Fossil ectomycorrhizae from the Middle Eocene

Abstract

Fossil ectomycorrhizae were found recently among permineralized plant remains in the middle Eocene Princeton chert of British Columbia. The ectomycorrhizae are associated with roots of Pinus and have a Hartig net that extends to the endodermis, a pseudoparenchymatous mantle, and contiguous extramatrical hyphae that are simple-septate. The mycorrhizal rootlets lack root hairs and dichotomize repeatedly to form large, coralloid clusters. Reproductive structures are absent. Based on the morphological characteristics, and the identity of the host, the closely related basidiomycete genera Rhizopogon and Suillus are suggested as comparable extant mycorrhizal fungi. These exquisitely preserved specimens represent the first unequivocal occurrence of fossil ectomycorrhizae and demonstrate that such associations were well-established at least 50 million years ago.

A review of the plants of the Princeton chert (Eocene, British Columbia, Canada)

“…Fungi are also well known in the chert, both for their taxonomic diversity and varied ecological roles (LePage et al 1994(LePage et al , 1997Currah and Stockey 1991;Currah et al 1998;Stockey et al 2001;Klymiuk et al 2013aKlymiuk et al , 2013b. The occurrence, taxonomic diversity, and consideration of the potential ecological roles of Princeton chert fungi are summarized in Klymiuk et al (2013aKlymiuk et al ( , 2013b and Klymiuk (2014Klymiuk ( , 2016.…”

“…Benoit A. LePage worked as a postdoctoral associate in the Stockey lab in the early and mid 1990s and collaboratively studied Diplopanax eydei Stockey, LePage & Pigg (Cornaceae, Stockey et al 1998). Mycologist Randy Currah collaborated with Stockey, LePage, and others in an analysis of the fossil fungi in the Princeton chert (Currah and Stockey 1991;LePage et al 1994LePage et al , 1997Currah et al 1998;Stockey et al 2001). (It should be noted that specimens described as smut fungi from the anthers of small flowers (Currah and Stockey 1991) turned out to be the pollen grains of Saururus tuckerae (Smith andStockey 2007a, 2007b (Little 2006;Smith 2007).…”

Oldest fossil basidiomycete clamp connections

“…Provided that the estimate by Berbee and Taylor (2001) of 500 Ma as a minimum age for Basidiomycota as a distinct lineage is accurate, it is reasonable to assume that these fungi were also important elements in ancient continental ecosystems, at least from the Early Devonian onward. However, fossil evidence for this hypothesis has been exceedingly slow to accumulate, and is largely restricted to records from the Mesozoic (Osborn et al 1989;Hibbett et al 1997;Krassilov and Makulbekov 2003;Poinar and Brown 2003;Smith et al 2004) and Cenozoic (Poinar and Singer 1990;Magallón-Puebla and Cevallos-Ferriz 1993;LePage et al 1997;Hibbett et al 2003;Fleischmann et al 2007). To date the oldest undisputed basidiomycete body fossil is Palaeancistrus martinii from the Middle Pennsylvanian (Dennis 1969(Dennis , 1970.…”

Convergence in Multispecies Interactions

“…ECM symbioses evolved as recently as 50 Mya [34,35]. The associations evolved repeatedly and independently in the ascomycetes and basidiomycetes [11]; in the latter, ECM associations evolved at least 14 times in at least eight orders (Box 1).…”