Study protocol for artificial intelligence-assisted sponge cytology as pre-endoscopy screening for early esophegeal squmaous epithelial lesions in China.

BACKGROUND: Endoscopic screening is the widely accepted screening strategy for esophageal squmaous cell carcinoma (ESCC). However, massive endoscopic screening is expensive and not cost-efficient, and novel pre-endoscopy detection used as a preliminary screening method arouses new concerns. We are planning to launch an artificial intelligence (AI) assisted sponge cytology for detecting esophageal squmaous high-grade intraepithelial neoplasia (HGIN) and above lesions. The aim of this trail is to investigate the efficiency of AI-assisted sponge cytology in population-based screening of early esophageal squmaous epithelial lesions. METHODS: The study will be prospectively conducted in five regions with a high prevalence of ESCC. AI-assisted sponge cytology and endoscopic examination will be sequentially performed. Based on our previous data, at least 864 patients with esophageal HGIN and above lesions are needed to achieve enough statistical power. And, a calculated 112,500 individuals with high risks of ESCC will be recruited. In the first stage, each 24,000 participants who meet the inclusion criteria will be recruited on a voluntary basis. Setting pathological results as standard reference, diagnostic threshold and according performance of AI-assisted detection will be evaluated. A prediction model will be constructed by co-analyzing cytological results and relevant risk factors. Then, an external validation cohort will be used for validation of the model efficiency. Also, cost-efficiency analysis will be performed. This study protocol was registered on chineseclinicaltrial.gov (ChiCTR1900028524). DISCUSSION: Our study will determine whether this AI-assisted sponge cytology can be used as an effective pre-endoscopy detection tool for large-scale screening for ESCC in high-risk areas.

Histone H2B Monoubiquitination Mediated by HISTONE MONOUBIQUITINATION1 and HISTONE MONOUBIQUITINATION2 Is Involved in Anther Development by Regulating Tapetum Degradation-Related Genes in Rice.

Histone H2B monoubiquitination (H2Bub1) is an important regulatory mechanism in eukaryotic gene transcription and is essential for normal plant development. However, the function of H2Bub1 in reproductive development remains elusive. Here, we report rice (Oryza sativa) HISTONE MONOUBIQUITINATION1 (OsHUB1) and OsHUB2, the homologs of Arabidopsis (Arabidopsis thaliana) HUB1 and HUB2 proteins, which function as E3 ligases in H2Bub1, are involved in late anther development in rice. oshub mutants exhibit abnormal tapetum development and aborted pollen in postmeiotic anthers. Knockout of OsHUB1 or OsHUB2 results in the loss of H2Bub1 and a reduction in the levels of dimethylated lysine-4 on histone 3 (H3K4me2). Anther transcriptome analysis revealed that several key tapetum degradation-related genes including OsC4, rice Cysteine Protease1 (OsCP1), and Undeveloped Tapetum1 (UDT1) were down-regulated in the mutants. Further, chromatin immunoprecipitation assays demonstrate that H2Bub1 directly targets OsC4, OsCP1, and UDT1 genes, and enrichment of H2Bub1 and H3K4me2 in the targets is consistent to some degree. Our studies suggest that histone H2B monoubiquitination, mediated by OsHUB1 and OsHUB2, is an important epigenetic modification that in concert with H3K4me2, modulates transcriptional regulation of anther development in rice.

Arabidopsis paired amphipathic helix proteins SNL1 and SNL2 redundantly regulate primary seed dormancy via abscisic acid-ethylene antagonism mediated by histone deacetylation.

