Phylogenetic systematics of Syncephalis (Zoopagales, Zoopagomycotina), a genus of ubiquitous mycoparasites.

We examined phylogenetic relationships among species of the mycoparasite genus Syncephalis using sequences from three nuclear ribsosomal DNA genes (18S, 5.8S, and 28S nuc rDNA) and a gene encoding the largest subunit of RNA polymerase II (RPB1). Our data set included 88 Syncephalis isolates comprising 23 named species and several unnamed taxa. We also revived a culturing technique using beef liver and cellophane to grow several Syncephalis isolates without their host fungi to obtain pure parasite DNA. Most isolates, however, were grown in co-cultures with their host fungi, so we designed Syncephalis-specific primers to obtain sequence data. Individual and combined data sets were analyzed by maximum likelihood (ML) and Bayesian methods. We recovered 20 well-supported lineages and 38 operational taxonomic units (OTUs). Most major clades contained isolates from distant localities on multiple continents. There were taxonomic and nomenclature issues within several clades, probably due to high phenotypic plasticity or species dimorphism. We also conducted an analysis of Syncephalis nuc rDNA internal transcribed spacer (ITS) sequences for 31 phylogenetically diverse isolates, and we determined that most Syncephalis species have long ITS sequences relative to other fungi. Although commonly employed eukaryotic and fungal primers are compatible with diverse Syncephalis species, the ITS sequences of Syncepahlis are nonetheless rarely recovered in environmental molecular diversity surveys.

Five new species of the obligate mycoparasite Syncephalis (Zoopagales, Zoopagomycotina) from soil.

More than 520 soil samples were surveyed for species of the mycoparasitic zygomycete genus Syncephalis using a culture-based approach. These fungi are relatively common in soil using the optimal conditions for growing both the host and parasite. Five species obtained in dual culture are unknown to science and are described here: (i) S. digitata with sporangiophores short, merosporangia separate at the apices, simple, 3-5 spored; (ii) S. floridana, which forms galls in the host and has sporangiophores up to 170 µm long with unbranched merosporangia that contain 2-4 spores; (iii) S. pseudoplumigaleta, with an abrupt apical bend in the sporophore; (iv) S. pyriformis with fertile vesicles that are long-pyriform; and (v) S. unispora with unispored merosporangia. To facilitate future molecular comparisons between species of Syncephalis and to allow identification of these fungi from environmental sampling datasets, we used Syncephalis-specific PCR primers to generate internal transcribed spacer (ITS) sequences for all five new species.

Genome sequencing provides insight into the reproductive biology, nutritional mode and ploidy of the fern pathogen Mixia osmundae.

Mixia osmundae (Basidiomycota, Pucciniomycotina) represents a monotypic class containing an unusual fern pathogen with incompletely understood biology. We sequenced and analyzed the genome of M. osmundae, focusing on genes that may provide some insight into its mode of pathogenicity and reproductive biology. Mixia osmundae has the smallest plant pathogenic basidiomycete genome sequenced to date, at 13.6 Mb, with very few repeats, high gene density, and relatively few significant gene family gains. The genome shows that the yeast state of M. osmundae is haploid and the lack of segregation of mating genes suggests that the spores produced on Osmunda spp. fronds are probably asexual. However, our finding of a complete complement of mating and meiosis genes suggests the capacity to undergo sexual reproduction. Analyses of carbohydrate active enzymes suggest that this fungus is a biotroph with the ability to break down several plant cell wall components. Analyses of publicly available sequence data show that other Mixia members may exist on other plant hosts and with a broader distribution than previously known.