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Philos Trans R Soc Lond B Biol Sci. 2018 Feb 5;373(1739). pii: 20160502. doi: 10.1098/rstb.2016.0502.

New insights into the evolutionary history of Fungi from a 407 Ma Blastocladiomycota fossil showing a complex hyphal thallus.

Author information

1
Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK c.strullu-derrien@nhm.ac.uk.
2
Department of Earth Science and Engineering, Imperial College London, London, UK.
3
Imaging and Analysis Centre, The Natural History Museum, Cromwell Road, London SW7 5BD, UK.
4
Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4.
5
Institute of Plant and Microbiology, University of Zürich, Zollikerstrasse 107, 8008 Zürich, Switzerland.
6
Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK.
7
School of Biology and Ecology, University of Maine, 5722 Deering Hall, Orono, ME, USA.
8
Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 mary.berbee@gmail.com.

Abstract

Zoosporic fungi are key saprotrophs and parasites of plants, animals and other fungi, playing important roles in ecosystems. They comprise at least three phyla, of which two, Chytridiomycota and Blastocladiomycota, developed a range of thallus morphologies including branching hyphae. Here we describe Retesporangicus lyonii gen. et sp. nov., an exceptionally well preserved fossil, which is the earliest known to produce multiple sporangia on an expanded hyphal network. To better characterize the fungus we develop a new method to render surfaces from image stacks generated by confocal laser scanning microscopy. Here, the method helps to reveal thallus structure. Comparisons with cultures of living species and character state reconstructions analysed against recent molecular phylogenies of 24 modern zoosporic fungi indicate an affinity with Blastocladiomycota. We argue that in zoosporic fungi, kinds of filaments such as hyphae, rhizoids and rhizomycelium are developmentally similar structures adapted for varied functions including nutrient absorption and anchorage. The fossil is the earliest known type to develop hyphae which likely served as a saprotrophic adaptation to patchy resource availability. Evidence from the Rhynie chert provides our earliest insights into the biology of fungi and their roles in the environment. It demonstrates that zoosporic fungi were already diverse in 407 million-year-old terrestrial ecosystems.This article is part of a discussion meeting issue 'The Rhynie cherts: our earliest terrestrial ecosystem revisited'.

KEYWORDS:

Blastocladiomycota; Chytridiomycota; confocal laser scanning microscopy; fossil fungus; hyphae; phylogeny

PMID:
29254966
PMCID:
PMC5745337
DOI:
10.1098/rstb.2016.0502
[Indexed for MEDLINE]
Free PMC Article

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