Yan-Chun Li

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.

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.

Epidermal growth factor receptors (EGFR) contribute to colonic tumorigenesis in experimental models of colon cancer. We previously showed that EGFR was also required for colonic tumor promotion by Western diet. The goal of this study was to identify EGFR-regulated microRNAs that contribute to diet-promoted colonic tumorigenesis. Murine colonic tumors from Egfr(wt) and hypomorphic Egfr(wa2) mice were screened using micro RNA (miRNA) arrays and miR-143 and miR-145 changes confirmed by Northern, real-time PCR, and in situ analysis. Rodent and human sporadic and ulcerative colitis (UC)-associated colon cancers were examined for miR-143 and miR-145. Effects of EGFR on miR-143 and miR-145 expression were assessed in murine and human colonic cells and their putative targets examined in vitro and in vivo. miR-143 and miR-145 were readily detected in normal colonocytes and comparable in Egfr(wt) and Egfr(wa2) mice. These miRNAs were downregulated in azoxymethane and inflammation-associated colonic tumors from Egfr(wt) mice but upregulated in Egfr(wa2) tumors. They were also reduced in human sporadic and UC colon cancers. EGFR signals suppressed miR-143 and miR-145 in human and murine colonic cells. Transfected miR-143 and miR-145 inhibited HCT116 cell growth in vitro and in vivo and downregulated G(1) regulators, K-Ras, MYC, CCND2, cdk6, and E2F3, putative or established targets of these miRNAs. miRNA targets Ras and MYC were increased in colonic tumors from Egfr(wt) but not Egfr(wa2) mice fed a Western diet. EGFR suppresses miR-143 and miR-145 in murine models of colon cancer. Furthermore, Western diet unmasks the tumor suppressor roles of these EGFR-regulated miRNAs.

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.

A new distinct genus of Boletales, Zangia, with phenotypic similarities to the genus Tylopilus, is proposed based on molecular and morphological data. The monophyly of Zangia was highly supported using two nuclear and three mitochondrial genes based on Maximum Parsimony, Maximum Likelihood and Bayesian analyses. Morphologically, Zangia is distinguished from other boletoid lineages by its combination of rugose pileus, pinkish to pink hymenophore, pink to pinkish brown spore deposit, pink scabrous squamules on the stipe, chrome yellow to golden yellow stipe base, chrome yellow to golden yellow mycelia on the base of the stipe, ixohyphoepithelium pileipellis, glabrous spores and bluish colour changes in the stipe in some species. Geographically, Zangia is currently only known from southern, southeastern and southwestern China under forests dominated by Fagaceae mixed with Pinaceae. Six species, including 4 new ones and 2 new combinations, are fully documented with taxonomic descriptions and illustrations. A key to the species in Zangia is provided. It is suggested that some of the species might have started diverging from each other relatively recently with the uplifts of the eastern Himalayas and Hengduan Mountains, and both the mycorrhizal host specificity or preference and geographic separation could contribute to their ongoing divergence.