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Prototaxites: A 400 MYR Old Giant Fossil, A Saprophytic Holobasidiomycete, or A Lichen?
... Given the small stature of Silurian-Devonian land plants, some have argued that strict saprotrophy would have been unlikely and instead favored interpretation of Prototaxites as a lichen association with a photosynthetic symbiont (Selosse 2002). This was expanded upon by suggesting algae were housed in leaflike appendages that escaped fossilization (Selosse and Strullu-Derrien 2015;Honegger et al. 2018). ...
... Molecular clock studies among the fungi were few and in an early stage when Prototaxites was first suggested to be a basidiomycete sporocarp (Hueber 2001) and an ascomycete lichen posited as an alternative (Selosse 2002). Subsequent efforts leveraging more advanced methods, larger data sets, and more calibrations have provided an opportunity to place the age of Silurian-Devonian Prototaxites in a modern context and understanding of the evolution of fungal clades and morphologies. ...
... Instead, strict saprotrophy remains the simplest option. The original argument for a lichenized Prototaxites was framed in the context of meager early vegetation, which would have contributed little biomass to support a massive saprotroph (Selosse 2002). However, there is no reason to assume Prototaxites growth was rapid. ...
... Two other interpretations of Prototaxites as kelp-like aquatic alga (Schweitzer 1983) and rolled up carpets of liverworts (Graham et al. 2010) have been effectively falsified by Taylor et al. (2009 because of continuous dense tissues and shape like a load-bearing, tapering trunk. This study addresses two other interpretations of Prototaxites as enormous saprophytic fungal fruiting bodies (Hueber 2001, Boyce et al. 2007, Hobbie and Boyce 2010 or as giant lichen podetia (Retallack 1994, Selosse 2002. These two alternatives are tested herein by carbon isotopic analyses, thin section and scanning electron microscopic re-examination of an especially complete and well preserved example of Prototaxites loganii collected during the 19th century as the ''Skunnemunk tree'' (Ries 1897, Nevius 1900, Prosser 1902) and now in the New York State Museum in Albany. ...
... Retallack (1994Retallack ( , 2007 argued from the resistance to burial compaction of tubular cells of Prototaxites that it had a strong biopolymer, such as chitin found in fungal hyphae, and that rounded vacuities within cortical nests once included coccoid photobionts. Selosse (2002) elaborated on this lichen interpretation with nutritional arguments that such a large fungus needed a larger reservoir of organic carbon than associated early land plants, unless it was lichenized. The nutritional argument finds support in discovery of Prototaxites-like rhizomorphs in carbon-lean, red paleosols (Driese andMora 2001, Hillier et al. 2008). ...
... Other hypotheses for isotopic variability come from lichenization, as proposed for Prototaxites by Retallack (1994) and Selosse (2002). Lichens with cyanobacterial photobionts such as Nostoc and Gloeocapsa are isotopically heavy (Smith et al. 1998), comparable to Kranz anatomy (C 4 ) plants (Vogel et al. 1977). ...
Devonian fossil logs of Prototaxites loganii have been considered kelp-like aquatic algae, rolled up carpets of liverworts, enormous saprophytic fungal fruiting bodies or giant lichens. Algae and rolled liverwort models cannot explain the proportions and branching described here of a complete fossil of Prototaxites loganii from the Middle Devonian (386 Ma) Bellvale Sandstone on Schunnemunk Mountain, eastern New York. The ''Schunnemunk tree'' was 8.83 m long and had six branches, each about 1 m long and 9 cm diam, on the upper 1.2 m of the main axis. The coalified outermost layer of the Schunnemunk trunk and branches have isotopic compositions (d 13 C PDB) of 225.03 6 0.13% and 226.17 6 0.69%, respectively. The outermost part of the trunk has poorly preserved invaginations above cortical nests of coccoid cells embraced by much-branched tubular cells. This histology is unlike algae, liverworts or vascular plants and most like lichen with coccoid chlorophyte phycobionts. Prototaxites has been placed within Basidiomycota but lacks clear dikaryan features. Prototaxites and its extinct order Nematophytales may belong within Mucoromycotina or Glomeromycota.
... Space experiments demonstrating survival of lichens under cosmic radiation (Sancho et al., 2007;Brandt et al., 2015Brandt et al., , 2017Meeßen et al., 2017), as well as the discovery of endolithic lichen microfossils in the Antarctic Ross Desert (Wierzchos and Ascaso, 2001;Ascaso and Wierzchos, 2002), put lichens in the center of investigations into the possible existence of extraterrestrial life. Although the fossil record of genuine lichens is sparse, many taxonomically challenging fossils ("Problematica"), including Proterozoic biocrusts, Precambrian Ediacarans, or the fungal-like megafossil Prototaxites, have often been considered to represent lichens (Retallack, 1994Selosse, 2002;Selosse and Strullu-Derrien, 2015;Beraldi-Campesi and Retallack, 2016;Honegger et al., 2017). ...
... About 70% of all putative lichen fossils are from amber; this proportion increases to nearly 90% when excluding ambiguous and rejected records (Table 23.1). Amber lichen fossils are known from Baltic, Bitterfeld, and Dominican amber, with a geological age range of (47e)38e20(e15) Ma (Göppert, 1845(Göppert, , 1852(Göppert, , 1853(Göppert, , 1854Schimper, 1869;Engelhardt, 1870;Göppert and Menge, 1883;Smith, 1921;Andree, 1951;Mägdefrau, 1957;Gothan and Weyland, 1973;Weitschat, 1979;Garty et al., 1982;Poinar et al., 2000;Rikkinen and Poinar, 2000, 2002, 2008Rikkinen, 2003;Beimforde et al., 2014;Hartl et al., 2015;Kaasalainen et al., 2015Kaasalainen et al., , 2017Kettunen et al., 2016). About 30% of all recorded amber lichen fossils have not been taxonomically identified, whereas another 30% have been broadly classified as Arthoniales, Lecanoromycetidae, Pertusariales, Parmeliaceae, or Physciaceae (Table 1; Kaasalainen et al., 2015Kaasalainen et al., , 2017. ...
... Eleven new taxa were established from amber fossils, all in extant genera, six of them validly described ( (Göppert, 1852(Göppert, , 1853Göppert and Menge, 1883;Mägdefrau, 1957;Poinar et al., 2000;Rikkinen and Poinar, 2000, 2002, 2008. Preservation in amber is not necessarily a guarantee for proper taxonomic assessment of fossil remains, as shown by the presumed lichen fossil A. succinii, which was suggested to resemble the extant lichen Bryoria subcana (Brodo and Hawksworth, 1977), but recently reinterpreted as of plant origin due to the presumed lack of evidence of fungal hyphae and photobiont cells in anatomical sections . ...
... American Journal of Botany 97 (7): 1079-1086, 2010; http://www.amjbot.org/ © 2010 Botanical Society of America Our investigations were stimulated in part by a previous article ( Selosse, 2002 ) that challenged earlier conclusions published by a commentary author that Prototaxites was the erect sporocarp of a basidiomycete fungus occasionally reaching surprisingly large size ( Hueber, 2001 ). For convenience, we here refer to Hueber ' s (2001) concept as the " sporocarp hypothesis. ...
... Taking an analogous approach to the sporocarp hypothesis, we point out that 8.8 m tall basidomycete sporocarps (or any even near that size) are not known to exist on Earth now, raising reasonable doubt that such occurred in the past. An equivalent challenge to advocates of the fungal sporocarp hypothesis might be to genetically alter a modern basidiomycete fungus so that it can produce cylindrical fruiting bodies at least 8.8 m tall and over a meter in diameter, then demonstrate that the sporocarps (lacking wood) can remain upright in windstorms, subject the sporocarps to experimental taphonomic studies to evaluate the extent to which internal anatomy resists degradation and refl ects Prototaxites anatomy, and show why reproductive traits predicted by the sporocarp hypothesis are not readily observed in the fossils ( Selosse, 2002 ). We suggest an alternative method for evaluating the rolled mat hypothesis. ...
... In contrast, large-diameter skeletal hyphae of the holobasidiomycete polypore Ganoderma lucidum , though having relatively thick and electron-dense walls, lack ultrastructural patterning similar to that of Prototaxites and appear collapsed (see fi g. 16 in Mims and Seabury, 1989 ). These dissimilarities provide previously unrecognized bases for questioning the sporophore hypothesis, which specifi cally identifi es the larger tubes of Prototaxites as skeletal hyphae ( Hueber, 2001 ), adding to the issues raised by Selosse (2002) . ...
In volume 97(2) of the American Journal of Botany (pp. 268-275), we published an article entitled "Structural, physiological, and stable carbon isotopic evidence that the enigmatic Paleozoic fossil Prototaxites formed from rolled liverwort mats". Here, we respond to a letter and a commentary on our article in the present issue, welcoming this opportunity to continue the scientific dialogue about an issue that has long been stimulating and controversial. For the reader's benefit, we first briefly describe the recent scholarly context of our article.
... Taxa display a pseudoparenchymatous construction wherein aggregations of tubes and cuticles comprise the plant body. Nematophytes remain largely enigmatic although some are considered ascomycetes (Honegger et al., 2017), some lichenized-fungi (Honegger et al., 2013;Edwards et al., 2018), or basidiomycetes (Hueber, 2001), whereas others are interpreted as saprophytic holobasdiomycetes, lichens (Selosse, 2002) or as of fungal origin but lacking extant descendants (Nelsen and Boyce, 2022). The first robust evidence of lichenized-fungi comes from the basal Přídolí-aged sediments at Ludford Lane in the United Kingdom (UK). ...
... calculated from a composite of the experimental 1-24 hr duration charring data in Scott and Glasspool (2005) and, Equation 2) y = 1.5242x 3 -9.0073x 2 + 116.22x + 300.66 based upon experimental chars of the modern bracket fungus Ganoderma (Scott and Glasspool, 2007;Glasspool and Gastaldo, 2022). The calibration data based upon Ganoderma are more limited in extent but may better represent the original cell-wall chemistry of nematophytes and, in particular, Prototaxites with which bracket fungus has been compared (Selosse, 2002;Boyce et al., 2007). Further discussion of these equations is given in the Supplemental Data of Glasspool and Gastaldo (2022). ...
