Traugh, C. A. , Pratt, R. B. , Jacobsen, A. L. , Tobin, M.F. , Barrera, S. .
Storage of non-structural carbohydrates in the xylem among chaparral shrub species may come at the cost of reduced stem mechanical strength.
The xylem of angiosperms has three functions: water transport, storage and biomechanical support. Previous research has found trade-offs between water transport and storage with biomechanical traits. In this study, we examined the relationship between biomechanical traits and carbohydrate storage in xylem. We hypothesized a trade-off between biomechanical traits and carbohydrate storage because stronger, denser wood requires increased allocation to fibers which may limit xylem parenchyma volume. This would limit carbohydrate storage because parenchyma are the main cells of the xylem involved in carbohydrate storage. We measured stem xylem biomechanics and carbohydrate storage in ten species of chaparral shrubs located in southern California. We measured the biomechanical traits: modulus of rupture (MOR), which is the maximum amount of stress at the point of fracture in a bending test, and xylem density. To estimate carbohydrate storage, we measured the percentage of total non-structural carbohydrates (TNC) in xylem tissue using an enzymatic method during the fall dry season. Data collected to date suggests a trade-off between MOR and TNC (R=-0.787, p=0.007). The data suggest that the ability of stem xylem to store carbohydrates comes at the cost of reduced mechanical strength among chaparral shrubs.
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1 - California State University Bakersfield, Biology, 9001 Stockdale Hwy, Bakersfield, CA, 93311, USA
2 - California State University, Bakersfield, Biology, 9001 Stockdale Hwy, Bakersfield, CA, 93311, USA
3 - California State University, Bakersfield, Department of Biology, 61 Sci, 9001 Stockdale Hwy, Bakersfield, CA, 93311, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 551B/Convention Center
Date: Monday, August 2nd, 2010
Time: 4:15 PM