Histone (de)acetylation is a highly conserved chromatin modification that is vital for development and growth. In this study, we identified a role in seed dormancy for two members of the histone deacetylation complex in Arabidopsis thaliana, SIN3-LIKE1 (SNL1) and SNL2. The double mutant snl1 snl2 shows reduced dormancy and hypersensitivity to the histone deacetylase inhibitors trichostatin A and diallyl disulfide compared with the wild type. SNL1 interacts with HISTONE DEACETYLASE19 in vitro and in planta, and loss-of-function mutants of SNL1 and SNL2 show increased acetylation levels of histone 3 lysine 9/18 (H3K9/18) and H3K14. Moreover, SNL1 and SNL2 regulate key genes involved in the ethylene and abscisic acid (ABA) pathways by decreasing their histone acetylation levels. Taken together, we showed that SNL1 and SNL2 regulate seed dormancy by mediating the ABA-ethylene antagonism in Arabidopsis. SNL1 and SNL2 could represent a cross-link point of the ABA and ethylene pathways in the regulation of seed dormancy.

[Transcriptome characterization of Ephedra sinica with 454 ESTs].

Using the latest 454 GS FLX platform and Titanium regent, a substantial expressed sequence tag (ESTs) dataset of Ephedra sinica was produced, and the profile of gene expression and function gene of which were investigated. A total of 48 389 reads with an average length of 373 bp were generated. These 454 reads were assembled into 18 801 unigenes, which were all 454 sequencing identified. A total number of 10 531 unigenes(56.0%) were annotated using BLAST searches (E-value≤1×10⁻5) against the Nr, Nt, TAIR, SwissProt and KEGG databases. With respect to genes related to ephedrine biosynthesis, 19 unigenes(encoding 9 enzymes) were found. A total of 97 putative genes encoding cytochrome P450s were also discovered. Data presented in this study will provide an important resource for the scientific community that is interested in the functional genomics and secondary metabolism of E. sinica.

Knockout of AtDjB1, a J-domain protein from Arabidopsis thaliana, alters plant responses to osmotic stress and abscisic acid.

AtDjB1 is a member of the Arabidopsis thaliana J-protein family. AtDjB1 is targeted to the mitochondria and plays a crucial role in A. thaliana heat and oxidative stress resistance. Herein, the role of AtDjB1 in adapting to saline and drought stress was studied in A. thaliana. AtDjB1 expression was induced through salinity, dehydration and abscisic acid (ABA) in young seedlings. Reverse genetic analyses indicate that AtDjB1 is a negative regulator in plant osmotic stress tolerance. Further, AtDjB1 knockout mutant plants (atj1-1) exhibited greater ABA sensitivity compared with the wild-type (WT) plants and the mutant lines with a rescued AtDjB1 gene. AtDjB1 gene knockout also altered the expression of several ABA-responsive genes, which suggests that AtDjB1 is involved in osmotic stress tolerance through its effects on ABA signaling pathways. Moreover, atj1-1 plants exhibited higher glucose levels and greater glucose sensitivity in the post-germination development stage. Applying glucose promoted an ABA response in seedlings, and the promotion was more evident in atj1-1 than WT seedlings. Taken together, higher glucose levels in atj1-1 plants are likely responsible for the greater ABA sensitivity and increased osmotic stress tolerance.

Processing and Properties of Single-Crystal Copper Wire.

The effects of drawing parameters and annealing process on the properties and microstructure of single crystal copper wire are studied using a wire-drawing machine, heat-treatment equipment, microcomputer-controlled electronic universal tester, resistance tester, and scanning electron microscope. The results show that, after drawing the single-crystal copper wire with a single-pass deformation of 14%, the grains elongate along the tensile direction, tensile strength increases from 500.83 MPa to 615.5 Mpa, and resistivity changes from 1.745 × 10-8 Ω·m to 1.732 × 10-8 Ω·m. After drawing at a drawing rate of 500 m/min, the degree of grain refinement increases and tensile strength increases from 615.5 Mpa to 660.26 Mpa. When a copper wire of Φ0.08 mm is annealed, its tensile strength decreases from 660.26 Mpa to 224.7 Mpa, and elongation increases from 1.494% to 19.87% when the annealing temperature increases to 400 °C. When the annealing temperature increases to 550 °C, the tensile strength and elongation decrease to 214.4 MPa and 12.18%, respectively.

Research Status of Manufacturing Technology of Tungsten Alloy Wire.