Charred fossils from the Wenlock (Wales) and Ludlow (Poland) are evidence of the earliest wildfires to date, showing this phenomenon was contemporaneous with the earliest records of land plant macrofossils. These data indicate fires began to influence Earth system processes alongside those wrought by the advent of an embryophytic terrestrial flora. By the mid-Silurian, fires affected atmospheric composition, sedimentary systems, carbon-and-nutrient cycling, landscape diversity, community composition, and species interactions. As global-heating alters wildfire regimes, greater recognition is being given to fires and their ecosystem impacts, a relationship we now know extends back >430 million years.
Here we document the taxonomic composition of charred phytoclasts, evidence of wildfire activity, from two discrete Silurian localities–the Pen-y-lan Mudstone, Rumney, Wales, and the Winnica Formation, Holy Cross Mountains, Poland. Nematophytes dominate each mesofossil assemblage and quantitative reflectance data indicate generally low-temperature fires at both sites, but with locally intense conditions. These and other Silurian assemblages, herein documented as bearing-charcoal, are used to evaluate the systematics, fuel load, and burn temperatures of these earliest wildfires. We propose a diagrammatic reconstruction to explain the seeming disparity between the diminutive size of the embryophytic biota and the highest temperatures (>700˚ C) recorded in these charcoals.
Supplementary material: [Raw Mean Random Reflectance (R o %) data from Rumney Borehole, Winnica, Ludford Lane and North Brown Clee Hill sorted by both Locality and Morphotype] is available at: https://doi.org/10.6084/m9.figshare.c.6179309
... The genus Prototaxites was widespread, fossils having been found, e.g. in the Scottish Rhynie Cherts, in Red Sandstone of Wales, Holland, Belgium and Germany (Eifel, Taunus, etc.), in Gaspé (Cana- da), New York State (USA), Saudi Arabia, Australia. Prototaxites was inter- preted as a giant marine alga, rolled carpets of liverworts, a fungus or a lichen (EDWARDS 1982, HUEBER 2001, SELOSSE 2002, GRAHAM et al. 2010, HOBBIE & BOYCE 2010, review: STEUR 2015. Due to structural similarities with Ne- matophytes, an extinct, presumably lichenized group of fungi, wide spread members of cryptogamic covers from the mid-Ordovician to Late Devonian, Prototaxites was interpreted as a member of Nematophytales (ED WARDS et al. 2013, RETALLACK & LANDING 2014). ...
... Currently no-one can explain how a predominantly fungal axis should have been able to stand more than 8 m high. The lichen hypothesis (SELOSSE 2002, HOBBIE & BOYCE 2010 gives an idea about the nutritional strategy of these extinct, impressive, presumably hete- rotrophic organisms. ...
A short overview on fossil lichens and lichen-like organisms from Cenozoic amber to the Proterozoic Doushantuo fossils is presented. The focus is on structural pe-culiarites of Cyanolichenomycites devonicus and Chlorolichenomycites salopensis, fossil cyanobacterial and green algal lichens from the Lower Devonian (Lochkovian, approx. 415 Myr old), the earliest lichens with heteromerous thallus anatomy found up to now, and their bacterial and fungal epi-and endobionts, as seen in scanning electron micro-scopy preparations. sediments of the Welsh borderland. The microbiome of C. salopensis was ultrastruc-turally investigated: bacterial colonies were found on the surface of the cortical layer, the phylogeny, biology and potential economic importance of the microbiome of extant lichens is currently intensely investigated by various teams worldwide.
... Was bisher jedoch weder an den Fossilien selbst noch in ihrem jeweiligen Umfeld nachgewiesen werden konnte, sind Sporen, wie sie eigentlich an einem Pilz-Fruchtkörper zu erwarten wären. Dies ist einer der Fakten, die Selosse (2002) an der Zuordnung zu einer der bekannten Pilzgruppen zweifeln ließ. Er bezweifelte außerdem, dass ein sich rein heterotroph ernährender Pilz zum Aufbau derart gigantischer Fruchtkörper imstande gewesen sein konnte. ...
... Nahrungssubstrats aufwiegt. Selosse (2002) hielt deswegen eine Zuordnung von Prototaxites zu den Flechten (3) für wahrscheinlicher; einer symbiotischen Vergesellschaftung eines Pilzes mit zur Photosynthese und somit autotropher Ernährung befähigten Organismen (z. B. Algen). ...
Fossils of giant Prototaxites are known from Late Silurian to Upper Devonian deposits worldwide. The organism´s nature still remains enigmatic. According to recent research it probably was a fungus- or lichen-like creature which inhabited terrestrial environments ranging from kryptobiotic grounds to densely vegetated riverbeds. Appropriate deposits are missing in the Lower Devonian of the Rhenish Slate Mountains. However several finds give evidence that Prototaxites thrived around the marine-dominated rhenish environment at that time. As a rule these fossils are fractured which indicates a more or less far transportation before their deposition. Numerous finds are known from the Siegenian-aged Taunusquarzit deposits which had been deposited in a flat sea in the North of the so-called Mitteldeutsche Schwelle from which the deposits were washed in. According to that there must have been adequate environments on that ridge. Prototaxites finds in gravels of a Cenozoic paleo-riverbed in the Southern Eifel Mountains are supposed to originate from eroded Taunusquarzit deposits in the Southern Hunsrück Mountains. Other Cenozoic Prototaxites gravels found near Bonn (Uckerath) supposedly originate from eroded Siegenian-aged delta-deposits in the nearby Northern Westerwald Mountains the fossil record of which gives evidence of temporarily terrestrial conditions. The Prototaxites remains here might have been washed in by a river from the paleo-continent Laurussia or derive from stably silted up areas within the delta. Similar paleo-environmental conditions are assumed for the deltaic deposits of the late Lower Emsian Klerf beds in the Western Eifel Mountains putatively bearing Prototaxites such as the same-aged Nellenköpfchen beds around Koblenz. The latter might have been the origin of Prototaxites-remains found in fully-marine early Upper Emsian Emsquarzit deposits between Koblenz and Montabaur which were deposited after the deltaic and tidal environments of the Nellenköpfchen beds had been flooded by a transgression.
Citation:
ALBERTI, M. (2017): Prototaxites – Mysteriöse Riesen aus dem rheinischen Unterdevon. – Fossilien 34 (5); 8-17
... Chaenotheca Th. Fr. is placed in the Coniocybaceae, but its exact position has not been clarified (Tibell 1999a, 2002, Tibell and Beck 2002, Tibell and Koffman 2002. ...
... However, the oldest fossils of both ascomycetes and lichens are known from the early Devonian Period, more than 400 MaBP (Taylor et al 1997(Taylor et al , 1999. The first lichen symbioses might have evolved even earlier (Selosse 2002). Recent molecular clock estimates have indicated that the major lineages of Fungi already had evolved 1000 MaBP (Heckman et al 2001). ...
Two species of calicioid lichens (Ascomycota) are reported from Baltic amber dating back 55–35 million years ago. The fossils are very similar to some modern Calicium and Chaenotheca species, but because ascus characteristics and photobiont identities cannot be determined they are not assigned to any extant species. Calicioid lichens seem to show a conservative maintenance of morphological adaptations to successful ecological niches, as do several other groups of ascomycetes. The fossils demonstrate that distinguishing features in the morphology of both genera have remained unchanged for at least tens of millions of years. The palaeohabitat of the fossil lichens, viz. that of conifer trunks in a humid, mixed forest, is consistent with the habitat preferences of many modern Calicium and Chaenotheca species.
... Two other interpretations of Prototaxites as kelp-like aquatic alga (Schweitzer 1983) and rolled up carpets of liverworts (Graham et al. 2010) have been effectively falsified by Taylor et al. (2009 because of continuous dense tissues and shape like a load-bearing, tapering trunk. This study addresses two other interpretations of Prototaxites as enormous saprophytic fungal fruiting bodies (Hueber 2001, Boyce et al. 2007, Hobbie and Boyce 2010 or as giant lichen podetia (Retallack 1994, Selosse 2002. These two alternatives are tested herein by carbon isotopic analyses, thin section and scanning electron microscopic re-examination of an especially complete and well preserved example of Prototaxites loganii collected during the 19th century as the "Skunnemunk tree" (Ries 1897, Nevius 1900, Prosser 1902) and now in the New York State Museum in Albany. ...
... Prototaxites by Retallack (1994) and Selosse (2002). Lichens with cyanobacterial photobionts such as Nostoc and Gloeocapsa are isotopically heavy (Smith et al. 1998), comparable to Kranz anatomy (C 4 ) plants (Vogel et al. 1977). ...
Devonian fossil logs of Prototaxites loganii have been considered kelp-like aquatic algae, rolled up carpets of liverworts, enormous saprophytic fungal fruiting bodies or giant lichens. Algae and rolled liverwort models cannot explain the proportions and branching described here of a complete fossil of Prototaxites loganii from the Middle Devonian (386 Ma) Bellvale sandstone on Schunnemunk Mountain, eastern New York. The "Schunnemunk tree" was 8.83 m long and had six branches, each about 1 m long and 9 cm diam, on the upper 1.2 m of the main axis. The coalified outermost layer of the Schunnemunk trunk and branches have isotopic compositions (δ13CPDB) of -25.03 ± 0.13‰ and -26.17 ± 0.69‰, respectively. The outermost part of the trunk has poorly preserved invaginations above cortical nests of coccoid cells embraced by much-branched tubular cells. This histology is unlike algae, liverworts or vascular plants and most like lichen with coccoid chlorophyte phycobionts. Prototaxites has been placed within Basidiomycota but lacks clear dikaryan features. Prototaxites and its extinct order Nematophytales may belong within Mucoromycotina or Glomeromycota.
