Studies of Paleozoic Fungi. Iii. Fungal Parasitism in a Pennsylvanian Gymnosperm

Abstract

Evidence of fungal parasitism is found in the Pennsylvanian gymnospermous cone, Lasiostrobus polysacci Taylor. Indication of fungal activity is found in the outer cortical region of the axis of the cone and in the fleshy microsporophylls. Specimens exhibit severe tissue disruption, thick‐walled, branched, septate hyphae, and possible reproductive structures. Parenchymatous cortical cells may also contain rounded bodies which are continuous with the cell wall. Similar structures are formed in many extant taxa in response to fungal invasion, and are termed wall appositions or callosities. Although their role in extant plants is disputed, they are clearly the product of a living host cell. Such spherical bodies, however, are not restricted to the cell periphery but in some cases occlude the cell lumen. In appearance they resemble resinous remains similar to those found in other coal ball plants. The blockage of entire cells or groups of cells may have served to retard hyphal growth or isolate infected cells. The occurrence of such structures in a Carboniferous plant provides the best evidence to date of parasitism during the Paleozoic.

Oldest fossil basidiomycete clamp connections

“…This type of host reaction has been observed in cells of numerous extant seed plants (Young 1926;Rioux and Biggs 1994) but is also known to occur in ferns (Archer and Cole 1986). It has also been recorded for several fossils, including the xylem and periderm of a lycophyte from the upper Visean of France (Krings et al 2009) and a staminate gymnosperm strobilus from the Upper Pennsylvanian (*300 Ma) of North America (Stubblefield et al 1984), but we are not aware of any previous record in fossil ferns.…”

“…1m,n) formed in response to invading clamp-bearing hyphae, then this host response would favor evidence of a parasitic infection. Callosities (also called appositions, lignotubers, or papillae, among other terms; see Stubblefield et al 1984) assume a variety of shapes, from wart-like to elongate conical, and represent inwardly directed projections consisting of newly synthesized wall material that are formed by living plant cells (but also by certain fungal spores) in response to invading fungi. Callosities encase the invading fungal hypha or filament, and it is widely interpreted that they are effective in preventing or retarding penetration by the parasite (Aist 1977).…”

First record of fossil basidiomycete clamp connections in cordaitalean stems from the Asselian–Sakmarian (lower Permian) of Shanxi Province, North China

“…Stubblefield et al, 1985;Stubblefield and Taylor, 1986;Taylor, 1993;Krings et al, 2007;Harper et al, 2012). Nevertheless, in most cases the relationship between a fossil fungus and its host is difficult to determine because the only available information is the morphology of a single phase of the life cycle of the fungus (Stubblefield et al, 1984;Taylor and Krings, 2005). Based on materials in this study, the biological nature of the relationship between Shanxioxylon sp.…”

Fossils of parasitic fungi

“…Fossils similar to C. acuminata have been described in roots from the Triassic of the Svalbard archipelago by McLoughlin and Strullu-Derrien (2016). Other evidence of fungal parasitism in Pennsylvanian plants occurs in a Lasiostrobus polysaccii cone from Illinois, USA (˜310 Ma) (Stubblefield et al ., 1984). On the inner surface of cortical cells containing fungal hyphae are peculiar swellings that appear to represent wall appositions produced by the host in response to the infection.…”