Xi-Hui Du

Publications (2)5.77 Total impact

• Article: How well do ITS rDNA sequences differentiate species of true morels (Morchella)?

  Xi-Hui Du, Qi Zhao, Zhu L Yang, Karen Hansen, Hatira Taskin, Saadet Büyükalaca, Damon Dewsbury, Jean-Marc Moncalvo, Greg W Douhan, Vincent A R G Robert, Pedro W Crous, Stephen A Rehner, Alejandro P Rooney, Stacy Sink, Kerry O'Donnell
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  ABSTRACT: Arguably more mycophiles hunt true morels (Morchella) during their brief fruiting season each spring in the northern hemisphere than any other wild edible fungus. Concerns about overharvesting by individual collectors and commercial enterprises make it essential that science-based management practices and conservation policies are developed to ensure thesustainability of commercial harvests and to protect and preserve morel species diversity. Therefore, the primary objectives of the present study were to: (i) investigate the utility of the ITS rDNA locus for identifying Morchella species, using phylogenetic species previously inferred from multilocus DNA sequence data as a reference; and (ii) clarify insufficiently identified sequences and determine whether the named sequences in GenBank were identified correctly. To this end, we generated 553 Morchella ITS rDNA sequences and downloaded 312 additional ones generated by other researchers from GenBank using emerencia and analyzed them phylogenetically. Three major findings emerged: (i) ITS rDNA sequences were useful in identifying 48/62 (77.4%) of the known phylospecies; however, they failed to identify 12 of the22 species within the species-rich Elata Subclade and two closely related species in the Esculenta Clade; (ii) at least 66% of the named Morchella sequences in GenBank are misidentified; and (iii) ITS rDNA sequences of up to six putatively novel Morchella species were represented inGenBank. Recognizing the need for a dedicated Web-accessible reference database to facilitate the rapid identification of known and novel species, we constructed Morchella MLST(http://www.cbs.knaw.nl/morchella/), which can be queried with ITS rDNA sequences and those of the four other genes used in our prior multilocus molecular systematic studies of thischarismatic genus.
  Mycologia 07/2012; · 2.03 Impact Factor
• Article: Multigene molecular phylogenetics reveals true morels (Morchella) are especially species-rich in China.

  Xi-Hui Du, Qi Zhao, Kerry O'Donnell, Alejandro P Rooney, Zhu L Yang
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  ABSTRACT: The phylogenetic diversity of true morels (Morchella) in China was estimated by initially analyzing nuclear ribosomal internal transcribed spacer (ITS) rDNA sequences from 361 specimens collected in 21 provinces during the 2003-2011 growing seasons, together with six collections obtained on loan from three Chinese herbaria. Based on the results of this preliminary screen, 40 Esculenta Clade (yellow morels) and 30 Elata Clade (black morels) were chosen to represent the full range of phylogenetic diversity sampled. To investigate their species limits, we generated DNA sequences from portions of three protein-coding genes (RPB1, RPB2 and EF-1α) and domains D1 and D2 of the nuclear large subunit (LSU) rDNA for all 70 collections. To fully assess evolutionary relationships, previously published multilocus DNA sequence data representing all known Morchella species was included in this study. Phylogenetic analyses employing maximum parsimony and maximum likelihood frameworks resolved 30 species in China compared with 22 in Europe and 19 within North America. Eleven novel phylogenetically distinct species were discovered in China, including two species within the Elata Clade and nine within the Esculenta Clade. Of the 30 species in China, 20 appear to be endemic, nine were also represented in Europe, and four putatively fire-adapted species have disjunct distributions in China, Europe and western North America. Although the diversification time estimates place the Esculenta Clade in China as early as the late Cretaceous and the Elata Clade by the early Oligocene, 27 of the 30 species evolved between the middle Miocene 12Mya and present.
  Fungal Genetics and Biology 04/2012; 49(6):455-69. · 3.74 Impact Factor