... However, the oldest fossils of both ascomycetes and lichens are known from the early Devonian Period, more than 400 MaBP (Taylor et al 1997, 1999). The first lichen symbioses might have evolved even earlier (Selosse 2002). Recent molecular clock estimates have indicated that the major lineages of Fungi already had evolved 1000 MaBP (Heckman et al 2001). ...
... However, the oldest fossils of both ascomycetes and lichens are known from the early Devonian Period, more than 400 MaBP (Taylor et al 1997Taylor et al , 1999). The first lichen symbioses might have evolved even earlier (Selosse 2002 ). Recent molecular clock estimates have indicated that the major lineages of Fungi already had evolved 1000 MaBP (Heckman et al 2001). ...
Two species of calicioid lichens (Ascomycota) are reported from Baltic amber dating back 55-35 million years ago. The fossils are very similar to some modern Calicium and Chaenotheca species, but because ascus characteristics and photobiont identities cannot be determined they are not assigned to any extant species. Calicioid lichens seem to show a conservative maintenance of morphological adaptations to successful ecological niches, as do several other groups of ascomycetes. The fossils demonstrate that distinguishing features in the morphology of both genera have remained unchanged for at least tens of millions of years. The palaeohabitat of the fossil lichens, viz. that of conifer trunks in a humid, mixed forest, is consistent with the habitat preferences of many modern Calicium and Chaenotheca species.
... Boyce et al. (2007) obtained variable δ 13 C isotope values from Prototaxites, suggesting heterotrophic nutrition on isotopically distinct substrates consistent with a fungal affinity. Most recent interpretations have converged on Prototaxites being either a fungal fruiting body or large lichen (Selosse 2002;Nelsen and Boyce 2022). In summary, Nematophytales (including Prototaxites) have no clear affinities with extant groups but probably constitute a fully extinct array of fungi (Edwards and Axe 2012). ...
The enigmatic fossil Prototaxites found in successions ranging from the Middle Ordovician to the Upper Devonian was originally described as having conifer affinity. The current debate, however, suggests that they probably represent gigantic algal–fungal symbioses. Our re-investigation of permineralized Prototaxites specimens from two localities, the Heider quarry in Germany and the Bordeaux quarry in Canada, reveals striking anatomical similarities with modern fungal rhizomorphs Armillaria mellea. We analysed extant fungal rhizomorphs and fossil Prototaxites through light microscopy of their anatomy, Fourier transform infrared spectroscopy, X-ray microscopy, and Raman spectroscopy. Based on these comparisons, we interpret the Prototaxites as fungi. The detailed preservation of cell walls and possible organelles seen in transverse sections of Prototaxites reveal that fossilization initiated while the organism was alive, inhibiting the collapse of delicate cellular structures. Prototaxites has been interpreted to grow vertically by many previous workers. Here we propose an alternative view that Prototaxites represents a complex hyphal aggregation (rhizomorph) that may have grown horizontally similar to modern complex aggregated mycelial growth forms, such as cords and rhizomorphs. Their main function was possibly to redistribute water and nutrition from nutrient-rich to nutrient-poor areas facilitating the expansion for early land plant communities.
... The abundant Bukowa Góra fossils could shed new light on the affinities of these filamentous fossils. Among the associated macrofossils, we documented permineralized remains resembling Prototaxites, which is an enigmatic organism variously interpreted as a fungal sporophore (e.g., Hueber, 2001;Honegger et al., 2018) or a lichenised fungus (Selosse, 2002), but also, perhaps in part, belonging to an extinct group that is not closely related to fungi (Selosse and Strullu-Derrien, 2015). Prototaxites is usually associated with terrestrial deposits (Griffing et al., 2000;Hotton et al., 2001), and it is widely recorded through much of the Devonian Period (Hueber, 2001). ...
We present a preliminary assessment of a new Lower Devonian biota from an exposure of the Zagórze Formation at Bukowa Góra quarry in the Łysogóry Region of the Holy Cross Mountains, Poland. Abundant plant macrofossils preserved as carbonaceous compressions, adpressions, and permineralizations occur alongside a diverse assemblage of microfossils. Palynostratigraphic analysis places the fossiliferous sequences in the narrow Pro. Zone within the AP Zone of the douglastownense-eurypterota Miospore Zone, which corresponds to the upper part of the Emsian. Palynofacies analysis confirms that these sediments formed in a shallow-water, alluvial environment. The biota contains a rich assemblage of freshwater and brackish water organisms and fully terrestrial ones. Common elements include filamentous green algae, arthropods, terrestrial fungi-like filaments, nematophytes and abundant land plants. Scolecodonts and acritarchs are much rarer, suggesting limited marine influence. The new flora contains stem-group vascular plants, lycophytes and euphyllophytes. Among the permineralized remains is some of the earliest evidence of complex vascular systems, including cruciform and plate-like stelar organizations and secondary wood. We record the earliest fossil evidence of a dissected stele of the cladoxylopsid type. Innovations such as these were fundamental to the later evolution of arborescent growth in plants and the development of forest ecosystems. The biota complements and extends our knowledge of Emsian biotas in Euramerica just prior to the rapid changes that marked the Middle Devonian. It provides insights into a diverse early terrestrial community and raises further questions about the affinities and roles of arthropods and nematophytales in these ecosystems.
... Hobbie and Boyce 123 concluded that the carbon isotope ratios of Prototaxites indicated that it was a saprotrophic fungus. Selosse argued that the surrounding Devonian primary producers could not have supported such a large saprotroph, and suggested that lichenization, which would have enabled carbon acquisition from algal partners, was more likely 124 . ...
Fungi have crucial roles in modern ecosystems as decomposers and pathogens, and they engage in various mutualistic associations with other organisms, especially plants. They have a lengthy geological history, and there is an emerging understanding of their impact on the evolution of Earth systems on a large scale. In this Review, we focus on the roles of fungi in the establishment and early evolution of land and freshwater ecosystems. Today, questions of evolution over deep time are informed by discoveries of new fossils and evolutionary analysis of new genomes. Inferences can be drawn from evolutionary analysis by comparing the genes and genomes of fungi with the biochemistry and development of their plant and algal hosts. We then contrast this emerging picture against evidence from the fossil record to develop a new, integrated perspective on the origin and early evolution of fungi.
... Neolecta shares approximately 1000 genes with filamentous Pezizomycotina that are absent in yeast-like members of the Taphrinomycotina, with this set mostly enriched in genes relating to endomembrane systems (Nguyen et al., 2017). Some studies have suggested that the fossil Prototaxites [420-370 million years ago (Mya)] (Hueber, 2001;Selosse, 2002) is affiliated to Neolectomycetes based on structural characters (Honegger et al., 2018). Under that interpretation, Prototaxites represents fruiting bodies or vegetative thalli of an unspecified lineage within the Ascomycota, and is probably a member of the Taphrinomycotina. ...
The question of how phenotypic and genomic complexity are inter‐related and how they are shaped through evolution is a central question in biology that historically has been approached from the perspective of animals and plants. In recent years, however, fungi have emerged as a promising alternative system to address such questions. Key to their ecological success, fungi present a broad and diverse range of phenotypic traits. Fungal cells can adopt many different shapes, often within a single species, providing them with great adaptive potential. Fungal cellular organizations span from unicellular forms to complex, macroscopic multicellularity, with multiple transitions to higher or lower levels of cellular complexity occurring throughout the evolutionary history of fungi. Similarly, fungal genomes are very diverse in their architecture. Deep changes in genome organization can occur very quickly, and these phenomena are known to mediate rapid adaptations to environmental changes. Finally, the biochemical complexity of fungi is huge, particularly with regard to their secondary metabolites, chemical products that mediate many aspects of fungal biology, including ecological interactions. Herein, we explore how the interplay of these cellular, genomic and metabolic traits mediates the emergence of complex phenotypes, and how this complexity is shaped throughout the evolutionary history of Fungi.
... Lichens are pioneer symbiotic organisms of primary succession that can survive in all terrestrial environments, including those with extreme climates such as the Arctic, Antarctic, high alpine, and desert (Ahmadjian, 1993;Longton, 1988), and they dominate ~10% of the Earth's land surface (Honegger, 2006), particularly in marginal environments. Lichens contribute to the local and global carbon budget (Ahmadjian, 1995) and may have played a critical role during the development of the early terrestrial landscape before higher plants colonized the land (Selosse, 2002; Selosse, Strullu-Derrien, Martin, Kamoun, & Kenrick, 2015). Periods of lichens' photosynthesis and growth are limited by the duration and frequency of their hydrated, active periods (Dahlman & Palmqvist, 2003;Palmqvist & Sundberg, 2000), and the magnitude of their photosynthetic assimilation is suppressed at low thallus water contents (Lange, Green, & Heber, 2001). ...
Algal‐fungal symbionts share water, nutrients and gases via an architecture unique to lichens. Because lichen activity is controlled by moisture dynamics, understanding water transport is prerequisite to understanding their fundamental biology. We propose a model of water distributions within foliose lichens governed by laws of fluid motion. Our model differentiates between water stored in symbionts, on extracellular surfaces, and in distinct morphological layers. We parameterize our model with hydraulic properties inverted from laboratory measurements of Flavoparmelia caperata and validate for wetting and drying. We ask: (1) Where is the bottleneck to water transport? (2) How do hydration and dehydration dynamics differ, and (3) what causes these differences? Resistance to vapor flow is concentrated at thallus surfaces and acts as the bottleneck for equilibrium, while internal resistances are small. The model captures hysteresis in hydration and desiccation, which are shown to be controlled by nonlinearities in hydraulic capacitance. Muting existing nonlinearities slowed drying and accelerated wetting, while exaggerating nonlinearities accelerated drying and slowed wetting. The hydraulic nonlinearity of Flavoparmelia caperata is considerable, which may reflect its preference for humid and stable environments. The model establishes the physical foundation for future investigations of transport of water, gas, and sugar between symbionts.
