PIT MEMBRANES OF EPHEDRA RESEMBLE GYMNOSPERMS MORE THAN ANGIOSPERMS

In: IAWA Journal
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  • 1 Department of Biological Sciences, Auburn University, Life Sciences Building, Auburn, Alabama 36849-5407, U.S.A.
  • | 2 Department of Biological Sciences, Auburn University, Life Sciences Building, Auburn, Alabama 36849-5407, U.S.A.
  • | 3 Department of Biological Sciences, Auburn University, Life Sciences Building, Auburn, Alabama 36849-5407, U.S.A.
  • | 4 Department of Biological Sciences, Auburn University, Life Sciences Building, Auburn, Alabama 36849-5407, U.S.A.
  • | 5 Department of Biological Sciences, Auburn University, Life Sciences Building, Auburn, Alabama 36849-5407, U.S.A.
  • | 6 Department of Polymer and Fiber Engineering, Auburn University, Auburn, Alabama,U.S.A.
  • | 7 USDA-Forest Service, Southern Research Station, 2500 Shreveport Highway, Pineville, Louisiana 71360, U.S.A.
  • | 8 Institute for Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, D-89081, Ulm, Germany
  • | 9 UMR BIOGECO, INRA, University of Bordeaux, Avenue des Facultés Bat. B2, 33405 Talence, France
  • | 10 Institute for Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, D-89081, Ulm, Germany

Bordered pit pairs of Ephedra species were characterized using different types of microscopy. Pit membranes contained tori that did not stain for lignin. SEM and AFM views of the torus surface showed no plasmodesmatal openings, but branched, secondary plasmodesmata were occasionally noted using TEM in conjunction with ultrathin sections. The margo consisted of radial microfibrils as well as finer diameter tangential fibrils. The former formed fascicles of fibrils that merged into even thicker buttresses during the act of pit membrane aspiration. AFM showed a discontinuous layer of non-microfibrillar material on the surface of both torus and margo. It is hypothesized that this material is responsible for adhesion of the pit membrane to the surface of the pit border during the process of aspiration. Taken as a whole, intervascular pit membranes of Ephedra more closely resemble those of conifers than those of torus-bearing pit membranes of angiosperms.

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