Positive pressure in xylem and its role in hydraulic function

© 2020 The Authors New Phytologist © 2020 New Phytologist Foundation..

Although transpiration-driven transport of xylem sap is well known to operate under absolute negative pressure, many terrestrial, vascular plants show positive xylem pressure above atmospheric pressure on a seasonal or daily basis, or during early developmental stages. The actual location and mechanisms behind positive xylem pressure remain largely unknown, both in plants that show seasonal xylem pressure before leaf flushing, and those that show a diurnal periodicity of bleeding and guttation. Available evidence shows that positive xylem pressure can be driven based on purely physical forces, osmotic exudation into xylem conduits, or hydraulic pressure in parenchyma cells associated with conduits. The latter two mechanisms may not be mutually exclusive and can be understood based on a similar modelling scenario. Given the renewed interest in positive xylem pressure, this review aims to provide a constructive way forward by discussing similarities and differences of mechanistic models, evaluating available evidence for hydraulic functions, such as rehydration of tissues, refilling of water stores, and embolism repair under positive pressure, and providing recommendations for future research, including methods that avoid or minimise cutting artefacts.

Medienart:

E-Artikel

Erscheinungsjahr:

2021

Erschienen:

2021

Enthalten in:

Zur Gesamtaufnahme - volume:230

Enthalten in:

The New phytologist - 230(2021), 1 vom: 18. Apr., Seite 27-45

Sprache:

Englisch

Beteiligte Personen:

Schenk, H Jochen [VerfasserIn]
Jansen, Steven [VerfasserIn]
Hölttä, Teemu [VerfasserIn]

Links:

Volltext

Themen:

059QF0KO0R
Bleeding
Diurnal pressure
Embolism refilling
Guttation
Journal Article
Rehydration
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Review
Root pressure
Seasonal pressure
Stem pressure
Water

Anmerkungen:

Date Completed 14.05.2021

Date Revised 14.05.2021

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1111/nph.17085

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM317741829