... Devonian Period ecosystems also contained important and unique organisms whose affinities and biology remain obscure. Prototaxites and related fossils, which were up to 8-10 m tall, may represent gigantic algal-fungal symbioses (Selosse, 2002;Honegger et al., 2017). They disappeared when the first trees evolved, in the Mid-Devonian (350 million yr ago). ...
The ability of fungi to form mycorrhizas with plants is one of the most remarkable and enduring adaptations to life on land. The occurrence of mycorrhizas is now well established in c. 85% of extant plants, yet the geological record of these associations is sparse. Fossils preserved under exceptional conditions provide tantalizing glimpses into the evolutionary history of mycorrhizas, showing the extent of their occurrence and aspects of their evolution in extinct plants. The fossil record has important roles to play in establishing a chronology of when key fungal associations evolved and in understanding their importance in ecosystems through time. Together with calibrated phylogenetic trees, these approaches extend our understanding of when and how groups evolved in the context of major environmental change on a global scale. Phylogenomics furthers this understanding into the evolution of different types of mycorrhizal associations, and genomic studies of both plants and fungi are shedding light on how the complex set of symbiotic traits evolved. Here we present a review of the main phases of the evolution of mycorrhizal interactions from palaeontological, phylogenetic and genomic perspectives, with the aim of highlighting the potential of fossil material and a geological perspective in a cross‐disciplinary approach.
... Based solely on energy relationships, Selosse [70,71] had suggested a lichen-type association in Prototaxites, an affinity reinforced on very tenuous anatomical grounds by Retallack & Landing [10], but a sufficiently large and productive photobiont cell population has not yet been convincingly demonstrated. However, as in the other genera of nematophytes [33], the photobiont cell population might not have been preserved during fossilization. ...

The affinities of Prototaxites have been debated ever since its fossils, some attaining tree-trunk proportions, were discovered in Canadian Lower Devonian rocks in 1859. Putative assignations include conifers, red and brown algae, liver- worts and fungi (some lichenised). Detailed anatomical investigation led to the reconstruction of the type species, P. logani, as a giant sporophore (basidioma) of an agaricomycete (1⁄4 holobasidiomycete), but evidence for its reproduction remained elusive. Tissues associated with P. taiti in the Rhynie chert plus charcoalified fragments from southern Britain are investigated here to describe the reproductive characters and hence affinities of Prototaxites. Thin sections and peels (Pragian Rhynie chert, Aberdeenshire) were examined using light and confocal microscopy; Pridoli and Lochkovian charcoalified samples (Welsh Borderland) were liberated from the rock and examined with scanning electron microscopy. Prototaxites taiti possessed a superficial hymenium comprising an epihymenial layer, delicate septate paraphyses, inoperculate polysporic asci lacking croziers and a subhymenial layer composed predomi- nantly of thin-walled hyphae and occasional larger hyphae. Prototaxites taiti combines features of extant Taphrinomycotina (Neolectomycetes lacking cro- ziers) and Pezizomycotina (epihymenial layer secreted by paraphyses) but is not an ancestor of the latter. Brief consideration is given to its nutrition and potential position in the phylogeny of the Ascomycota.

... The fossil record seems at odds with the molecular dating approaches, with fossils being interpreted as lichens such as Thucomyces (Hallbauer and van Warmelo 1974;Hallbauer, Jahns, and Beltman 1977) and lichen-like fossils (Yuan, Xiao, and Taylor 2005) from the Proterozoic, the genus Farghera from the Cambrian-Ordovician boundary (Retallack 2009), and thalloid impressions from the early Silurian (Tomescu and Rothwell 2006)-all of them existed well before the classes originated that contain extant lichens. In addition, the Paleozoic Prototaxites (Taylor and Osborn 1996;Selosse 2002;Boyce et al. 2007; Edwards, Axe, and Honegger 2013; Retallack and Landing 2014) has been repeatedly suggested to represent a lichen-like organism. ...
... The fossil record seems at odds with the molecular dating approaches, with fossils being interpreted as lichens such as Thucomyces (Hallbauer and van Warmelo 1974;Hallbauer, Jahns, and Beltman 1977) and lichen-like fossils (Yuan, Xiao, and Taylor 2005) from the Proterozoic, the genus Farghera from the Cambrian-Ordovician boundary (Retallack 2009), and thalloid impressions from the early Silurian (Tomescu and Rothwell 2006)-all of them existed well before the classes originated that contain extant lichens. In addition, the Paleozoic Prototaxites (Taylor and Osborn 1996;Selosse 2002;Boyce et al. 2007; Edwards, Axe, and Honegger 2013; Retallack and Landing 2014) has been repeatedly suggested to represent a lichen-like organism. ...
... (1) Are distinctive features of modern glomalean fungi sufficiently resistant to expect their presence in the fossil record and from acid treated mineral matrices (as reported for the Or-dovician in Redecker et al. 2000Redecker et al. , 2002? (2) Are hyphae present in sporocarps of the modern basidiomycete Ganoderma sufficiently resistant to justify classifying the Silurian-Devonian macrofossil Prototaxites as the giant sporophore (basidiocarp, fruiting body) of a Ganoderma-like fungus (suggested in Hueber 2001)? (3) Might fungal hyphae be sufficiently resistant to justify considering Prototaxites to have had lichen affinities, as has been suggested by some (Selosse 2002;Retallack and Landing 2014)? ...
Premise of research. Although molecular analyses indicate that fungi likely began to diversify in the Proterozoic, fossil remains from this period have not been confidently linked to modern fungal lineages. Less ambiguous Early Paleozoic remains have been attributed to diverse modern fungal lineages, though some classifications have been questioned, and linking fragmentary fossils to modern fungal groups has generally been challenging. Better knowledge of fungal structures most likely to be preserved in the fossil record would aid classifying enigmatic remains. To achieve this, we tested a spectrum of modern fungi that have been linked to Paleozoic fossils and/or display environmental persistence for retention of diagnostic structural features after acetolysis, a high-temperature acid hydrolysis process employed as a proxy for harsh diagenetic processes. Methodology. Standard acetolysis was applied to cultures of blastocladialean, mucoralean, or ascomycete fungi having melanized structures hypothesized to resist hydrolytic degradation; glomalean fungi associated with greenhouse-grown and field-collected thalloid liverworts; and basidiocarp samples from two species of the woody basidiomycete Ganoderma. Pivotal results. Distinctive acetolysis-resistant fungal structures included Allomyces javanicus-resistant sporangia; glomalean hyphae and spores; tubular sporangiophores, globular asexual sporangia, zygosporangia with suspensors, and hyphal tangles of Phycomyces blakesleeanus (Mucoromycotina); conidiophores, phialides, chains of conidia, and cleistothecial walls of Aspergillus chevalieri (Ascomycota); and dense-walled septate hyphae and perithecia of Sordaria fimicola and Chaetomium globosum (Ascomycota). Several taxa left few (e.g., nondistinctive spores) or no identifiable cellular remains. Conclusions. Consistent with previous reports, melanized structures tended to be hydrolysis resistant. Retention by modern liverwort-associated glomalean fungi of diagnostic hyphal and spore features after acetolysis indicates high potential for fossilization even under suboptimal conditions, supporting a previous classification of microfossils extracted from Ordovician carbonates. Acetolysis results were also consistent with interpretation of particular Silurian-Devonian macrofossils as plant-microbial consortia.
... It has been considered a basidiomycete, possessing septal pores and unfused clamp connections (Hueber 2001), but no basidia were found. In order to sustain itself, these massive structures must have had a carbon source, and it has been suggested that came from green algae embedded in the thallus, and this would also explain some of the polymers found (Selosse 2002). An alternative subsequent interpretation was that it represented rolled-up mats of liverworts intermixed with fungal and cyanobacterial associates, but that hypothesis does not seem sustainable (Boyce and Hotton 2010). ...
Following a discussion on the naming of lichens and a definition of “lichen”, hypotheses on the origins of lichenization and lichen-forming fungi are reviewed. It is emphasized that lichen associations strictly have no scientific name, while the partners in the symbiosis do. As fungi have a wide range of associations with algae and cyanobacteria, the definition of “lichen” must include the fungal partner enclosing the photosynthetic, and the photosynthetic partner not being incorporated into fungal cells. Hypotheses put forward to explain lichenization are examined in the context of the evidence from the fossil record and molecular biology. There are uncertainties over the interpretation of many of the pre-Devonian fossils, but stratified undisputed lichen-like associations were present in the Lower Devonian, and material referable to modern genera is preserved in Eiocene and Miocene amber. Some early molecular studies suggested that the earliest ascomycetes may have been lichenized, but as more fungi have been sequenced, it has emerged as more likely that there have been repeated lichenization and de-lichenization events in different lineages over time. Some caution is necessary as the molecular trees do not included data from extinct lineages. The possibility that there were early lichen-like fungal associations as far back as the late Pre-Cambrian or early Cambrian cannot be discounted on the basis that they are not recognizable in the fossil record.
... Permineralized Prototaxites is known from fluvial facies (Boyce et al. 2007, Retallack & Landing 2014, but Mosellophyton is represented by carbonaceous compressions preserved in place of growth with marine fossils (brachiopods, tentaculites), in low-diversity assemblages comparable with those of modern salt marshes (Schaarschmidt 1974, Schultka & Remy 1990, Wehrmann et al. 2010. Although algal affinities have been proposed for nematophytes (Schweitzer 1983, Strother 1988, evidence from charcoalified (Edwards & Axe 2012;Edwards et al. 2013) and permineralized specimens (Hueber 2001, Retallack & Landing 2014 and from stable isotopic studies (Boyce et al. 2007, Hobbie & Boyce 2010) now indicates that nematophtyes were terrestrial lichens (Retallack 1994, Selosse 2002, Edwards et al. 2013, Retallack & Landing 2014. Unlike Devonian to modern ascolichens and basidiolichens (Honegger et al. 2013a, b), nematophytes may have been a symbiosis of glomeromycotan fungi and green algae (Retallack & Landing 2014). ...