In light of the fact that tungsten wire is gradually replacing high-carbon steel wire as a diamond cutting line, it is particularly important to study tungsten alloy wire with better strength and performance. According to this paper, in addition to various technological factors (powder preparation, press forming, sintering, rolling, rotary forging, annealing, wire drawing, etc.), the main factors affecting the properties of the tungsten alloy wire are the composition of the tungsten alloy, the shape and size of the powder, etc. Combined with the research results in recent years, this paper summarizes the effects of changing the composition of tungsten materials and improving the processing technology on the microstructure and mechanical properties of tungsten and its alloys and points out the development direction and trend of tungsten and its alloy wires in the future.

The Arabidopsis J-protein AtDjB1 facilitates thermotolerance by protecting cells against heat-induced oxidative damage.

AtDjB1 belongs to the J-protein family in Arabidopsis thaliana. Its biological functions in plants are largely unknown. In this study, we examined the roles of AtDjB1 in resisting heat and oxidative stresses in A. thaliana using reverse genetic analysis. AtDjB1 knockout plants (atj1-1) were more sensitive to heat stress than wildtype plants, and displayed decreased concentrations of ascorbate (ASC), and increased concentrations of hydrogen peroxide (H(2)O(2)) and oxidative products after heat shock. Application of H(2)O(2) accelerated cell death and decreased seedling viability in atj1-1. Exogenous ASC conferred much greater thermotolerance in atj1-1 than in wildtype plants, suggesting that a lower concentration of ASC in atj1-1 could be responsible for the increased concentration of H(2)O(2) and decreased thermotolerance. Furthermore, AtDjB1 was found to localize to mitochondria, directly interact with a mitochondrial heat-shock protein 70 (mtHSC70-1), and stimulate ATPase activity of mtHSC70-1. AtDjB1 knockout led to the accumulation of cellular ATP and decreased seedling respiration, indicating that AtDjB1 modulated the ASC concentration probably through affecting the function of mitochondria. Taken together, these results suggest that AtDjB1 plays a crucial role in maintaining redox homeostasis, and facilitates thermotolerance by protecting cells against heat-induced oxidative damage.

Pyrosequencing of the Camptotheca acuminata transcriptome reveals putative genes involved in camptothecin biosynthesis and transport.

BACKGROUND: Camptotheca acuminata is a Nyssaceae plant, often called the "happy tree", which is indigenous in Southern China. C. acuminata produces the terpenoid indole alkaloid, camptothecin (CPT), which exhibits clinical effects in various cancer treatments. Despite its importance, little is known about the transcriptome of C. acuminata and the mechanism of CPT biosynthesis, as only few nucleotide sequences are included in the GenBank database. RESULTS: From a constructed cDNA library of young C. acuminata leaves, a total of 30,358 unigenes, with an average length of 403 bp, were obtained after assembly of 74,858 high quality reads using GS De Novo assembler software. Through functional annotation, a total of 21,213 unigenes were annotated at least once against the NCBI nucleotide (Nt), non-redundant protein (Nr), Uniprot/SwissProt, Kyoto Encyclopedia of Genes and Genomes (KEGG), and Arabidopsis thaliana proteome (TAIR) databases. Further analysis identified 521 ESTs representing 20 enzyme genes that are involved in the backbone of the CPT biosynthetic pathway in the library. Three putative genes in the upstream pathway, including genes for geraniol-10-hydroxylase (CaPG10H), secologanin synthase (CaPSCS), and strictosidine synthase (CaPSTR) were cloned and analyzed. The expression level of the three genes was also detected using qRT-PCR in C. acuminata. With respect to the branch pathway of CPT synthesis, six cytochrome P450s transcripts were selected as candidate transcripts by detection of transcript expression in different tissues using qRT-PCR. In addition, one glucosidase gene was identified that might participate in CPT biosynthesis. For CPT transport, three of 21 transcripts for multidrug resistance protein (MDR) transporters were also screened from the dataset by their annotation result and gene expression analysis. CONCLUSION: This study produced a large amount of transcriptome data from C. acuminata by 454 pyrosequencing. According to EST annotation, catalytic features prediction, and expression analysis, novel putative transcripts involved in CPT biosynthesis and transport were discovered in C. acuminata. This study will facilitate further identification of key enzymes and transporter genes in C. acuminata.

