Fungal systematics and evolution最新文献

Holocarpic oomycetes convert their entire cytoplasm into zoospores and thus do not form dedicated sporangia or hyphal compartments for asexual reproduction. The majority of holocarpic oomycetes are obligate parasites and parasitoids of a diverse suite of organisms, among them green and red algae, brown seaweeds, diatoms, fungi, oomycetes and invertebrates. Most of them are found among the early diverging oomycetes or the Peronosporomycetes, and some in the early-diverging Saprolegniomycetes (Leptomitales). The obligate parasitism renders it difficult to study some of these organisms. Only a few members of the genus Haliphthoros s. l. have been cultured without their hosts, and of the parasitoid Leptomitales, some transient cultures have been established, which are difficult to maintain. Here, the cultivation of a new holocarpic oomycete genus of the Leptomitales, Bolbea, is presented. Bolbea is parasitic to ostracods, is readily cultivable on malt extract agar, and upon contact with water converts its cytoplasm into zoospores. Its morphology and phylogenetic relationships are reported. Due to the ease of cultivation and the ready triggering of zoospore development, similar to some lagenidiaceous oomycetes, the species could be a promising model to study sporulation processes in detail.

Species of Raffaelea (Ophiostomatales: Ascomycota) are obligate symbionts of ambrosia beetles, some of which pose a substantial threat to forest trees. Leucaena leucocephala is a small mimosoid tree species that is considered as an invasive weed in most of its introduced range globally. During a field expedition on the French island of Réunion, dying L. leucocephala trees were observed. Samples were taken from these trees and isolations made from symptomatic wood tissues that included beetle tunnels, but in the absence of the beetles themselves. Multiple isolates of a fungus resembling a Raffaelea species were obtained from the discoloured wood associated with the beetle tunnels. To determine their identity, microscopic examination was performed and DNA sequences for three gene regions (ITS, LSU, TUB) were obtained. Phylogenetic analyses based on these gene regions revealed that the isolates represent a new species of Raffaelea, described here as R. borbonica sp. nov. A pathogenicity test was conducted with the fungus, which was shown to cause lesions on the inoculated seedlings, but with a low level of aggressiveness.

Acacia mangium plantations account for more than 50 % of the exotic plantations in Vietnam. A new black butt symptom was discovered in 2012, followed by the wilting sign in Acacia seedlings in Tuyen Quang Province. Isolations recovered two Phytophthora species, the well-known Acacia pathogen P. cinnamomi, and an unknown species. The new species is described here as Phytophthora acaciivora sp. nov. Phylogenetically this species resides in clade 2d and is most closely related to P. frigida. Phytophthora acaciivora is a heterothallic species, oospores are aplerotic and antheridia are amphigynous. It produces predominantly elongated ovoid, semi papillate, persistent sporangia, no hyphal swellings and no chlamydospores. Optimum temperature for the growth is 25-30 °C and the maximum temperature is over 37.5 °C. Studies are underway to determine the impact of this new species on Acacia plantations in Vietnam.

Phylogenetic analyses of 115 newly collected Helvella specimens from Spain using three genetic markers [heat shock protein 90 (hsp), RNA polymerase II second largest subunit (rpb2) and the nuclear large subunit ribosomal DNA (LSU)] confirm the assignment of the Spanish collections to one Dissingia and 30 Helvella species. The analyses were supplemented with an additional sample of 65 Spanish and extralimital Helvella specimens from the fungaria of Oslo (O), Trondheim (TRH), Copenhagen (C), Uppsala (UPS), Stockholm (S) and Venice (MCVE). Nine species are described as new, i.e. Helvella fuscolacunosa, H. hispanica, H. iberica, H. inexpectata, H. neopallescens, H. phlebophoroides, H. poculiformis, H. retinervis, and H. terricola. We present photographs of a selection of fresh specimens and provide descriptions of all species of this diverse South European Mediterranean element of the genera in Europe.

The PhyloCode is used to classify taxa based on their relation to a most recent common ancestor as recovered from a phylogenetic analysis. We examined the first specimen of Cintractiella (Ustilaginomycotina) collected from Australia and determined its systematic relationship to other Fungi. Three ribosomal DNA loci were analysed both with and without constraint to a phylogenomic hypothesis of the Ustilaginomycotina. Cintractiella did not share a most recent common ancestor with other orders of smut fungi. We used the PhyloCode to define the Cintractiellales, a monogeneric order with four species of Cintractiella, including C. scirpodendri sp. nov. on Scirpodendron ghaeri. The Cintractiellales may have shared a most recent common ancestor with the Malasseziomycetes, but are otherwise unresolved at the rank of class.