Abstract Detail

Paleobotany

Foster, Madison [1], Harper, Carla [2], Krings, Michael [3].

Unraveling the diversity of mycelial cords from the Lower Devonian Rhynie chert.

The Rhynie chert, a silicified Early Devonian hot spring ecosystem in Aberdeenshire, Scotland, is one of the most important sources of new information on the diversity of early non-marine fungi and the roles these organisms played in early continental ecosystems. The scientifically most relevant, and hence most intensively studied fungal fossils from the Rhynie chert are the arbuscular mycorrhizas formed by members of the Mucoromycota (Glomeromycotina and Mucoromycotina) with several of the Rhynie chert land plants. One highly interesting but to date understudied feature of the Rhynie chert mycorrhizal fungi is their ability to form mycelial cords, i.e. bundles of linearly aligned hyphae that function in long distance transport, but can also facilitate the uptake of water or nutrients by the host plant under stressful conditions. We here present a first assessment and categorization of mycelial cord morphology from the Rhynie chert based on >50 thin section preparations containing >100 specimens of cords. The cords are constructed of 4 to >20 hyphae, which are sparsely septate and 10–50 µm in diameter. Cords in surface view show a variety of different features such as single to multiple Y-branches, H-branches, and right-angled branches, as well as complex interweaving of hyphae and hyphal knots. In addition, some of the hyphae produce globose to ellipsoidal vesicles ~50 µm in diameter. Cords usually occur singly, but two or more cords extending parallel have also been found. Transverse sections show that larger cords (>15 hyphae) usually consist of a single central, thick-walled hypha that is surrounded by several smaller-diameter, thin-walled hyphae. Intrahyphal hyphae are common in cord hyphae. The data gathered to date enable the proposal of a categorization scheme for Rhynie chert mycelial cords in surface view based on branching patterns. As the first study specifically addressing mycelial cords in the Rhynie chert, this research is significant because it increases our knowledge of the morphology, biology, and possibly interactions with plants and the surrounding soil matrix of Early Devonian mycorrhizal fungi.

1 - University of Kansas, Ecology and Evolutionary Biology , 1200 Sunnyside Ave, Lawrence , KS, 66045, USA
2 - University Of Kansas, Ecology And Evolutionary Biology, 1200 Sunnyside Ave, Haworth Hall, Lawrence, KS, 66045, United States
3 - Bayerische Staatssammlung Für Paläontologie Und Ge, Richard-Wagner Strasse 10, Munich, D-80333, Germany

Keywords:
fossil fungi
glomeromycota
plant-fungus interaction
Devonian
categorization.

Presentation Type: Oral Paper
Session: 28, Cookson Award Session I
Location: 109/Mayo Civic Center
Date: Tuesday, July 24th, 2018
Time: 1:30 PM
Number: 28001
Abstract ID:231
Candidate for Awards:Isabel Cookson Award,Maynard F. Moseley Award