title: Embolism spread in the primary xylem of Polystichum munitum: implications for water transport during seasonal drought.
abstract: Xylem network structure and function have been characterized for many woody plants, but less is known about fern xylem, particularly in species endemic to climates where water is a limiting resource for months at a time. We characterized seasonal variability in soil moisture and frond water status in a common perennial fern in the redwood understory of a costal California, and then investigated the consequences of drought-induced embolism on vascular function. Seasonal variability in air temperature and soil water content was minimal, and frond water potential declined slowly over the observational period. Our data show that Polystichum munitum was protected from significant drought-induced hydraulic dysfunction during this growing season because of a combination of cavitation resistant conduits (Air-seeding threshold (ASP) = -1.53 MPa; xylem pressure inducing 50% loss of hydraulic conductivity (P50 ) = -3.02 MPa) and a soil with low moisture variability. High resolution micro-computed tomography (MicroCT) imaging revealed patterns of embolism formation in vivo for the first time in ferns providing insight into the functional status of the xylem network under drought conditions. Together with stomatal conductance measurements, these data suggest that P. munitum is adapted to tolerate drier conditions than what was observed during the growing season.
authors.affiliation: School of Forestry and Environmental Studies, Yale University, New Haven, CT, 06511, USA.
authors.forename: Craig R
authors.initials: CR
authors.lastname: Brodersen
authors.affiliation: Pioneer Hi-Bred International Inc., Woodland, CA, 95695, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Rico
authors.affiliation: Universidad Central de Venezuela, Facultad de Agronomía, Instituto de Botánica Agrícola, Maracay, 2101, Venezuela.
authors.forename: Orlando
authors.initials: O
authors.lastname: Guenni
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA, 95064, USA.
authors.forename: Jarmila
authors.initials: J
authors.lastname: Pittermann
mesh_terms: D001692:Biological Transport; D055864:Droughts; D006813:Humidity; D054046:Plant Stomata / Q000502:physiology; D032493:Polystichum / Q000502:physiology*; D012621:Seasons; D012987:Soil / Q000737:chemistry; D013696:Temperature; D014867:Water / Q000378:metabolism*; D055114:X-Ray Microtomography; D052584:Xylem / Q000502:physiology*
chemical_list: D012987:Soil; D014867:Water
keywords: Polystichum munitum; air-seeding; cavitation; drought; embolism; fern; microCT; stomatal conductance; xylem