AOBPreview originally published online on August 25, 2006
Annals of Botany 2006 98(5):943-951; doi:10.1093/aob/mcl183
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The Micromorphology of Pit Membranes in Tracheary Elements of Ericales: New Records of Tori or Pseudo-tori?
1 Laboratory of Plant Systematics, K.U.Leuven, Institute of Botany and Microbiology Kasteelpark Arenberg 31, B-3001 Heverlee, Belgium
2 National Herbarium of the Netherlands, Leiden University Branch PO Box 9514, NL-2300 RA Leiden, The Netherlands
3 Jodrell Laboratory, Royal Botanic Gardens Kew, Richmond, Surrey TW9 3DS, UK
* For correspondence: E-mail s.jansen{at}rbgkew.org.uk
Received: 17 March 2006 Returned for revision: 14 June 2006 Accepted: 5 July 2006 Published electronically: 25 August 2006
Background and Aims Intervascular pit membranes were examined within Ericales to determine the distribution and structure of torus-like thickenings.
Methods Forty-nine species representing 12 families of the order Ericales were investigated using light, scanning and transmission electron microscopy. They were compared with four species of Oleaceae to determine the true nature of the thickenings.
Key Results Pit membranes with torus-like thickenings were observed in seven species of Ericaceae and were found to be amorphous, plasmodesmata-associated structures with an irregular distribution. These pseudo-tori show major differences compared with true tori with respect to their distribution and ultrastructure. Genuine tori, which are strongly correlated with round pit apertures in narrow tracheary elements, were found in two species of Osmanthus (Oleaceae).
Conclusions The pseudo-tori found in some Ericaceae are considered to be similar to pit membrane thickenings previously recorded in Rosaceae. While true tori appear to be functionally significant in terms of efficiency and safety of water transport, the possible function of pseudo-tori could be associated with the role of plasmodesmata during differentiation of tracheids, fibre-tracheids or narrow vessels.
Key words: Ericaceae, Ericales, Oleaceae, pit membrane, plasmodesmata, pseudo-torus, torus, tracheary elements
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S. Jansen, Y. Sano, B. Choat, D. Rabaey, F. Lens, and R. R. Dute Pit membranes in tracheary elements of Rosaceae and related families: new records of tori and pseudotori Am. J. Botany, April 1, 2007; 94(4): 503 - 514. [Abstract] [Full Text] [PDF] |
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