Acaulosporoid glomeromycotan spores with a germination shield from the 400-million-year-old Rhynie chert

Abstract

This work has been made available by the University of Kansas Libraries' Office of Scholarly Communication and Copyright. Please share your stories about how Open Access to this article benefits you.This is the published version of the article, made available with the permission of the publisher. The original published version can be found at the link below. Dotzler, N., Walker, C., Krings, M., Hass, H., Kerp, H., Taylor, T., Agerer, R. 2009. Acaulosporoid glomeromycotan spores with a germination shield from the 400-million-year-old Rhynie chert. Mycol Progress 8:9-18. Abstract Scutellosporites devonicus from the Early Devonian Rhynie chert is the only fossil glomeromycotan spore taxon known to produce a germination shield. This paper describes a second type of glomeromycotan spore with a germination shield from the Rhynie chert. In contrast to S. devonicus, however, these spores are acaulosporoid and develop laterally in the neck of the sporiferous saccule. Germination shield morphology varies, from plate-like with single or double lobes to tongue-shaped structures usually with infolded margins that are distally fringed or palmate. Spore walls are complex and appear to be constructed of at least three wall groups, the outermost of which includes the remains of the saccule. The complement of features displayed by the fossils suggests a relationship with the extant genera Ambispora, Otospora, Acaulospora or Archaeospora, but which of these is the closest extant relative cannot be determined. The acaulosporoid spores from the Rhynie chert document that this spore type was in existence already ∼400 mya, and thus contribute to a more complete understanding of the evolutionary history of the Glomeromycota. This discovery pushes back the evolutionary origin of all main glomeromycotan groups, revealing that they had evolved before rooted land plants had emerged.

Oldest fossil basidiomycete clamp connections

“…There is little doubt that multiple lineages of fungi and fungus-like microorganisms predate their documented existence in the fossil record, and that at least some of the genetic, biochemical, and structural features defining modern groups diverged early and appear to have remained relatively unchanged in modern forms (Bonfante and Genre 2008;Dotzler et al 2009). The Visean clamp connections add support to this hypothesis.…”

Contrasting arbuscular mycorrhizal responses of vascular and non-vascular plants to a simulated Palaeozoic CO2 decline

“…This requirement has driven the establishment of symbiotic partnerships between soil-dwelling fungi and the earliest land plants (embryophytes) to increase the uptake of P ever since plants' initial conquest of the land 5,6,7 . Intercellular hyphae and arbuscules have been documented in gametophytes and sporophytes from the Early Devonian Rhynie chert flora, together with exceptionally well-preserved spores representative of several of the major glomeralean fungal groups 8,9,10,11,12 . These associations with AM fungi formed under a CO 2 -rich atmosphere, even before true roots evolved around 400 Myr, ago (Fig.…”

Origins of the terrestrial flora: A symbiosis with fungi?

“…407 Myrs ago) that fossils allow investigations of tissues at the cellular level. The presence of Glomeromycetes is well established in the Rhynie Chert [18,38,39]. Moreover, Glomeromycetes colonization, with intercellular hyphae, arbuscules and vesicles has been reported from some plant aerial axes [40][41][42] (Fig.…”