Persoonia最新文献

The genus Neocosmospora (Fusarium solani species complex) contains saprobes, plant endophytes and pathogens of major economic significance as well as opportunistic animal pathogens. Advances in biological and phylogenetic species recognition revealed a rich species diversity which has largely remained understudied. Most of the currently recognised species lack formal descriptions and Latin names, while the taxonomic utility of old names is hampered by the lack of nomenclatural type specimens. Therefore, to stabilise the taxonomy and nomenclature of these important taxa, we examined type specimens and representative cultures of several old names by means of morphology and phylogenetic analyses based on rDNA (ITS and LSU), rpb2 and tef1 sequences. Sixty-eight species are accepted in Neocosmospora, 29 of them described herein as new; while 13 new combinations are made. Eleven additional phylogenetic species are recognized, but remain as yet undescribed. Lectotypes are proposed for eight species, seven species are epitypified and two species are neotypified. Notes on an additional 17 doubtful or excluded taxa are provided.

The Fusarium incarnatum-equiseti species complex (FIESC) is a phylogenetically species-rich complex that includes over 30 cryptic phylogenetic species, making identification based on phenotypic characters problematic. Several established Fusarium species known to reside in the FIESC lack type material, further complicating the use of Latin binomials for this complex. To overcome this problem, an informal classification system based on a haplotype nomenclature was introduced to improve communication between researchers in various fields. However, some conflicts in the application of this nomenclature system have arisen. To date, 16 phylo-species in the FIESC have been provided with Latin binomials with approximately 18 FIESC phylo-species still lacking Latin binomials, the majority of which reside in the Incarnatum clade. The aim of this study is to introduce Latin binomials for the unnamed FIESC phylo-species based on phylogenetic inference supported by phenotypic characters. The three-gene (calmodulin, RNA polymerase II second largest subunit and translations elongation factor 1-alpha) phylogenetic inference resolved 47 lineages, of which 44 belonged to the FIESC. The F. camptoceras species complex (FCAMSC) is introduced here for three lineages that are distinct from the FIESC. Epitypes are designated for F. compactum, F. incarnatum and F. scirpi, and a neotype for F. camptoceras. Latin binomials are provided for 20 of these newly resolved phylo-species in the FIESC.

Fusarium species are well known for their abundance, diversity and cosmopolitan life style. Many members of the genus Fusarium are associated with plant hosts, either as plant pathogens, secondary invaders, saprotrophs, and/or endophytes. We previously studied the diversity of Fusarium species in the Fusarium oxysporum species complex (FOSC) associated with Fusarium wilt of banana in Indonesia. In that study, several Fusarium species not belonging to the FOSC were found to be associated with Fusarium wilt of banana. These Fusarium isolates belonged to three Fusarium species complexes, which included the Fusarium fujikuroi species complex (FFSC), Fusarium incarnatum-equiseti species complex (FIESC) and the Fusarium sambucinum species complex (FSSC). Using a multi-gene phylogeny that included partial fragments of the beta-tubulin (tub), calmodulin (cmdA), translation elongation factor 1-alpha (tef1), the internal transcribed spacer region of the rDNA (ITS), the large subunit of the rDNA (LSU), plus the RNA polymerase II large subunit (rpb1) and second largest subunit (rpb2) genes, we were able to identify and characterise several of these as new Fusarium species in the respective species complexes identified in this study.

Fusarium oxysporum is the most economically important and commonly encountered species of Fusarium. This soil-borne fungus is known to harbour both pathogenic (plant, animal and human) and non-pathogenic strains. However, in its current concept F. oxysporum is a species complex consisting of numerous cryptic species. Identification and naming these cryptic species is complicated by multiple subspecific classification systems and the lack of living ex-type material to serve as basic reference point for phylogenetic inference. Therefore, to advance and stabilise the taxonomic position of F. oxysporum as a species and allow naming of the multiple cryptic species recognised in this species complex, an epitype is designated for F. oxysporum. Using multi-locus phylogenetic inference and subtle morphological differences with the newly established epitype of F. oxysporum as reference point, 15 cryptic taxa are resolved in this study and described as species.

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.

Although Aspergillus fumigatus is the major agent of invasive aspergillosis, an increasing number of infections are caused by its cryptic species, especially A. lentulus and the A. viridinutans species complex (AVSC). Their identification is clinically relevant because of antifungal drug resistance and refractory infections. Species boundaries in the AVSC are unresolved since most species have uniform morphology and produce interspecific hybrids in vitro. Clinical and environmental strains from six continents (n = 110) were characterized by DNA sequencing of four to six loci. Biological compatibilities were tested within and between major phylogenetic clades, and ascospore morphology was characterised. Species delimitation methods based on the multispecies coalescent model (MSC) supported recognition of ten species including one new species. Four species are confirmed opportunistic pathogens; A. udagawae followed by A. felis and A. pseudoviridinutans are known from opportunistic human infections, while A. felis followed by A. udagawae and A. wyomingensis are agents of feline sino-orbital aspergillosis. Recently described human-pathogenic species A. parafelis and A. pseudofelis are synonymized with A. felis and an epitype is designated for A. udagawae. Intraspecific mating assay showed that only a few of the heterothallic species can readily generate sexual morphs in vitro. Interspecific mating assays revealed that five different species combinations were biologically compatible. Hybrid ascospores had atypical surface ornamentation and significantly different dimensions compared to parental species. This suggests that species limits in the AVSC are maintained by both pre- and post-zygotic barriers and these species display a great potential for rapid adaptation and modulation of virulence. This study highlights that a sufficient number of strains representing genetic diversity within a species is essential for meaningful species boundaries delimitation in cryptic species complexes. MSC-based delimitation methods are robust and suitable tools for evaluation of boundaries between these species.