Yan-Chun Li

DNA Sequence Analyses Reveal Abundant Diversity, Endemism and Evidence for Asian Origin of the Porcini Mushrooms

The wild gourmet mushroom Boletus edulis and its close allies are of significant ecological and economic importance. They are found throughout the Northern Hemisphere, but despite their ubiquity there are still many unresolved issues with regard to the taxonomy, systematics and biogeography of this group of mushrooms. Most phylogenetic studies of Boletus so far have characterized samples from North America and Europe and little information is available on samples from other areas, including the ecologically and geographically diverse regions of China. Here we analyzed DNA sequence variation in three gene markers from samples of these mushrooms from across China and compared our findings with those from other representative regions. Our results revealed fifteen novel phylogenetic species (about one-third of the known species) and a newly identified lineage represented by Boletus sp. HKAS71346 from tropical Asia. The phylogenetic analyses support eastern Asia as the center of diversity for the porcini sensu stricto clade. Within this clade, B. edulis is the only known holarctic species. The majority of the other phylogenetic species are geographically restricted in their distributions. Furthermore, molecular dating and geological evidence suggest that this group of mushrooms originated during the Eocene in eastern Asia, followed by dispersal to and subsequent speciation in other parts of Asia, Europe, and the Americas from the middle Miocene through the early Pliocene. In contrast to the ancient dispersal of porcini in the strict sense in the Northern Hemisphere, the occurrence of B. reticulatus and B. edulis sensu lato in the Southern Hemisphere was probably due to recent human-mediated introductions.

Molecular phylogenetic analyses redefine seven major clades and reveal 22 new generic clades in the fungal family Boletaceae

Mushrooms in the basidiomycete family Boletaceae are ecologically and economically very important. However, due to the morphological complexity and the limited phylogenetic information on the various species and genera of this fungal family, our understanding of its systematics and evolution remains rudimentary. In this study, DNA sequences of four genes (nrLSU, tef1-α, rpb1, and rpb2) were newly obtained from ca. 200 representative specimens of Boletaceae. Our phylogenetic analyses revealed seven major clades at the subfamily level, namely Austroboletoideae, Boletoideae, Chalciporoideae, Leccinoideae, Xerocomoideae, Zangioideae, and the Pulveroboletus Group. In addition, 59 genus-level clades were identified, of which 22 were uncovered for the first time. These 22 clades were mainly placed in Boletoideae and the Pulveroboletus Group. The results further indicated that the characters frequently used in the morphology-based taxonomy of Boletaceae, such as basidiospore ornamentation, the form of the basidioma, and the stuffed pores each had multiple origins within the family, suggesting that the use of such features for high-level classification of Boletaceae should be de-emphasized and combined with other characters.

Recombination and genetic differentiation among natural populations of the ectomycorrhizal mushroom Tricholoma matsutake from southwestern China

Effective conservation and utilization strategies for natural biological resources require a clear understanding of the natural populations of the target organisms. Tricholoma matsutake is an ectomycorrhizal mushroom that forms symbiotic associations with plants and plays an important ecological role in natural forest ecosystems in many parts of the world. It is also an economically very important gourmet mushroom. Because no artificial cultivation is available, natural populations of this species are under increasing threats, primarily from habitat disturbance and destruction. Despite its economical and ecological importance, little is known about its genetics and population biology. Here, using 14 polymerase chain reaction–restriction fragment length polymorphism markers, we analysed 154 strains from 17 geographical locations in southwestern China, a region where over 25% of the global T. matsutake harvest comes from. Our results revealed abundant genetic variation within individual populations. The analyses of gene and genotype frequencies within populations indicated that most loci did not deviate from Hardy–Weinberg equilibrium in most populations and that alleles among loci were in linkage equilibrium in the majority of the local populations. These results are consistent with the hypothesis that sexual reproduction and recombination play an important role in natural populations of this species. Our analyses indicated low but significant genetic differentiation among the geographical populations, with a significant positive correlation between genetic distance and geographical distance. We discuss the implications of our results to the ecology and resource management of this species.

The genus Phylloporus ( Boletaceae, Boletales ) from China: morphological and multilocus DNA sequence analyses

Species of the genus Phylloporus in China were investigated based on morphology and molecular phylogenetic analysis of a three-locus (nrLSU, ITS and tef-1a) DNA sequence dataset. Twenty-one phylogenetic species were recognized among the studied collections. Seven of them are described as new: P. brunneiceps, P. imbricatus, P. maculatus, P. pachycystidiatus, P. rubeolus, P. rubrosquamosus, and P. yunnanensis. In addition, four of them correspond with the previous morphology-based taxa: P. bellus, P. luxiensis, P. parvisporus, and P. rufescens. The remaining ten phylogenetic species were not described due to the paucity of the materials. A key to the Chinese morphologically recognizable taxa was provided. A preliminary biogeographical analysis showed that (1) Pylloporus species in East Asia and Southeast Asia are mostly closely related, (2) species pairs or closely related species of Phylloporus between East Asia and North/Central America are relatively common, and (3) the biogeographic relationship of Phylloporus between East Asia and Europe was supported by only a single species pair. Unexpectedly, no taxa common either to both Europe and East Asia, or to both East Asia and North/Central America, were uncovered. Clades look to have taxa from both sides of the Pacific and Europe/Asia though.

