Percolla, Marta , Pratt, R. , Jacobsen, Anna , Tobin, Michael .
Reduced number of vessel connections is positively associated with greater cavitation resistance to water stress in chaparral shrubs.
Within woody plants, xylem tissue carries out numerous functions, including the transport of water, providing mechanical support, and storing resources. Specific functions of the xylem are determined by differences in xylem structure and many previous studies have described some of these important structure-function relationships. An important structural trait of the xylem is the connectedness of vessels within the xylem vessel network (i.e. how many unique vessels a given vessel shares pits with; connectivity); however, the influence of different degrees of connectivity on xylem hydraulic function has not been well established. We hypothesized that a more connected vessel network would be more vulnerable to cavitation because of the presence of more pathways for gas to spread. Moreover, we predicted that greater connectivity would be associated with greater transport efficiency. We measured connectivity, cavitation resistance, and xylem specific hydraulic conductivity for 36 species of chaparral shrubs, half evergreens and half deciduous. Vessel connectivity was quantified as the number of unique vessels sharing cell walls with surrounding vessels in cross section. Lower connectivity was associated with greater levels of cavitation resistance across all species. Xylem specific hydraulic conductivity had a weakly positive association with connectivity for deciduous species, but not evergreens. We conclude that connectivity is an important determinant of cavitation resistance that likely affects the spread of gas through the vessel network via air-seeding. Connectivity is also a likely determining factor of transport efficiency, but other parameters such as vessel density and vessel diameter interact to control maximum efficiency.
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1 - California State University, Department of Biology, 9001 Stockdale Highway, Bakersfield, CA, 93311-1099, USA
2 - CALIFORNIA STATE UNIVERSITY BAKERSFIELD, DEPARTMENT OF BIOLOGY, 9001 Stockdale Highway, Bakersfield, CA, 93311-1099, USA
3 - California State University Bakersfield, 9001 Stockdale Hwy, 61 SCI, Bakersfield, CA, 93311, USA, 310-740-7659
4 - 3910 Tilson Lane, Houston, TX, 77080, USA
Presentation Type: Poster:Posters for Sections
Location: Grand Salon A - D/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 5:45 PM
Candidate for Awards:Physiological Section Best poster presentation,Physiological Section Physiological Section Li-COR Prize