Retallack, G.J., 1.7.2015. Reassessment of the Silurian problematicum Rutgersella as another post-Ediacaran vendobiont. Alcheringa 39, 573–588. ISSN 0311-5518 Rutgersella is a problematic fossil from the early Silurian (Llandovery) Shawangunk Formation of New Jersey, at first interpreted as a jellyfish comparable with Ediacaran fossils, such as Dickinsonia. Three proposed species of Rutgersella from the same locality are here regarded as growth or reproductive variants of a single species, R. truexi. Sedimentary structures, associated trace fossils and petrographic examination now show that they were sessile organisms of intertidal mudflats. These fossils have been dismissed as pyrite suns, but thin-sections show that they were weakly pyritized, organic structures, with a quilted hollow internal structure, similar to Seilacher’s constructional and taxonomic concept of Vendobionta. As for Cambrian Swartpuntia, and Devonian Protonympha, Rutgersella may be a post-Ediacaran vendobiont. The biological affinities of Rutgersella are problematic, but are compared with coenocytic green algae, cellular slime moulds, puffball-like fungal fruiting bodies and foliose lichens. Gregory J. Retallack [[email protected]
/* */], Department of Geological Sciences, University of Oregon, Eugene, OR 97403-1272, USA.
... As Marc-Andr e Selosse (Mus eum national d'Histoire Naturelle, Paris, France) and Dianne Edwards (University of Cardiff, UK) discussed, the affinities of the enigmatic Nematophytalesan extinct group that includes the gigantic Prototaxites, a widespread Devonian columnar organism, which could reach up to 9 m in height and 1 m in diameterare still debated . A fungal affinity is suspected because of their distinctive filamentous organization, but since the contemporary plant biomass was likely insufficient to support large heterotrophs, it has been suggested that Nematophytales had photosynthetic abilities , or even a lichen-like nature (Selosse, 2002). Although remains of photobionts are still controversial, recent research bears out the lichenized nature of the much smaller thalloid forms Honegger et al., 2013). ...
... Although Nematasketum is well preserved as a charcoalification and has been examined by SEM, the affinities of this organism are still equivocal. Prototaxites and Nematasketum, as well as some other enigmatic thalloid organisms from the Silurian and Devonian known as nematophytes, may represent fungi, some type of symbiotic association such as lichens (Selosse 2002), or life forms that have no modern analogues. At present, these interesting fossils continue to defy attempts to place them within a modern systematic framework ). ...
Although there have been scattered reports of fossil fungi and funguslike organisms for more than 150 years, fungi have been largely ignored when interpreting the complexity and functioning of terrestrial paleoecosystems. To a large degree this is because fungi were long thought to be too delicate to be sufficiently preserved, and those who might discover them demonstrated insufficient interest and did not possess the appropriate training. Some of the methods traditionally used in the study of fossils have also contributed to a lack of recognition of the diversity of fungi in the fossil record. Today the importance of fungi as major constituents of ecosystem function is a primary focus of mycology. As a result, there has been a paradigm shift in the appreciation of the fungal world in time and space, including fungal diversity in ancient ecosystems. This chapter includes examples of fossil fungi from each of the major lineages and describes our current level of information about their morphology, biology, and evolution. It also provides some directions for future studies of fossil fungi and identifies some questions that only the fossil record can answer.
... As Marc-Andr e Selosse (Mus eum national d'Histoire Naturelle, Paris, France) and Dianne Edwards (University of Cardiff, UK) discussed, the affinities of the enigmatic Nematophytalesan extinct group that includes the gigantic Prototaxites, a widespread Devonian columnar organism, which could reach up to 9 m in height and 1 m in diameterare still debated . A fungal affinity is suspected because of their distinctive filamentous organization, but since the contemporary plant biomass was likely insufficient to support large heterotrophs, it has been suggested that Nematophytales had photosynthetic abilities , or even a lichen-like nature (Selosse, 2002). Although remains of photobionts are still controversial, recent research bears out the lichenized nature of the much smaller thalloid forms Honegger et al., 2013). ...
Thin sections of petrified fossils made during the latter part of the nineteenth and early twentieth centuries to investigate the internal tissue systems of plants now provide an important new source of information on associated microorganisms. We report a new heterokont eukaryote (Combresomyces williamsonii sp. nov.) based on exquisitely preserved fossil oogonia, antheridia and hyphae from the Carboniferous (Pennsylvanian: Bashkirian stage) of UK. The structure of the oogonia and antheridia and features observed within the hyphae demonstrate a relationship with Oomycetes (Peronosporomycetes). The fossil microorganism was documented in situ in petrified stem cortex and rootlets of the extinct seed fern Lyginopteris oldhamia (Pteridospermales). The main observed features point towards a pythiaceous Oomycete but links to biotrophic Albuginales or Peronosporaceae cannot be ruled out owing to the observation of a possible haustorium. Our study provides the earliest evidence for parasitism in Oomycetes.
... Diese Nennung beruht auf dem Vorkommen von sehr breiten und mehrere Dezimeter langen, sich verzweigenden Achsen, die auch von uns aufgesammelt werden konnten. Mittlerweile wurde Prototaxites anhand anatomisch erhaltener Exemplare aus Kanada neu beschrieben und in die Verwandtschaft der Pilze (Hueber 2001) oder Flechten (Selosse 2002) gestellt. Modelle, die auch von Schmidt (1958) im Zusammenhang mit Pachytheca diskutiert aber letztlich verworfen wurden. ...
A eurypterid from Early Siegenian strata near Betzdorf/Sieg is described and figured. This specimen is the first unequivocal record of the family Erieopteridae from the Siegenian of the Siegerland. The associated biota is briefly discussed and comprises trigonotarbid arachnids and the myriapod Eoarthropleura. This first record of landdwelling trigonotarbids and probably amphibious myriapods in the Siegen-Anticline is of palaeoecological significance as it documents the proximity of the depositional setting to former subaerially exposed areas.
... This may represent an early example of fungivory in the terrestrial fossil record, assuming that identification as a basidiomycete fungus is correct, based on micromorphological (Hueber, 2001) and isotopic (Boyce et al., 2007) data. Alternatively, the possibility remains that Prototaxites represents a lichen-like mutualism (Selosse, 2002), an extinct lineage with no modern taxonomic counterpart (Taylor et al., 2009), or more remotely, a liverwort (Graham et al., 2010). ...
To test the extent of herbivory in early terrestrial ecosystems, we examined compression–impression specimens of the late M iddle D evonian liverwort M etzgeriothallus sharonae , from the C atskill D elta deposit of eastern N ew Y ork state.
Shale fragments of field‐collected specimens were processed by applying liquid nitrocellulose on exposed surfaces. After drying, the film coatings were lifted off and mounted on microscope slides for photography. Unprocessed fragments were photographed under cedarwood oil for enhanced contrast.
An extensive repertoire of arthropodan‐mediated herbivory was documented, representing three functional feeding groups and nine subordinate plant–arthropod damage types ( DT s). The herbivory is the earliest occurrence of external foliage‐feeding and galling in the terrestrial fossil record. Our evidence indicates that thallus oil body cells, similar to the terpenoid‐containing oil bodies of modern liverworts, were probably involved in the chemical defence of M . sharonae against arthropod herbivores.
Based on damage patterns of terrestrial plants and an accompanying but sparse body‐fossil record, D evonian arthropodan herbivores were significantly smaller compared to those of the later P alaeozoic. These data collectively suggest that a broad spectrum herbivory may have had a more important role in early terrestrial ecosystems than previously thought.
... LICHENS are complex organisms involving a symbiotic relationship between a photobiont (a green alga or a cyanobacterium or both) and a mycobiont (a fungus), and have attracted considerable attention because of their perceived position on the ladder of evolution to land plants 1,2 . The carbohydrate needs of the fungus are met by the photobiont through photosynthesis, and the fungus, in turn, helps extend the ecological and geographical range of the photobiont, besides providing protection and increasing access to nutrients and water. ...
Phyllosphere - the world on a leaf, contains an interesting symbiotic association of a photobiont and a mycobiont, called foliicolous lichens. These are widely distributed in wet or moist, highly humid or foggy tropical and subtropical forests, on leaf surfaces of plants called phorophytes and are characterized by low endemism and short life cycle, corresponding to the leaf lifespan. Species diversity of foliicolous lichens is remarkable, with a single phorophyte individual supporting 65-84, and a single leaf as many as 81 lichen species. They exhibit marked structural diversity and ecomorphological adaptations to light conditions, and are potentially sound indicators of environmental conditions. In India, so far only 116 species of these lichens have been recorded, mainly from the Andaman and Nicobar Islands, Palni and Nilgiri Hills, and the Northeast. This article highlights conspicuous lack of information on the ecology and life history of these interesting organisms.
... However, there are numerous microbial, fungal and lichen fossils with structures, shapes and anatomies unknown among extant taxa, many of them being poorly preserved; examples are the extensive microbial crusts which covered Australian palaeosols in the Mid Cambrian (Retallack, 2011). Did fungi ever form stems of several metres height or length, as postulated for the enigmatic, Early Devonian Prototaxites (Hueber, 2001;Selosse, 2002)? If so, what was their C source: detritus or photosynthates derived from photoautotrophic symbionts? ...
Lichenization is assumed to be a very ancient mode of fungal nutrition, but fossil records are rare. Here we describe two fragments of exceptionally preserved, probably charred, lichen thalli with internal stratification. Cyanolichenomycites devonicus has a cyanobacterial and Chlorolichenomycites salopensis a unicellular, presumably green algal photobiont. Fruiting bodies are missing. Cyanolichenomycites devonicus forms asexual spores in a pycnidium.
All specimens were examined with scanning electron microscopy techniques. The fossils were extracted by maceration. Extant lichens and free‐living cyanobacteria were either experimentally charcoalified for comparison or conventionally prepared.
