Drought-induced lacuna formation in the stem causes hydraulic conductance to decline before xylem embolism in Selaginella
Cardoso, Amanda, A | Visel, Dominik | Kane, Cade, N. | Batz, Timothy | Garcia Sànchez, Clara | Kaack, Lucian | Lamarque, Laurent | Wagner, Yael | King, Andrew | Torres Ruiz, Jose Manuel | Corso, Déborath | Burlett, Regis | Badel, Eric | Cochard, Hervé | Delzon, Sylvain | Jansen, Steven | Mcadam, Scott A. M. | Department of Statistics (Purdue University) ; Purdue University [West Lafayette] | Universität Ulm - Ulm University [Ulm, Allemagne] | Perdue University | Biodiversité, Gènes & Communautés (BioGeCo) ; Université de Bordeaux (UB)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) | Weizmann Institute of Science [Rehovot, Israël] | Synchrotron SOLEIL (SSOLEIL) ; Centre National de la Recherche Scientifique (CNRS) | Laboratoire de Physique et Physiologie Intégratives de l’Arbre en environnement Fluctuant (PIAF) ; Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) | Federation of European Societies of Plant Biology New Phytologist Trust
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Показать больше [+] Меньше [-]Английский. Lycophytes are the earliest diverging extant lineage of vascular plants, sister to all other vas-cular plants. Given that most species are adapted to ever-wet environments, it has been hypothesized that lycophytes, and by extension the common ancestor of all vascular plants, have few adaptations to drought. We investigated the responses to drought of key fitness-related traits such as stomatal regulation , shoot hydraulic conductance (K shoot) and stem xylem embolism resistance in Selaginella haematodes and S. pulcherrima, both native to tropical understory. During drought stomata in both species were found to close before declines in K shoot , with a 50% loss of K shoot occurring at À1.7 and À2.5 MPa in S. haematodes and S. pulcherrima, respectively. Direct observational methods revealed that the xylem of both species was resistant to embolism formation, with 50% of embolized xylem area occurring at À3.0 and À4.6 MPa in S. haematodes and S. pulcherrima, respectively. X-ray microcomputed tomogra-phy images of stems revealed that the decline in K shoot occurred with the formation of an air-filled lacuna, disconnecting the central vascular cylinder from the cortex. We propose that embolism-resistant xylem and large capacitance, provided by collapsing inner cortical cells, is essential for Selaginella survival during water deficit.
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