Molecular phylogeny and taxonomy of the genus Veloporphyrellus

Veloporphyrellus is a genus known from North and Central America, southeastern Asia, and Africa. Because species of this genus are phenotypically similar to some taxa in several genera, such as Boletellus, Leccinum, Strobilomyces, Suillus and Tylopilus s.l. belonging to Boletales, its phylogenetic disposition has never been addressed. We analyzed four DNA regions, the nuclear ribosomal LSU and tef-1α, and the mitochondrial mtSSU and atp6 genes, to investigate the phylogenetic disposition of Veloporphyrellus. Although the monophyly of the genus and its systematic placement within the Boletaceae was well supported, its relationship to other genera was not resolved. Morphologically Veloporphyrellus is distinguished from other boletoid genera by the combination of the pinkish or grayish pink hymenophore, the membranous veil hanging on the pilea margin, the trichoderm-like pileus covering and the smooth basidiospores. Five species, including two new species and two new combinations, are described and illustrated. A key to the species of Veloporphyrellus also is provided.

Genetic Diversity of Dahongjun, the Commercially Important "Big Red Mushroom'' from Southern China

Background In southern China, a wild ectomycorrhizal mushroom commonly called “Dahongjun” or “Big Red Mushroom” by the local residents, has been harvested, consumed, and/or exported as an exotic food for many years. Although ecologically and economically important, very little is known about this mushroom, including its diversity and population structure. Methodology and Principal Findings In this study, we analyzed 122 samples from five local populations representing the known distribution ranges of this mushroom in southern China. We investigated the genetic diversity and geographic structure of this mushroom using sequences from four DNA fragments. Our analyses identified that this mushroom contained at least three divergent lineages: one corresponds to a recently described species Russula griseocarnosa from southern China and the remaining two likely represent two novel species. While these lineages were prominently structured geographically based on ITS sequences, evidence for ancient and/or recent gene flow was also identified within individual lineages. In addition, a local population from Ailaoshan in central Yunnan Province where 85 of our 122 specimens came from showed clear evidence of recombination. Conclusion and Significance The ectomycorrhizal mushroom “Dahongjun” from southern China is a species complex with at least three divergent lineages. These lineages are largely geographically structured and there is evidence for recombination in nature. Our results indicate mature Dahongjun mushrooms with abundant basidiospores are important for the reproduction of this mushroom in nature and that individual populations of this species should be managed separately.

One hundred noteworthy boletes from China

Fungi of the family Boletaceae are of great importance in both ecology and economy. Our previous molecular phylogenetic studies have shown this family to have an extremely high species diversity in China. To further document the Chinese boletes, morphological studies and phylogenetic analyses were conducted including species of Boletaceae from China and other parts of the world. The results indicate that seven subfamily-level major clades and 62 generic clades can be retrieved, 52 of which are found in China. Furthermore, 100 species (comprising 32 genera) common in China are illustrated and described here in detail. Among them, four genera and 46 species are new to science, and 26 new combinations are proposed. To interpret the species concepts consistently, epitypes for five species are designated based on collections made from or near the type localities. Notes on eight extralimital species are also provided. Among the species reported here, most of the species are known only from East Asia. Only Leccinum scabrum (Bull.) Gray, Porphyrellus porphyrosporus (Fr. & Hök) E.-J. Gilbert and Tylopilus felleus (Bull.) P. Karst. are widely distributed in the Holarctic, and Buchwaldoboletus lignicola (Kallenb.) Pilát; Strobilomyces strobilaceus (Scop.) Berk. are in Eurasia; while Aureoboletus mirabilis (Murrill) Halling, Harrya chromapes (Frost) Halling et al., and Sutorius eximius (Peck) Halling et al. are found throughout East Asia-North America based on morphological and molecular phylogenetic evidences.

Four new genera of the fungal family Boletaceae

Based on our previous molecular phylogenetic analyses, four new genera are described, namely Baorangia, Lanmaoa, Parvixerocomus, and Rugiboletus, and one known genus, Neoboletus, is re-delimitated. Four new species and nine new combinations are proposed. Morphological characters of each genus and related eleven species are described and illustrated. Most of species in the genera described from southwestern China are wild edible mushrooms and can be found in free markets.

Paraxerula ellipsospora, a new Asian species of Physalacriaceae

A new species, Paraxerula ellipsospora, is described from southwestern China using both morphological and molecular phylogenetic evidence. This species differs phenotypically from the three known species in the genus by its greyish colored pileus, ellipsoid to elongate basidiospores, and a distribution in pine forests in Yunnan. Geographical divergences of Paraxerula in the Holarctic were observed. All species show continental endemisms, yet related species occurring in East Asia and in Europe, or in East Asia and in North America were found.

The taxonomic foundation, species circumscription and continental endemisms of Singerocybe: evidence from morphological and molecular data

The genus Singerocybe (Tricholomataceae, Agaricales, Basidiomycota) has been the subject of controversy since its proposal in 1988. Its taxonomic foundation, species circumscription and geographical distribution have not yet been examined with molecular sequence data. In this study phylogenetic analyses on this group of fungi were conducted based on collections from Europe, eastern Asia, southern Asia, North America and Australia, with four nuclear markers, ITS, nrLSU, tef1-α and rpb2. Molecular phylogenetic analyses, together with morphological observations, strongly support Singerocybe as a monophyletic group and identify the vesicles in the pileal and stipe cuticle as a synapomorphy of this genus. Seven species are recognized in the genus, including one new species and four new combinations. Clitocybe trogioides and Clitocybe trogioides var. odorifera are synonyms of Singerocybe humilis and Singerocybe alboinfundibuliformis respectively. Most of these species are geographically restricted in their distributions. Furthermore our study expands the distribution range of Singerocybe from the North Temperate Zone to Australia (Tasmania) and tropical southern Asia.