Based on their septate hyphal structure, both specimens are tentatively interpreted as representatives of the Pezizomycotina (Ascomycota). Their presence in 415 million yr (Myr) old rocks from the Welsh Borderland predates existing Late Cretaceous records of pycnidial conidiomata by some 325 Myr and Triassic records of lichens with broadly similar organization by some 195 Myr.
These fossils represent the oldest known record of lichens with symbionts and anatomy as typically found in morphologically advanced taxa today. The latter does not apply to Winfrenatia reticulata , the enigmatic crustose lichen fossil from the Lower Devonian, nor to presumed lichen‐like organisms such as the Cambrian Farghera robusta or to the Lower Devonian Spongiophyton minutissimum .
... It is clearly one of the most important types of symbiosis involving ascomycetes, where over 40% of the known species are lichenized (Kirk et al ., 2001). This mutualistic lifestyle has also been suggested as a possible way for the colonization of land in the course of evolution (Heckman et al ., 2001;Selosse, 2002). Not until recently, however, have the major patterns of lichen evolution become better understood (Gargas et al ., 1995;Lutzoni et al ., 2001;Wiklund & Wedin, 2003;Lumbsch et al ., 2004), and although most researchers agree that lichenization has evolved many times in the phylogeny of fungi, it has also been suggested that many non-lichenized ascomycete groups have lost the symbiotic connection with algae secondarily (Lutzoni et al ., 2001). ...
Summary • Lichenization is one of the most important fungal lifestyles and lichen fungi are assumed to form obligate symbioses with their photobionts. Here we test if lichenized and non-lichenized samples in three cases of closely related lichenized Conotrema and saprotrophic Stictis (Stictidaceae, Ostropales, Ascomycota) in northern Scandinavia, form distinct monophyletic groups (= species). • We applied phylogenetic species recognition, by analysing fungal DNA sequence data from four independent genomic markers. • Separate parsimony and parsimony jack-knifing analyses of three independent genes are congruent and result in intermixed groups of lichenized and saprotrophic specimens. The sequence variation in an intron also supports this. Our results suggest that all three cases represent independent fungal phylogenetic species, which can undergo their whole sexual lifecycle either as lichens or as saprotrophs. • The use of different nutritional modes – optional lichenization – allows separate individuals to exploit different niches during the forest succession. We suggest that this environmental plasticity may be common in the Stictidaceae, and propose that it is an overlooked strategy in fungi adapted to unpredictable successional ecosystems. New Phytologist (2004) doi: 10.1111/j.1469-8137.2004.01198.x ©New Phytologist (2004)
... Th ese fossils are now being reinterpreted, following developments in chemical analysis that suggest that their walls were not composed of the sorts of chemicals you would expect in plant cell walls. As a result, it has been claimed that some of the nematophytes (including Prototaxites) were terrestrial fungi or lichens, creating the possibility that the earliest terrestrial organisms were fungal, some being far larger than any known today (Gray, 1985;Wellman, 1995;Selosse and Le Tacon, 1998;Wellman and Gray, 2000;Hueber, 2001;Selosse, 2002;Southwood, 2003). ...
Research done over the last century has persistently indicated major diff erences between fungi, animals, and plants. Unfortunately, for most of that time fungi have been considered, quite errone-ously, to be closely related to plants; as observations have been constrained to comply with this funda-mental error, a proper appreciation of fungal developmental biology has been seriously inhibited. During the fi nal quarter of the 20t century, the phylogenetic status of the true fungi as an independent Kingdom of eukaryotes became clear. In this review, I bring together some of the observations, old and recent, that contribute to our current understanding of the way that fungi construct multicellular structures.
... It is especially difficult to envisage a heterotrophic organism the size of Prototaxites (some " trunks " reached more than 1 m in diameter) existing in a terrestrial environment inhabited by a relatively sparse vegetation consisting of land plants only several centimeters tall. Rather, Prototaxites may represent an example of an ancient mutualistic association that combined both heterotrophy and some level of the lichen-like nutritional mode (Selosse, 2002). It may be that cyanobacteria and/or chlorophytes inhabited the distal and outer parts of the organism and have simply not been found, or not recognized. ...
Microorganisms are critical in the bio-and geosphere today, and certainly performed similar functions in ancient ecosystems. Bacteria, cyanobacteria, microalgae, and various fungi and fungi-like organisms constitute a substantial component of these ancient communities, and have been responsible for the evolution and sustainability of the ecosystems in functions ranging from decomposition of metabolites to catalyzation of nutrient cycles. This review provides examples of associations and interactions between microorganisms and land plants, principally from the Devonian and Carboniferous. During this time span of approximately 150 myr, most of the vascular plant lineages evolved and radiated into new terrestrial niches. Several exceptionally well-preserved fossil communities are used to demonstrate a wide range of biological interactions. Although none of the land plant partners exist today, many of the microorganisms involved appear morphologically little changed. Moreover, some interactions suggest that the genetic code and biochemical pathways necessary for the associations and interactions to be successful evolved early in the lineages of microorganisms involved, and have seemingly remained unchanged to the present. The examination of microorganism/land plant associations (and interactions) provides another level of biological resolution that can be used to track coevolutionary processes and help formulate hypotheses designed to more fully understand the evolutionary history of ecosystems.
... Taking an analogous approach to the sporocarp hypothesis, we point out that 8.8 m tall basidomycete sporocarps (or any even near that size) are not known to exist on Earth now, raising reasonable doubt that such occurred in the past. An equivalent challenge to advocates of the fungal sporocarp hypothesis might be to genetically alter a modern basidiomycete fungus so that it can produce cylindrical fruiting bodies at least 8.8 m tall and over a meter in diameter, then demonstrate that the sporocarps (lacking wood) can remain upright in windstorms, subject the sporocarps to experimental taphonomic studies to evaluate the extent to which internal anatomy resists degradation and refl ects Prototaxites anatomy, and show why reproductive traits predicted by the sporocarp hypothesis are not readily observed in the fossils ( Selosse, 2002 ). We suggest an alternative method for evaluating the rolled mat hypothesis. ...
New structural, nutritional, and stable carbon isotope data may resolve a long-standing mystery-the biological affinities of the fossil Prototaxites, the largest organism on land during the Late Silurian to Late Devonian (420-370 Ma). The tree trunk-shaped specimens, of varying dimensions but consistent tubular anatomy, first formed prior to vascular plant dominance. Hence, Prototaxites has been proposed to represent giant algae, fungi, or lichens, despite incompatible biochemical and anatomical observations. Our comparative analyses instead indicate that Prototaxites formed from partially degraded, wind-, gravity-, or water-rolled mats of mixotrophic liverworts having fungal and cyanobacterial associates, much like the modern liverwort genus Marchantia. We propose that the fossil body is largely derived from abundant, highly degradation-resistant, tubular rhizoids of marchantioid liverworts, intermixed with tubular microbial elements. Our concept explains previously puzzling fossil features and is consistent with evidence for liverworts and microbial associates in Ordovician-Devonian deposits, extensive ancient and modern marchantioid mats, and modern associations of liverworts with cyanobacteria and diverse types of fungi. Our interpretation indicates that liverworts were important components of Devonian ecosystems, that some macrofossils and microfossils previously attributed to "nematophytes" actually represent remains of ancient liverworts, and that mixotrophy and microbial associations were features of early land plants.
... Equally popular is the statement that AMF, that is the Glomeromycota, have co-evolved with plants for at least the last 400 million yr, and that this association allowed the conquest of dry terrestrial ecosystems by Embryophyta (Selosse & Le Tacon, 1998;. Recent reanalyses of early enigmatic terrestrial fossils suggest that the first macroscopic land colonizers were fungal-algal associations, such as Prototaxites (Selosse, 2002) or Spongiophyton (Taylor et al., 2004). Indeed, adding an alga (which is able to exploit light and CO 2 from the environment) to a fungus (able to exploit the soil substratum) makes a perfect adaptation to living at the soil-atmosphere interface, the landmark of land plants. ...
Meeting - 22nd New Phytologist Symposium: Effectors in plant–microbe interactions, INRA Versailles, France, September 2009
This ISPRA book, entitled “Micological biodiversity and its knowledge.
Mushrooms between innovation and tradition ", allow readers to start a journey of knowledge in the world of mushrooms. It intends to be a popularizing tool to solicit basic knowledge and to deepen and suggest a correct and responsible relationship with the environment and with all of its component.
The work includes a general part concerning the groups that make up the Kingdom of Mushrooms, with description of the different shapes, colors, sizes and toxicity, to then deal with the topic of biodiversity.
It ends with a part on Mushrooms and Institutions. The chapters are also accompanied by in-depth boxes that touch on problems of basic, of a technical-methodological, environmental and biotechnological nature.
Devonian evolution of woodlands has been envisaged as a protracted increase in size of vascular plants, which can be reconstructed from fossil stumps and trunks. However, Late Silurian and Early Devonian nematophytes such as Prototaxites would have towered over land plants, including vascular plant trees, in the same fossil plant assemblage, until finally overtaken by vascular land plants during the Early Carboniferous. Nematophytes lack tissues of vascular plants, and some have spherical photobionts encircled and indented by hyphae, as in lichens. Nematophytes were not monolithic poles, but branched, and trunk spacing in paleosols is evidence that they formed closed canopies. Depths of root and hyphal bioturbation and pedogenic calcite precipitation in paleosols though time increase with greater height of trees. In addition to large non-vascular trunks and early land plants in Ordovician to Devonian paleosols, there also were extensive, nutrient-gathering, networks of glomeromycotan mycorrhizae. An Ordovician-Silurian “age of lichens”, when nematophytes were the tallest elements of terrestrial vegetation and soils were riddled with mycorrhizae, may have nurtured and sheltered Devonian woody plants. Fungi preceded and facilitated the evolution of early land plants.
In diesem Buch beschäftigt sich Ludmila Lysenko mit der Frage, ob es sich bei Subulicystidium longisporum um eine kryptische Spezies handelt. Die Autorin untersucht hierzu erstmals Proben mit einer breiten geographischen Abdeckung unter Verwendung diverser phylogenetischer Analyseverfahren auf ihre Sequenzunterschiede im Locus ITS. Zur Unterstützung der molekulargenetischen Daten wird die Form und Größe der Basidiosporen hinzugezogen.
