow as well as meteorological parameters were carried out. Stem cycle approach was applied to distinguish the duration of contraction, expansion and increment of the stem. Onset and cessation of growth of the ST tree was observed several days later compared with DT and mean growth intensity during the entire observation period was considerably lower (0.014 mm/day -1 for ST and 0.022 mm/day -1 for DT, respectively). Most intensive growth increment diurnally was observed in the early morning before sunrise, and seasonally till beginning of July. Positive effect of precipitation and low water pressure defi cit (VPD) on growth was observed, while high VPD coincided with stem contraction. Results indicate the sensitivity of radial growth of European beech to water defi cit and high atmospheric transpirational demand; therefore, future potential of cultivation of beech in Latvia depends on changes in moisture regime.

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Xylem Structure and the Ascent of Sap

Cited by 1,670 publications

References 0 publications

Linking phloem function to structure: Analysis with a coupled xylem–phloem transport model

Linking phloem function to structure: Analysis with a coupled xylem–phloem transport model

In Vivo Visualizations of Drought-Induced Embolism Spread in Vitis vinifera

Intra-annual radial growth of European beech – a case study in north easternmost stand in Europe

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