A fissitunicate ascus mechanism in the Calosphaeriaceae, and novel species of <I>Jattaea</I> and <I>Calosphaeria</I> on <I>Prunus</I> wood

Abstract

During a survey of Prunus wood from South Africa, isolations were made of three presumably Calosphaerialean fungi that formed hyphomycetous, phialidic anamorphs in culture. In order to reveal the phylogenetic relationship of these fungi, they were characterised on a morphological and molecular (LSU and ITS rDNA) basis. Two isolates that formed a teleomorph in culture are newly described as Calosphaeria africana sp. nov. Although asci of Calosphaeria are characterised by having non-amyloid apical rings, two functional wall layers were observed in asci of C. africana, which has hitherto not been observed in any member of the Calosphaeriaceae. However, Calosphaeriaceae (Calosphaeriales, Sordariomycetes) are not closely related to other bitunicate fungi like Dothideomycetes, Chaetothyriales and bitunicate lichens. Possession of two separating wall layers is considered to be a result of both inherited abilities and convergent evolution under a strong selection pressure of the environmental conditions that favour an extension of the ascus. The other two species represented a separate lineage within Calosphaeriaceae, and formed phialophora-like anamorphs. By obtaining the teleomorph in culture, one of them could be identified as a species of Jattaea, described here as Jattaea prunicola sp. nov., while the second, which only produced the anamorph, is named as Jattaea mookgoponga sp. nov. These findings suggest that some species of Jattaea are true members of the Calosphaeriaceae, though the phylogenetic relation of the type, J. algeriensis, remains unknown. Furthermore, it also represents the first report of Jattaea on Prunus wood, and from South Africa.

New insights into the systematics and phylogeny of the genus Jattaea and similar fungi of the Calosphaeriales

“…Notes: The paraphyses were seen only as fragments in the holotype collection. Damm et al (2008) isolated J. algeriensis (as prunicola) from wood of Prunus salicina displaying necrotic symptoms; the perithecia and the phialophora-like anamorph developed in axenic culture. The anamorph formed cylindrical, elongate-ampulliform to ampulliform phialides on aerial mycelium, while hyphae bearing adelophialides were predominantly submerged in the agar medium; conidia are suballantoid to oblong, hyaline.…”

“…The new sequences were aligned with data retrieved from GenBank, mostly from studies published by Spatafora et al (2007) and Zhang et al (2007). Other DNA data of members of the Calosphaeriales were published by Damm et al (2008), Mostert et al (2006), Réblová (2006), Réblová and Mostert (2007), Réblová and Štěpánek (2009) and Vijaykrishna et al (2004). Accession numbers of analysed sequences are given in the phylograms (Figs.…”

“…Perithecia often develop solitarily or in circinate groups on wood beneath the loosened periderm or in soft, decaying wood. Recently, they were also isolated from wood of branches and trunks of fruit trees showing canker symptoms (Damm et al 2008;Trouillas et al 2010), a substratum domain generally believed to be restricted to the morphologically similar Togniniaceae (e.g. Mostert et al 2006).…”

Pyrigemmula, a novel hyphomycete genus on grapevine and tree bark

“…Stems and branches of woody hosts such as grapevines and fruit trees have in recent years been shown to share the same range of fungi, which are able to migrate between these different hosts (Mostert et al 2005(Mostert et al , 2006Damm et al 2007Damm et al , 2008aDamm et al , b, 2010Essakhi et al 2008). This movement of fungal organisms is usually enhanced by the fact that vineyards are frequently planted adjacent to fruit tree orchards.…”

“…Upon closer examination, many of these fungi are associated with symptoms of brown wood discoloration, although several appear to simply be endophytic or saprobic (Van Niekerk et al 2004;Mostert et al 2006). These include several hyphomycetes such as Phaeomoniella (Petri disease in grapevines, and brown wood streaking in fruit trees; Mostert et al 2006;Damm et al 2008a), Phaeoacremonium/ Togninia (brown wood streaking; Mostert et al 2006;Essakhi et al 2008), Coniochaeta/Lecythophora (endophytes on various substrates, but also pathogens of humans, and associated with food spoilage; Damm et al 2010), Collophora (brown wood streaking; Damm et al 2010), Calosphaeria and Jattaea species (endophytic in wood and bark; Damm et al 2008a). Several coelomycetous species have also been found to share these hosts, namely species of Paraconiothyrium (endophytic, plant pathogenic; Damm et al 2008b), and members of the Botryosphaeriaceae (endophytic, plant pathogenic; Slippers et al 2007;Phillips et al 2008), to name but a few.…”