Der Inhalt
• Die kryptische Spezies Subulicystidium longisporum
• ITS (internal transcribed spacer) als molekulargenetisches Tool im Reich der Fungi
• DNA-Barcoding im Reich der Fungi
• Schwierigkeiten der morphologischen Artabgrenzung
• Vor- und Nachteile der molekulargenetischen Untersuchung zur Speziesidentifizierung
Die Zielgruppen
• Dozierende und Studierende der Mykologie, Biologie und Molekularbiologie
• Fachkräfte aus den Bereichen Mikrobiologie und Labordiagnostik
Die Autorin
Ludmila Lysenko studierte Biologie an der Universität Kassel, ihr Forschungsschwerpunkt ist die Biodiversität. Sie verfügt über Kenntnisse der klassischen Artbestimmung basierend auf morphologischen Merkmalen als auch durch diverse molekulargenetische Untersuchungsmethoden. Sie beschäftigte sich in ihren Arbeiten aus dem Fachbereich Ökologie intensiv mit Arten der corticioiden Basidiomycota.
Land phototrophs need to exploit both atmosphere (providing gas and light) and substrate (furnishing water and minerals). Yet, their algal ancestors were poorly pre-adapted to such a life at the interface. We review the paleontological evidence that fungal symbioses which can exploit substrate resources, helped adaptation to land constraints. Diverse structures dating back to the Devonian present convincing evidence for lichens, (symbioses between fungi and microscopic algae) but fossils remain scarce, so that early lichen abundance and ecological relevance remain questionable. Several enigmatic but abundant fossils from the Siluro-Devonian, such as Spongiophytonor the giant Prototaxites (Nematophytes), likely represent fungus-algal symbioses, which shaped early terrestrial ecosystems. Yet, these taxa are fully extinct, and do not have clear affinities with extant groups. Finally, terrestrialization of Embryophyta (land plants), which currently dominate land ecosystems, is linked to a symbiosis with Glomeromycetes. Today, these fungi form arbuscular mycorrhizae, which help most Embryophyta to exploit soil, and molecular data combined with paleontological evidence support the idea that this type of association is ancestral. The role of symbiotic Mucoromycetes during terrestrialization is not fully understood and mycorrhizal association diversified later in the evolution of Embryophyta. Fungal-algal symbioses thus recurrently contributed to terrestrialization of phototrophs.
Recent progress in the palaeomycological studies are presented in this review. The span of geologic time extending from the Precambrian examined for many sources of information in relation to major taxonomic groups of fungi. The complexity of the fungus-host interactions during the geological times suggests the most modem groups should extend well back to Precambrian. Both the fossil record and molecular sequences data suggest that the Glomeromycota and Ascomycota are older than previously thought. The fungal-plant root associates known as a mycorrhizal symbiosis appear to have evolved in the Early Devonian. The distribution of fungi in, space and time based on fossil evidence, together with rapidly accumulating molecular data, will provide the continuing impetus to characterize more accurately the phylogeny on the fungi.
The impacts of molecular approaches on fungal systematics are considered with respect to the elucidation of major evolutionary lineages, convergence and divergence of characters, generic concepts (including pleomorphism), species concepts (including cryptic species), the development of identification methods, and issues arising from the discovery of unattributable environmental sequences. The importance of collaborations between morphosystematists and molecular biologists is emphasized, including in the development of nomenclatural systems. Attention is drawn to caveats meriting consideration when undertaking molecular systematic studies. References to examples from the primary and recent literature are included throughout.
This book provides up-to-date coverage of fossil plants from Precambrian life to flowering plants, including fungi and algae. It begins with a discussion of geologic time, how organisms are preserved in the rock record, and how organisms are studied and interpreted and takes the student through all the relevant uses and interpretations of fossil plant. With new chapters on additional flowering plant families, paleoecology and the structure of ancient plant communities, fossil plants as proxy records for paleoclimate, new methodologies used in phylogenetic reconstruction and the addition of new fossil plant discoveries since 1993, this book provides the most comprehensive account of the geologic history and evolution of microbes, algae, fungi, and plants through time. * Major revision of a 1993 classic reference * Lavishly illustrated with 1800 images and user friendly for use by paleobotanists, biologists, geologists and other related scientists * Includes an expanded glossary with an extensive up-to-date bibliography and a comprehensive index * Provides extensive coverage of fungi and other microbes, and major groups of land plants both living and extinct.
The Ordovician and Silurian periods were times of major geological activity as regards palaeogeography, volcanism and climate change, the last of these evidenced by a series of cooling episodes and glaciations that climaxed in the Hirnantian (Late Ordovician). The presence of cryptospores in the Darriwilian (Middle Ordovician) marked the advent of higher plants on land. A critical survey of direct (mega- and microfossils) and some indirect evidence in succeeding rocks indicates the presence of algae, Bacteria, Cyanobacteria, Fungi, probable lichens, cryptophytes and basal tracheophytes. Similar associations of photosynthesizers and decomposers occur today in cryptogamic covers (CCs), for example biological crusts, except that bryophytes replace cryptophytes (basal embryophytes) and tracheophytes are absent. Thus, extant CCs, which make significant contributions today to global carbon and nitrogen fixation and prevention of erosion, provide an excellent analogue for the impacts of early land vegetation on both lithosphere and atmosphere. As a prerequisite to assessing impacts in Ordovician–Silurian times, with particular consideration of parameters used by climate modellers, the effects of a number of abiotic factors on the growth and survival of extant cryptogamic ground covers and their environmental impacts are reviewed. Factors include photosynthetically active radiation, ultraviolet radiation, temperature, water, oxygen, carbon dioxide, nitrogen, phosphorus, iron, surface roughness and albedo. A survey of the nature and extent of weathering facilitated by such vegetation concludes that it was limited based on depth of weathering when compared with that from rooted tracheophytes today, with minor effects on carbon dioxide drawdown. As global net productivity from Ordovician–Silurian CCs was very probably lower than today, and while the small fraction of intractable material in their organic carbon would have resulted in a more rapid turnover of terrestrial biomass, we conclude that there was decreased possibility of long-term organic carbon burial. Hence, there would have been very limited increase in atmospheric oxygen and decrease in carbon dioxide resulting from carbon burial.
В работе излагаются основы теоретической морфологии высших грибов. Рассмотрена проблема конвергенции в морфогении споро-ношений. Представлена система морфотипов высших грибов, наме-чены области ее приложения. Книга представляет интерес для специалистов, интересующихся проблемой конвергенции низших эвкариотных организмов.
В работе излагаются основы теоретической морфологии высших грибов. Рассмотрена проблема конвергенции в морфогении спороношений. Представлена система морфотипов высших грибов, намечены области ее приложения. Книга представляет интерес для специалистов, интересующихся проблемой конвергенции низших эвкариотных организмов.
An enigmatic thallophyte (Litothallus ganovex gen. et sp. nov.) occurs in the form of compressions with
cellular preservation and associated sheets of complete cells in non-marine Triassic deposits in the
Transantarctic Mountains, Antarctica. A combination of microscopic techniques (i.e. bright field and
epifluorescence microscopy, SEM) was used to document details of this organism. The thalli are flat and
appear to be composed of one to several congruently superimposed cell sheets that together form a
plectenchyma or pseudoparenchyma. This discovery represents the youngest record of sheets of fossil cells, which have heretofore exclusively been reported from the Proterozoic and Palaeozoic, and is one of the few examples of cell sheets that can be attributed to macroscopic remains with confidence. We interpret the thalloid organism from Antarctica as the remains of a crustose freshwater macroalga based on its occurrence in overbank deposits of a braided fluvial environment and its morphological similarity to thalli of extant freshwater representatives of the red algal order Hildenbrandiales.
Fungal symbioses are one of the key attributes of land plants. The twenty first century has witnessed the increasing use of molecular data complemented by cytological studies in understanding the nature of bryophyte-fungal associations and unravelling the early evolution of fungal symbioses at the foot of the land plant tree. Isolation and resynthesis experiments have shed considerable light on host ranges and very recently have produced an incisive insight into functional relationships. Fungi with distinctive cytology embracing short-lived intracellular fungal lumps, intercellular hyphae and thick-walled spores in Treubia and Haplomitrium are currently being identified as belonging to a more ancient group of fungi than the glomeromycetes, previously assumed to be the most primitive fungi forming symbioses with land plants. Glomeromycetes, like those in lower tracheophytes, are widespread in complex and simple thalloid liverworts. Limited molecular identification of these as belonging to the derived clade Glomus Group A has led to the suggestion of host swapping from tracheophytes. Ascomycetes, all identified to date as Rhizoscyphus ericae and having an extremely wide host range extending into the Ericales, occur in the rhizoids of a range of leafy liverwort families that are sister to the Schistochilaceae, where the fungus induces rhizoid branching and septation. Dating of the Schistochilaceae suggests that these liverwort rhizoid associations predated ericoid mycorrhizas. A more restricted distribution of basidiomycetes, all identified as members of the genus Sebacina, is interpreted as a secondary acquisition in leafy liverworts following the loss of ascomycetes. Unlike the latter and ectomycorrhizal basidiomycetes in tracheophytes, these are host specific. Whereas there is no evidence of host digestion for either the ascomycetes or basidiomycetes in leafy liverworts, basidiomycetes in the Aneuraceae display regular colonization and digestion cycles. Considerable molecular diversity in the aneuracean fungi, mainly in the genus Tulasnella with occasional sebacinoids, mirrors the same in the host liverworts. Nesting of the only mycoheterotrophic liverwort Cryptothallus within Aneura is congruent with the phylogeny of the endophytes. Glomeromycete fungi have been identified in Phaeoceros and Anthoceros whereas Dendroceros, Megaceros and Nothoceros lack endophytes but the distribution of fungi across hornworts has yet to be explored. In contrast to liverworts and hornworts, there is no evidence of mycorrhiza-like associations in mosses. Claims that the fossil Prototaxites was a fossil fungus-associated liverwort are discounted.
