Identification of New Fungal Pathogens of Coast Live Oak in California

Taxonomy and pathogenicity of fungi associated with oak decline in northern and central Zagros forests of Iran with emphasis on coelomycetous species

Oak decline is a complex disorder that seriously threatens the survival of Zagros forests. In an extensive study on taxonomy and pathology of fungi associated with oak decline in the central and northern part of Zagros forests, 462 fungal isolates were obtained from oak trees showing canker, gummosis, dieback, defoliation, and partial or total death symptoms. Based on inter-simple sequence repeat (ISSR) fingerprinting patterns, morphological characteristics, and sequences of ribosomal DNA (28S rDNA and ITS) and protein coding loci (acl1, act1, caM, tef-1α, rpb1, rpb2, and tub2), 24 fungal species corresponding to 19 genera were characterized. Forty percent of the isolates were placed in eight coelomycetous species from seven genera, namely, Alloeutypa, Botryosphaeria, Cytospora, Didymella, Gnomoniopsis, Kalmusia, and Neoscytalidium. Of these, four species are new to science, which are introduced here as taxonomic novelties: Alloeutypa iranensis sp. nov., Cytospora hedjaroudei sp. nov., Cytospora zagrosensis sp. nov., and Gnomoniopsis quercicola sp. nov. According to pathogenicity trials on leaves and stems of 2-year-old Persian oak (Quercus brantii) seedlings, Alternaria spp. (A. alternata, A. atra, and A. contlous), Chaetomium globosum, and Parachaetomium perlucidum were recognized as nonpathogenic. All coelomycetous species were determined as pathogenic in both pathogenicity trials on leaves and seedling stems, of which Gnomoniopsis quercicola sp. nov., Botryosphaeria dothidea, and Neoscytalidium dimidiatum were recognized as the most virulent species followed by Biscogniauxia rosacearum.

Assessment of functional and structural changes of soil fungal and oomycete communities in holm oak declined dehesas through metabarcoding analysis

Forest decline is nowadays a major challenge for ecosystem sustainability. Dehesas, which consists of savannah-like mediterranean ecosystems, are threatened by the holm oak decline in the south-west of Iberian Peninsula. Phytophthora cinnamomi is considered the main agent of holm oak root rot, but little is known about the relationship between diversity of soilborne microbial community and the decline syndrome of holm oak. It would be hypothesized that the changes in the structure and functionality of the soil microbiome might influence tree health status through changes in richness and diversity of beneficial organisms such as mycorrhizal species, or fungal plant pathogens such as Fusarium spp. or Alternaria spp. Total DNA of soil samples from declined oak dehesas was extracted and analyzed through metabarcoding techniques, to evaluate the specific composition and diversity of the fungal and oomycete communities and their relationship with the disease symptoms. The fungal community included a wide range of pathogens and abundance of ectomycorrhizal key taxa related with low defoliation degree. Phytophthora cinnamomi and Pythium spiculum did not appear among the most abundant oomycetes, nor were they related directly to defoliation levels. Moreover, a particular taxon belonging to the genus Trichoderma was strongly correlated with the scarcity of pathogenic Phytophthora spp. The diversity and composition of fungal and oomycete communities were related to the severity of the decline symptoms. The metabarcoding study of microbiome represents a powerful tool to develop biocontrol strategies for the management of the holm oak root rot.

Phaeoacremonium species diversity on woody hosts in the Western Cape Province of South Africa

Nineteen Phaeoacremonium species are currently known in South Africa. These have been reported from grapevines, fruit trees, fynbos twig litter and arthropods. In other countries some of these Phaeoacremonium species are also known from hosts such as European olive, quince and willow that commonly occur in the Western Cape Province of South Africa, where most South African records of Phaeoacremonium have been made. The aim of this study was to investigate the species diversity and host-range of Phaeoacremonium in the Western Cape Province of South Africa by characterising 156 isolates collected from 29 woody hosts. Phylogenetic analyses of combined actin and beta-tubulin datasets allowed for the identification of 31 species among the 156 isolates, including 13 new species and 3 known species that had not been recorded in South Africa previously. The new Phaeoacremonium species include P. album, P. aureum, P. bibendum, P. gamsii, P. geminum, P. junior, P. longicollarum, P. meliae, P. oleae, P. paululum, P. proliferatum, P. rosicola and P. spadicum. All previous records of P. alvesii in South Africa were re-identified as P. italicum, but both species were recovered during this survey. A total of 35 described Phaeoacremonium species are now known from South Africa, more than double the number reported from any other country. This high diversity reflects the high diversity of indigenous flora of the Cape Floral Region, a biodiversity hotspot mainly situated in the Western Cape Province. Paraphyly and incongruence between individual phylogenies of the actin and beta-tubulin regions complicated species delimitation in some cases indicating that additional phylogenetic markers should be investigated for use in Phaeoacremonium phylogenies to prevent misidentifications and the introduction of vague species boundaries.

