University of Oulu

Paljakka T, Rissanen K, Vanhatalo A, Salmon Y, Jyske T, Prisle NL, Linnakoski R, Lin JJ, Laakso T, Kasanen R, Bäck J and Hölttä T (2020) Is Decreased Xylem Sap Surface Tension Associated With Embolism and Loss of Xylem Hydraulic Conductivity in Pathogen-Infected Norway Spruce Saplings? Front. Plant Sci. 11:1090. doi: 10.3389/fpls.2020.01090

Is decreased xylem sap surface tension associated with embolism and loss of xylem hydraulic conductivity in pathogen-infected Norway spruce saplings?

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Author: Paljakka, Teemu1; Rissanen, Kaisa1; Vanhatalo, Anni1;
Organizations: 1Faculty of Agriculture and Forestry, Institute for Atmospheric and Earth System Research/Forest Sciences, University of Helsinki, Helsinki, Finland
2Faculty of Science, Institute for Atmospheric and Earth System Research/Physics, University of Helsinki, Helsinki, Finland
3Natural Resources Institute Finland (Luke), Espoo, Finland
4Nano and Molecular Systems Research Unit, University of Oulu, Oulu, Finland
5Natural Resources Institute Finland (Luke), Helsinki, Finland
6Forest Sciences/Faculty of Agriculture and Forestry, University of Helsinki, Helsinki, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.4 MB)
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Language: English
Published: Frontiers Media, 2020
Publish Date: 2020-08-11


Increased abiotic stress along with increasing temperatures, dry periods and forest disturbances may favor biotic stressors such as simultaneous invasion of bark beetle and ophiostomatoid fungi. It is not fully understood how tree desiccation is associated with colonization of sapwood by fungi. A decrease in xylem sap surface tension (σxylem) as a result of infection has been hypothesized to cause xylem embolism by lowering the threshold for air-seeding at the pits between conduits and disruptions in tree water transport. However, this hypothesis has not yet been tested. We investigated tree water relations by measuring the stem xylem hydraulic conductivity (Kstem), σxylem, stem relative water content (RWCstem), and water potential (Ψstem), and canopy conductance (gcanopy), as well as the compound composition in xylem sap in Norway spruce (Picea abies) saplings. We conducted our measurements at the later stage of Endoconidiophora polonica infection when visible symptoms had occurred in xylem. Saplings of two clones (44 trees altogether) were allocated to treatments of inoculated, wounded control and intact control trees in a greenhouse. The saplings were destructively sampled every second week during summer 2016. σxylem, Kstem and RWCstem decreased following the inoculation, which may indicate that decreased σxylem resulted in increased embolism. gcanopy did not differ between treatments indicating that stomata responded to Ψstem rather than to embolism formation. Concentrations of quinic acid, myo-inositol, sucrose and alkylphenol increased in the xylem sap of inoculated trees. Myo-inositol concentrations also correlated negatively with σxylem and Kstem. Our study is a preliminary investigation of the role of σxylem in E. polonica infected trees based on previous hypotheses. The results suggest that E. polonica infection can lead to a simultaneous decrease in xylem sap surface tension and a decline in tree hydraulic conductivity, thus hampering tree water transport.

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Series: Frontiers in plant science
ISSN: 1664-462X
ISSN-E: 1664-462X
ISSN-L: 1664-462X
Volume: 11
Article number: 1090
DOI: 10.3389/fpls.2020.01090
Type of Publication: A1 Journal article – refereed
Field of Science: 1172 Environmental sciences
114 Physical sciences
Funding: This work was supported by the Academy of Finland grant nos. 324014, 272041, and 305763, the Finnish Cultural Foundation grant no. 00180821, and the Japan Society for the Promotion of Science (JSPS) KAKENHI (grant no. 26·04395). NLP and JJL gratefully acknowledge funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme, Project SURFACE (grant agreement no. 717022), and the Academy of Finland (grant nos. 308238 and 314175).
EU Grant Number: (717022) SURFACE - The unexplored world of aerosol surfaces and their impacts.
Academy of Finland Grant Number: 308238
Detailed Information: 308238 (Academy of Finland Funding decision)
314175 (Academy of Finland Funding decision)
Dataset Reference: The Supplementary Material for this article can be found online at:
Copyright information: © 2020 Paljakka, Rissanen, Vanhatalo, Salmon, Jyske, Prisle, Linnakoski, Lin, Laakso, Kasanen, Bäck and Hölttä. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.