Mycorrhizal root nodules in a Triassic conifer
Some 80% of land plants today enter into mutually beneficial partnerships with certain root-inhabiting fungi (mycorrhizae), in which the fungus delivers nutrients to the plant and receives a carbon reward. Some plants, including the conifer families Araucariaceae, Podocarpaceae, and Sciadopityaceae, have evolved specific structures termed mycorrhizal root nodules to house the fungus. Although the fossil record of these conifer families can be traced back into the early Mesozoic, the oldest fossil evidence of root nodules previously came from the Cretaceous. A recent study in the prestigious journal PNAS, authored by scientists of the University of Kansas (USA) and Michael Krings, reports on cellularly preserved mycorrhizal root nodules that occur in a conifer from the Middle Triassic of Antarctica. These fossil root nodules contain fungi that form a symbiotic association with the plant. Numerous fungal spores very similar to those of present-day mycorrhizal fungi are found in the peat matrix surrounding the nodules. This discovery indicates that mutualistic associations between conifer root nodules and mycorrhizal fungi date back to at least the early Mesozoic, the period during which most of the modern conifer families first appeared. The root nodules from Antarctica predate the next known appearance of this association by 100 million years, indicating that this specialized form of mycorrhizal symbiosis has ancient origins.
"Morphological and functional stasis in mycorrhizal root nodules as exhibited by a Triassic conifer”; Andrew B. Schwendemann, Anna-Laure Decombeix, Thomas N. Taylor, Edith L. Taylor & Michael Krings; Proceedings of the National Academy of Sciences of the United States of America 108(33): 13630–13634 (2011).
Prof. Dr. Michael Krings
Department für Geo- und Umweltwissenschaften
Paläontologie & Geobiologie
Bayerische Staatssamlung für Paläontologie und Geologie
Phone: +49 (0) 89 2180 6546
Fax: +49 (0) 89 2180 6601