Research Drought-induced lacuna formation in the stem causes hydraulic conductance to decline before xylem embolism in Selaginella Amanda A. Cardoso1 , Dominik Visel2, Cade N. Kane1, Timothy A. Batz1, Clara Garcıa Sanchez2, Lucian Kaack2, Laurent J. Lamarque3, Yael Wagner4, Andrew King5, Jose M. Torres-Ruiz6 ,Deborah Corso3 ,Regis Burlett3, Eric Badel6, Herve Cochard6 , Sylvain Delzon3 , Steven Jansen2 and Scott A. M. McAdam1 1Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, USA; 2Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, Ulm 89081, Germany; 3INRAE, BIOGECO, University of Bordeaux, Pessac 33615, France; 4Department of Plant & Environmental Sciences, Weizmann Institute of Science, Rehovot 76100, Israel; 5Synchrotron Source Optimisee de Lumiere d’Energie Intermediaire du LURE, L’Orme de Merisiers, Saint Aubin-BP48, Gif-sur-Yvette Cedex, France; 6INRAE, PIAF, Universite Clermont-Auvergne, Clermont-Ferrand 63000, France Summary Author for correspondence: Lycophytes are the earliest diverging extant lineage of vascular plants, sister to all other vas- Scott A. M. McAdam cular plants. Given that most species are adapted to ever-wet environments, it has been Tel: +1 765 494 3650 hypothesized that lycophytes, and by extension the common ancestor of all vascular plants, Email:
[email protected] have few adaptations to drought. Received: 18 March 2020 We investigated the responses to drought of key fitness-related traits such as stomatal reg- Accepted: 22 April 2020 ulation, shoot hydraulic conductance (Kshoot) and stem xylem embolism resistance in Selaginella haematodes and S. pulcherrima, both native to tropical understory. New Phytologist (2020) During drought stomata in both species were found to close before declines in Kshoot, with a : 10.1111/nph.16649 doi 50% loss of Kshoot occurring at À1.7 and À2.5 MPa in S.