Direct observation and modelling of embolism spread between xylem conduits: a case study in Scots pine. (11th November 2016)

• Record Type: Journal Article
• Authors: Torres‐Ruiz, José M.; Cochard, Hervé; Mencuccini, Maurizio; Delzon, Sylvain; Badel, Eric
• Is Part Of: Plant, cell and environment. Volume 39:Number 12(2016)
• Page Start: 2774
• Page End: 2785
• Publication Date: 2016-11-11
• Subjects: cavitation -- fatigue -- vulnerability to embolism -- X‐ray microtomography -- xylem anatomy; Plant physiology -- Periodicals; Plant cells and tissues -- Periodicals; Plant communities -- Periodicals; 581.105
• DOI: 10.1111/pce.12840
• Languages: English
• ISSNs: 0140-7791

Abstract

Abstract: Xylem embolism is one of the main processes involved in drought‐related plant mortality. Although its consequences for plant physiology are already well described, embolism formation and spread are poorly evaluated and modelled, especially for tracheid‐based species. The aim of this study was to assess the embolism formation and spread in Pinus sylvestris as a case study using X‐ray microtomography and hydraulics methods. We also evaluated the potential effects of cavitation fatigue on vulnerability to embolism and the micro‐morphology of the bordered pits using scanning electron microscopy (SEM) to test for possible links between xylem anatomy and embolism spread. Finally, a novel model was developed to simulate the spread of embolism in a 2D anisotropic cellular structure. Results showed a large variability in the formation and spread of embolism within a ring despite no differences being observed in intertracheid pit membrane anatomical traits. Simulations from the model showed a highly anisotropic tracheid‐to‐tracheid embolism spreading pattern, which confirms the major role of tracheid‐to‐tracheid air seeding to explain how embolism spreads in Scots pine. The results also showed that prior embolism removal from the samples reduced the resistance to embolism of the xylem and could result in overestimates of vulnerability to embolism. Abstract : The submitted manuscript addresses, by using X‐ray microtomography and hydraulic methods, a relevant and poorly evaluated question in plant physiology: the embolism formation and spread among xylem conduits in Scots pine as a case study. Results showed a large variability in embolism resistance within a single ring despite no anatomical differences were observed in those traits associated with resistance to embolism between tracheids. Indeed, and for the first time in a tracheid‐based species, an increased vulnerability to embolism was observed in tracheids that were embolized once, confirming the occurrence of cavitation fatigue in conifers. Finally, a novel model was developed to simulate how embolism spreads among tracheids, allowing us to confirm the major role of the tracheid‐to‐tracheid air seeding in the xylem embolism spreading in Scot pine.