Redefining common endophytes and plant pathogens in Neofabraea, Pezicula, and related genera

Species in Neofabraea, Pezicula, and related genera have been reported as saprobes, plant pathogens or endophytes from a wide range of hosts. The asexual morphs of Neofabraea and Pezicula had been placed in Cryptosporiopsis, now a synonym of Pezicula, while Neofabraea was also linked to Phlyctema. Based on morphology and molecular data of the partial large subunit nrDNA (LSU), the internal transcribed spacer region with intervening 5.8S nrDNA (ITS), partial β-tubulin region (tub2), and the partial RNA polymerase II second largest subunit region (rpb2), the taxonomy and phylogenetic relationships of these fungi were investigated. Five new species were described in Pezicula based on morphology, while a further eight unnamed phylogenetic lineages revealed further diversity in the genus. Based on these results, the generic concept of Neofabraea was also emended. Phlyctema, which was previously associated with Neofabraea, formed a distinct clade, separate from Neofabraea s. str. Two new neofabraea-like genera, Parafabraea and Pseudofabraea were proposed, along with one new combination in Neofabraea s. str. To stabilise the application of these names, an epitype was designated for Pe. carpinea, the type species of Pezicula, and for N. malicorticis, the type species of Neofabraea.

Phaeoacremonium: from esca disease to phaeohyphomycosis

Phaeoacremonium spp. are commonly isolated from stems and branches of diseased woody hosts, and humans with phaeohyphomycosis. The genus Phaeoacremonium (Togniniaceae, Togniniales) has recently been monographed, and presently contains 46 species, while its sexual morph, Togninia, contains 26 epithets, of which 13 are insufficiently known. In this review we summarise information pertaining to the global distribution, pathology, ecology, and detection of these species, and present a case for retaining the genus Phaeoacremonium over that of Togninia. Furthermore, to obtain a single nomenclature, the following new combinations are also proposed: Phaeoacremonium africanum, P. aquaticum, P. fraxinopennsylvanicum, P. griseo-olivaceum, P. inconspicuum, P. leptorrhynchum, P. minimum, and P. vibratile.

Recommendations on generic names competing for use in Leotiomycetes (Ascomycota)

In advancing to one scientific name for fungi, this paper treats genera competing for use in the phylogenetically defined class Leotiomycetes except for genera of Erysiphales. Two groups traditionally included in the so-called "inoperculate discomycetes" have been excluded from this class and are also not included here, specifically Geoglossomycetes and Orbiliomycetes. A recommendation is made about the generic name to use in cases in which two or more generic names are synonyms or taxonomically congruent along with the rationale for the recommendation. In some cases the recommended generic name does not have priority or is based on an asexual type species, thus needs to be protected and ultimately approved according to Art. 57.2 of the International Code of Nomenclature for algae, fungi and plants (ICN). A table is presented listing all competing generic names and their type species noting the recommended generic name. New combinations are introduced for the oldest epithet in the recommended genus including Ascocalyx berenice, Ascoconidium purpurascens, Ascocoryne albida, A. trichophora, Blumeriella filipendulae, B. ceanothi, Botrytis arachidis, B. fritillariae-pallidoflori, Calloria urticae, Calycellina aspera, Dematioscypha delicata, Dermea abietinum, D. boycei, D. stellata, Diplocarpon alpestre, D. fragariae, Godroniopsis peckii, Grovesinia moricola, Heterosphaera sublineolata, Hyphodiscus brachyconium, H. brevicollaris, H. luxurians, Leptotrochila campanulae, Monilinia polystroma, Neofabraea actinidae, N. citricarpa, N. vagabunda, Oculimacula aestiva, O. anguioides, Pezicula brunnea, P. californiae, P. cornina, P. diversispora, P. ericae, P. melanogena, P. querciphila, P. radicicola, P. rhizophila, Phialocephala piceae, Pilidium lythri, Rhabdocline laricis, Streptotinia streptothrix, Symphyosirinia parasitica, S. rosea, Unguiculariopsis caespitosa, and Vibrissea laxa.

New Phaeoacremonium species isolated from sandalwood trees in Western Australia

Thirty-eight Phaeoacremonium isolates collected from pruning wounds of tropical sandalwood in Western Australia were studied with morphological and cultural characteristics as well as phylogenetic analyses of combined DNA sequences of the actin and β-tubulin genes. Three known Phaeoacremonium species were found, namely P. alvesii, P. parasiticum, and P. venezuelense. Phaeoacremonium venezuelense represents a new record for Australia. Two new species are described: P. luteum sp. nov. can be identified by the ability to produce yellow pigment on MEA, PDA, and OA, the predominance of subcylindrical to subulate type II phialides, and the mycelium showing prominent exudate droplets observed as warts; and P. santali sp. nov. which can be separated from other species producing pink colonies on MEA by the predominance of type I and II phialides, the distinct brownish olive colonies in OA, and slow growth.