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Pteridological Section/AFS

Duckett, Jeffrey G. [1], Ligrone, Roberto [2].

Fungal Endophytes in the Sporophytes and Vascularised Gametophytes of Psilotum and Tmesipteris.

The rhizomes and subterranean gametophytes of Psilotum and Tmesipteris, collected from volcanic tufa and tree ferns respectively in New Zealand, all contain glomeromycotean fungi throughout their parenchymatous cortical cells. Unlike those in some lycophytes the fungi in Psilotum and Tmesipteris are entirely intracellular and closely resemble the Paris- type of arbuscular mycorrhrizas found in seed plants, Botrychium gametophytes and many thalloid hepatics. The fungi are differentiated into large trunk hyphae, arbuscules that undergo several cycles of development and degeneration in the same cell whilst the host cytoplasm remains intact, and massive thin-walled vesicles containing up to 50 nuclei. A further commonality with hepatic glomeromycotes is the presence of numerous bacterial endosymbionts. Following the original description, nearly a century ago, of tracheids in Psilotum gametophytes the same have now been found for the first time in Tmesipteris. In contrast to the well organised steles circumscribed by an endodermis in the rhizomes, the vascular elements in the gametophytes comprise highly elongate parenchyma cells through which are scattered single tracheids and sieve cells, the latter with conspicuous refractive spherules and pores lacking a callose lining. Mitochondrial aggregates, cross-linked by fibrillar elements, previously described from sporophytic tissues in Psilotum and Tmesipteris are also common in the gametophytes of both genera.


1 - Queen Mary, University of London, School of Biological Sciences, London, E1 4NS, UK
2 - Seconda Universita' di Napoli, Facolta' di Scienze Ambientali, via Vivaldi 43, Caserta, I - 81100, Italy

Keywords:
Glomeromycota
mycorrhiza
symbiosis
tracheids
whisk ferns.

Presentation Type: Paper
Session: 22-3
Location: Superior B (Cliff Lodge)
Date: Monday, August 2nd, 2004
Time: 2:30 PM
Abstract ID:435


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