title: Single vessel air injection estimates of xylem resistance to cavitation are affected by vessel network characteristics and sample length.
abstract: Xylem resistance to cavitation is an important trait that is related to the ecology and survival of plant species. Vessel network characteristics, such as vessel length and connectivity, could affect the spread of emboli from gas-filled vessels to functional ones, triggering their cavitation. We hypothesized that the cavitation resistance of xylem vessels is randomly distributed throughout the vessel network. We predicted that single vessel air injection (SVAI) vulnerability curves (VCs) would thus be affected by sample length. Longer stem samples were predicted to appear more resistant than shorter samples due to the sampled path including greater numbers of vessels. We evaluated the vessel network characteristics of grapevine (Vitis vinifera L.), English oak (Quercus robur L.) and black cottonwood (Populus trichocarpa Torr. & A. Gray), and constructed SVAI VCs for 5- and 20-cm-long segments. We also constructed VCs with a standard centrifuge method and used computer modelling to estimate the curve shift expected for pathways composed of different numbers of vessels. For all three species, the SVAI VCs for 5 cm segments rose exponentially and were more vulnerable than the 20 cm segments. The 5 cm curve shapes were exponential and were consistent with centrifuge VCs. Modelling data supported the observed SVAI VC shifts, which were related to path length and vessel network characteristics. These results suggest that exponential VCs represent the most realistic curve shape for individual vessel resistance distributions for these species. At the network level, the presence of some vessels with a higher resistance to cavitation may help avoid emboli spread during tissue dehydration.
authors.affiliation: Department of Biology, California State University, Bakersfield, 9001 Stockdale Hwy, Bakersfield, CA 93311, USA martin.venturas@gmail.com.|Forest Genetics and Ecophysiology Research Group (GENFOR), School of Forest Engineering, Technical University of Madrid, 28040 Madrid, Spain.
authors.forename: Martin D
authors.initials: MD
authors.lastname: Venturas
authors.affiliation: Department of Biology, California State University, Bakersfield, 9001 Stockdale Hwy, Bakersfield, CA 93311, USA.
authors.forename: F Daniela
authors.initials: FD
authors.lastname: Rodriguez-Zaccaro
authors.affiliation: Department of Biology, California State University, Bakersfield, 9001 Stockdale Hwy, Bakersfield, CA 93311, USA.
authors.forename: Marta I
authors.initials: MI
authors.lastname: Percolla
authors.affiliation: Forestry and Agricultural Biotechnology Institute, University of Pretoria, Lynnwood Road & Roper Street, Hatfield, Pretoria 0002, South Africa.
authors.forename: Casparus J
authors.initials: CJ
authors.lastname: Crous
authors.affiliation: Department of Biology, California State University, Bakersfield, 9001 Stockdale Hwy, Bakersfield, CA 93311, USA.
authors.forename: Anna L
authors.initials: AL
authors.lastname: Jacobsen
authors.affiliation: Department of Biology, California State University, Bakersfield, 9001 Stockdale Hwy, Bakersfield, CA 93311, USA.
authors.forename: R Brandon
authors.initials: RB
authors.lastname: Pratt
mesh_terms: D010935:Plant Diseases; D032107:Populus / Q000502:physiology*; D029963:Quercus / Q000502:physiology*; D027843:Vitis / Q000502:physiology*; D052584:Xylem / Q000502:physiology*
keywords: hydraulic architecture; plant hydraulics; water stress; water transport; xylem anatomy; xylem embolism