Alpine dwarf shrubs show high proportions of nonfunctional xylem: Visualization and quantification of species‐specific patterns. (1st December 2021)

• Record Type: Journal Article
• Authors: Ganthaler, Andrea; Bär, Andreas; Dämon, Birgit; Losso, Adriano; Nardini, Andrea; Dullin, Christian; Tromba, Giuliana; von Arx, Georg; Mayr, Stefan
• Is Part Of: Plant, cell and environment. Volume 45:Number 1(2022)
• Page Start: 55
• Page End: 68
• Publication Date: 2021-12-01
• Subjects: embolism -- Ericaceae -- growth form -- hydraulic conductivity -- hydraulic dysfunction -- micro‐CT -- nondestructive imaging -- water transport -- woody plants -- xylem anatomy; Plant physiology -- Periodicals; Plant cells and tissues -- Periodicals; Plant communities -- Periodicals; 581.105
• DOI: 10.1111/pce.14226
• Languages: English
• ISSNs: 0140-7791

Abstract

Abstract: Xylem conductive capacity is a key determinant of plant hydraulic function and intimately linked to photosynthesis and productivity, but can be impeded by temporary or permanent conduit dysfunctions. Here we show that persistent xylem dysfunctions in unstressed plants are frequent in Alpine dwarf shrubs and occur in various but species‐specific cross‐sectional patterns. Combined synchrotron micro‐computed tomography (micro‐CT) imaging, xylem staining, and flow measurements in saturated samples of six widespread Ericaceae species evidence a high proportion (19%–50%) of hydraulically nonfunctional xylem areas in the absence of drought stress, with regular distribution of dysfunctions between or within growth rings. Dysfunctions were only partly reversible and reduced the specific hydraulic conductivity to 1.38 to 3.57 ×10 −4 m 2 s −1 MPa −1 . Decommission of inner growth rings was clearly related to stem age and a higher vulnerability to cavitation of older rings, while the high proportion of nonfunctional conduits in each annual ring needs further investigations. The lower the xylem fraction contributing to the transport function, the higher was the hydraulic efficiency of conducting xylem areas. Improved understanding of the functional lifespan of xylem elements and the prevalence and nature of dysfunctions is critical to correctly assess structure‐function relationships and whole‐plant hydraulic strategies. Abstract : Alpine dwarf shrubs exhibit a high proportion of hydraulically non‐functional xylem conduits in the absence of drought stress, with species‐specific cross‐sectional distribution patterns. Dysfunctions are partly reversible and considerably reduce the hydraulic conductivity.