title: Increasing atmospheric [CO2] from glacial to future concentrations affects drought tolerance via impacts on leaves, xylem and their integrated function.
abstract: Changes in atmospheric carbon dioxide concentration ([CO2]) affect plant carbon/water tradeoffs, with implications for drought tolerance. Leaf-level studies often indicate that drought tolerance may increase with rising [CO2], but integrated leaf and xylem responses are not well understood in this respect. In addition, the influence of the low [CO2] of the last glacial period on drought tolerance and xylem properties is not well understood. We investigated the interactive effects of a broad range of [CO2] and plant water potentials on leaf function, xylem structure and function and the integration of leaf and xylem function in Phaseolus vulgaris. Elevated [CO2] decreased vessel implosion strength, reduced conduit-specific hydraulic conductance, and compromised leaf-specific xylem hydraulic conductance under moderate drought. By contrast, at glacial [CO2], transpiration was maintained under moderate drought via greater conduit-specific and leaf-specific hydraulic conductance in association with increased vessel implosion strength. Our study involving the integration of leaf and xylem responses suggests that increasing [CO2] does not improve drought tolerance. We show that, under glacial conditions, changes in leaf and xylem properties could increase drought tolerance, while under future conditions, greater productivity may only occur when higher water use can be accommodated.
authors.affiliation: The Holden Arboretum, 9500 Sperry Rd, Kirtland, OH 44094, USA. jsmedeiros42@gmail.com
authors.forename: Juliana S
authors.initials: JS
authors.lastname: Medeiros
authors.forename: Joy K
authors.initials: JK
authors.lastname: Ward
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects*; D000704:Analysis of Variance; D001272:Atmosphere / Q000737:chemistry*; D001692:Biological Transport / Q000187:drug effects; D002245:Carbon Dioxide / Q000494:pharmacology*; D055864:Droughts; D005740:Gases / Q000378:metabolism; D046448:Ice Cover; D008954:Models, Biological; D027805:Phaseolus / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D018515:Plant Leaves / Q000187:drug effects / Q000502:physiology*; D014867:Water / Q000378:metabolism; D052584:Xylem / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology*
chemical_list: D005740:Gases; D014867:Water; D002245:Carbon Dioxide
keywords: drought tolerance; elevated [CO2]; glacial [CO2]; leaf and xylem integration; xylem hydraulic conductance