Trees do not form a natural group but share attributes such as great size, longevity, and high reproductive output that affect their mode and tempo of evolution. In particular, trees are unique in that they maintain high levels of diversity while accumulating new mutations only slowly. They are also capable of rapid local adaptation and can evolve quickly from nontree ancestors, but most existing tree lineages typically experience low speciation and extinction rates. We discuss why the tree growth habit should lead to these seemingly paradoxical features.
Ascomycetes are the largest group of true fungi, and characteristically
produce their sexual spores in a sac-like structure called the ascus.
They include medicinal agents (such as ergot), plant pathogens (Dutch
elm disease is caused by an ascomycete) and yeasts used in fermentation.
We have found the oldest ascomycetous fungi with flask-shaped ascocarps
in thin-section preparations of the Lower Devonian (400 million years
old) Rhynie chert of Aberdeenshire, Scotland. This discovery has
implications for dating the origin of this group of fungi, and
underscores the diversity of fungal-plant interactions early in the
colonization of the land.
Spores of twenty species of Spirogyra were treated by acetolysis and viewed by scanning electron microscopy. The terms exo-, meso- and endospore should be maintained and based on chemical composition. Exo- and endospore are cellulose and/or pectin containing membranes. The mesospore is acetolysis-resistant and presumably contains sporopollenin.As basic pattern the spore wall in Spirogyra is composed of four layers: one exo- and endospore layer and two mesospore layers. The outer mesospore layer is mostly thin and hyaline, the inner layer thick and brown or yellow coloured and often sculptured. The germination suture is located in the inner mesospore layer. Some variations on this basic pattern were observed in Spirogyra bellis, S. cleveana and S. majuscula. Details of mesospore sculpture were observed and some taxonomic implications are discussed.The observed basic pattern is assumed to be valid for the Zygnemataceae as a whole.
The Devonian flora discovered and collected by W.E. Logan in 1843 remained unstudied until 1855 at which time the collections were offered to J.W. Dawson. His attention was immediately drawn to a single large specimen in the collections, which he identified and described as partially rotted wood of a conifer (Dawson, 1857). He proposed the name Prototaxites (Dawson, 1859) thereby expressing his concept of the genus. That concept remained unchallenged until Carruthers (1872) heatedly ridiculed both the name and the author and illegitimately substituted the name Nematophycus. His subjective opinion was that the fossil represented a fragment of a very large alga, like Lessonia. His classification, challenged only once (Church, 1919), persisted in all subsequent reports. Dawson remained adamant in his definition of Prototaxites until he illegitimately substituted the name Nematophyton for Prototaxites (Dawson, 1888) and denied (Dawson, in Penhallow, 1889) that he had ever classed the genus with the conifers. The names Nematophycus and Nematophyton are later synonyms of Prototaxites and, although inappropriate in connotation, Prototaxites is nomenclaturally valid. No undoubted original nor associated specimens are available for choice of a lectotype. This report has a triple purpose: (1) to name, as neotype, a recognizable specimen collected by Dawson for which the locality and stratigraphic data are known, (2) to redescribe the genus as structurally composed of three interactive forms of hyphae, i.e. large thin-walled, septate, branching, generative hyphae; large thick-walled, non-septate, skeletal hyphae; and small thin-walled, septate, branching, binding hyphae, which combine to form a gigantic, phototropic, amphigenous, perennial sporophore with saprobic nutrition, and (3) to classify it in the Kingdom Fungi. Generic synonymy with Prototaxites is proposed for Nematophycus (Carruthers, 1872).
In 1843–44, Sir W. E. Logan ascertained, and published in his Report* for the latter year, the occurrence of a series of beds of Devonian age in the Peninsula of Gaspé, Lower Canada, containing fossil plants, apparently of terrestrial origin, and some of them evidently in situ. Nothing was done toward the precise determination and description of these remains until 1856, when Sir William kindly permitted the writer of this paper to examine his collection, and to describe before the American Association for the Advancement of Science the most interesting specimen contained in it—a fossil trunk exhibiting a very remarkable and previously undescribed coniferous structure†. The other specimens in the collection were so fragmentary or obscure, that it was not deemed expedient to attempt their description before studying them (as all fossil plants should, when practicable, be studied) in the rocks in which they occur. With this view I visited Gaspé in the past summer, and examined the localities indicated on the plans and sections of the Geological Survey. The facts and specimens thus obtained will probably be fully described and illustrated in one of the forthcoming Decades of Canadian Fossils; and in the meantime I propose to notice some of the species observed, which appear to be of especial interest in the present state of our general knowledge of the Devonian flora.
Before proceeding to these descriptions, it may be necessary to state that the deposit in which the fossils occur consists of sandstone and shale, of various colours
Silicified and carbonized axes of Prototaxites are chemically analyzed by means of X-ray and organic-extraction techniques. The isolation and identification of cutin and suberin derivatives, i.e., ω-hydroxymonocarboxylic acids, suggest that Prototaxites may have been a terrestrial plant or an aquatic plant showing chemical adaptation to periods of desiccation. Normal saturated acids showing no odd or even carbon-number predominance, phenyl and naphthyl aromatic acids, and normal and aromatic dicarboxylic acids isolated from fossil material, are considered inconsistent with an algal biochemistry. The normal saturated fatty acids isolated from Parka, Pachytheca, Spongiophyton, Protosalvinia, Orestovia and Taeniocrada are compared with Prototaxites. Parka, Pachytheca, Spongiophyton and Orestovia, parallel one another in their organic chemical constituents, while Protosalvinia, Taeniocrada and Prototaxites appear to have paralleled one another in their adaptation to a terrestrial habit.
The foliage of Pinus strobus (eastern white pine), as that of all other conifers examined, is occupied by endophytic fungi, the most frequent of which is Lophodermium nitens. The number and extent of endophytic infections and the genetic relationship of individual isolates within living needles as well as their relationship to isolates from forest floor needles is unknown. To examine these and related questions, forest floor isolates and foliar endophytes from needle segments were obtained for ribosomal DNA sequencing and randomly amplified polymorphic DNA (RAPD) analysis. Molecular and morphological data were compared and infection frequency determined as a function of position along the needle. Ribosomal DNA sequences of foliar and ascospore isolates showed high levels of genetic similarity ( 97 % identity) for the internal transcribed spacer region. RAPD profiles were able to distinguish ascospore siblings from non-siblings, and also revealed that many needle isolates belonged to the same genotype as adjacent neighbour isolates, as would be expected from mycelial spread within the needle. Morphotype evaluation and RAPD profiles showed similar patterns : identical morphotypes grouped together and showed little or no genetic difference under RAPD analysis. Both morphological and molecular data indicated that the majority of infections were contained within 1 mm needle segments but could extend to about 4 mm in length. Infection frequency increased along the length of the needle from the proximal (shoot) end to the distal tip, with markedly higher rates in the distal quarter. Thus, endophytic infections of L. nitens in white pine needles consist of many localized, discrete infections, originating from ascospores and differentially distributed along the length of the needle. In the course of this work, it was found that GenBank accession no. AF203470 under the name Meloderma desmaszieresii appeared not to be that species but L. nitens on the basis of the ITS sequences.
Numerous mutualistic associations between phototrophs and fungi exist in the extant land biota. Some are widespread, such as lichens and mycorrhizae, but some are less well known or restricted to special ecological conditions, such as endophytes in plants and algae. Recent molecular data and fossils suggest that associations arose repeatedly and that some of them are ancient, and even ancestral in the case of land plants. Mutualism, that provides various adaptations to terrestrial constraints, may have played a crucial role during terrestrialization and evolution of land phototrophs.
Dispersed microfossils (spores and phytodebris) provide the earliest evidence for land plants. They are first reported from the Llanvirn (Mid-Ordovician). More or less identical assemblages occur from the Llanvirn (Mid-Ordovician) to the late Llandovery (Early Silurian), suggesting a period of relative stasis some 40 Myr in duration. Various lines of evidence suggest that these early dispersed microfossils derive from parent plants that were bryophyte-like if not in fact bryophytes. In the late Llandovery (late Early Silurian) there was a major change in the nature of dispersed spore assemblages as the separated products of dyads (hilate monads) and tetrads (trilete spores) became relatively abundant. The inception of trilete spores probably represents the appearance of vascular plants or their immediate progenitors. A little later in time, in the Wenlock (early Late Silurian), the earliest unequivocal land plant megafossils occur. They are represented by rhyniophytoids. It is only from the Late Silurian onwards that the microfossil/ megafossil record can be integrated and utilized in interpretation of the flora. Dispersed microfossils are preserved in vast numbers, in a variety of environments, and have a reasonable spatial and temporal fossil record. The fossil record of plant megafossils by comparison is poor and biased, with only a dozen or so known pre-Devonian assemblages. In this paper, the early land plant microfossil record, and its interpretation, are reviewed. New discoveries, novel techniques and fresh lines of inquiry are outlined and discussed.
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Chemical evidence is presented with previously reported morphological features for banded-tube cell types in the earliest known plant fossils associated with stream-deposited sediments. Phenolic aldehydes (p-hydroxybenzaldehyde, vanillin) and aromatic compounds from pyrolysis (2-methoxy-4-hydroxybenzaldehyde, methylsyringaldehyde) derived from cellular remains are interpreted as evidence for lignin or lignin-like degradation products. The presence of parallel-aligned banded tubes, with annular to spiral thickenings and occasional end walls, in conjunction with lignin-like constituents fulfill most of the morphological and chemical criteria for cell types that could have functioned as water-conducting cells.
Prototaxites southworthii. an Upper Devonian, nonvascular plant of unknown affinity that is commonly ascribed to the brown algae, has filaments with septal pores. These superficially resemble various pores and pit connections of the higher algae and fungi and suggest that very elaborate cell wall structure had evolved by Devonian times.