Developmental and Structural Section
Montes, Monica , Bobich, Edward , Ewers, Frank .
Development and function of gelatinous fibers in response to mechanical stress in stems of Ephedra aspera and Ephedra viridis.
Gelatinous fibers (g-fibers) are usually associated with reaction wood in angiosperms; particularly in tension wood, which forms in response to gravitational stresses. In g-fibers, the innermost layer of the secondary cell wall is rich in cellulose and poor in lignin and likely functions in reorienting organs. G-fibers are also found in the three genera of what is traditionally known as the Gnetales (Ephedra, Gnetum, and Welwitschia), which is interesting because that lineage has been placed within the conifers, which lack g-fibers, or as sister to the angiosperms, the only other group known to have g-fibers. In species of Ephedra,which are native to arid and semiarid regions throughout the world, g-fibers occur primarily in the cortex and pith. Based on previous research for Gnetum, it was hypothesized that the shrubby Ephedra aspera and E. viridis would produce g-fibers as a response to mechanical stress (i.e. bending). Total number of g-fibers did not differ between bent and unbent stems of either species of Ephedra, and the oldest stems studied had the lowest g-fiber frequency indicating that little to no new g-fibers were produced as the stems aged. Furthermore there were no other indications of reaction anatomy for E.aspera or E. viridis. The results call in to question the actual function of g-fibers in Ephedra, especially shrubby species.
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1 - California State Polytechnic University, Pomona, Biological Sciences, 3801 W. Temple Ave, Pomona, CA, 91768, USA
2 - California State Polytechnic University, Pomona, Office Of Research, 3801 West Temple Avenue, Pomona, CA, 91768, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Union D/Hyatt
Date: Tuesday, July 10th, 2012
Time: 3:00 PM