Analysis of the transcriptome of Panax notoginseng root uncovers putative triterpene saponin-biosynthetic genes and genetic markers.

BACKGROUND: Panax notoginseng (Burk) F.H. Chen is important medicinal plant of the Araliacease family. Triterpene saponins are the bioactive constituents in P. notoginseng. However, available genomic information regarding this plant is limited. Moreover, details of triterpene saponin biosynthesis in the Panax species are largely unknown. RESULTS: Using the 454 pyrosequencing technology, a one-quarter GS FLX titanium run resulted in 188,185 reads with an average length of 410 bases for P. notoginseng root. These reads were processed and assembled by 454 GS De Novo Assembler software into 30,852 unique sequences. A total of 70.2% of unique sequences were annotated by Basic Local Alignment Search Tool (BLAST) similarity searches against public sequence databases. The Kyoto Encyclopedia of Genes and Genomes (KEGG) assignment discovered 41 unique sequences representing 11 genes involved in triterpene saponin backbone biosynthesis in the 454-EST dataset. In particular, the transcript encoding dammarenediol synthase (DS), which is the first committed enzyme in the biosynthetic pathway of major triterpene saponins, is highly expressed in the root of four-year-old P. notoginseng. It is worth emphasizing that the candidate cytochrome P450 (Pn02132 and Pn00158) and UDP-glycosyltransferase (Pn00082) gene most likely to be involved in hydroxylation or glycosylation of aglycones for triterpene saponin biosynthesis were discovered from 174 cytochrome P450s and 242 glycosyltransferases by phylogenetic analysis, respectively. Putative transcription factors were detected in 906 unique sequences, including Myb, homeobox, WRKY, basic helix-loop-helix (bHLH), and other family proteins. Additionally, a total of 2,772 simple sequence repeat (SSR) were identified from 2,361 unique sequences, of which, di-nucleotide motifs were the most abundant motif. CONCLUSION: This study is the first to present a large-scale EST dataset for P. notoginseng root acquired by next-generation sequencing (NGS) technology. The candidate genes involved in triterpene saponin biosynthesis, including the putative CYP450s and UGTs, were obtained in this study. Additionally, the identification of SSRs provided plenty of genetic makers for molecular breeding and genetics applications in this species. These data will provide information on gene discovery, transcriptional regulation and marker-assisted selection for P. notoginseng. The dataset establishes an important foundation for the study with the purpose of ensuring adequate drug resources for this species.

Transcriptome analysis of Taxus cuspidata needles based on 454 pyrosequencing.

Taxus species are highly valued as renewable resources for the production of Taxol. Despite the commercial and medicinal importance of Taxus, little genomic information is available for yew species, and Taxol biosynthesis still needs to be fully elucidated. In this study, 454 pyrosequencing technology was employed to produce an expressed sequence tag (EST) from the needles of Taxus cuspidata. In all, 81 148 high-quality reads from the needles of T. cuspidata were produced using Roche GS FLX Titanium. A total of 20,557 unique sequences were obtained, including 12 975 singletons and 7582 contigs. Approximately 14,095 unique sequences were annotated by a similarity search against five public databases. Gene ontology revealed 11,220 unique sequences that could be assigned to 45 vocabularies. In the Kyoto Encyclopedia of Genes and Genomes mapping, 2403 transcripts were established as associated with 3821 biochemical pathways. Enzymes in the plastidial 2-C-methyl-D-erythritol 4-phosphate pathway were well represented. Candidates of the putative genes of Taxol biosynthesis were revealed, including those in the remaining steps. In total, 291 transcripts were identified, representing putative homologues of transcription factors. Furthermore, 753 simple sequence repeat motifs, which are potential molecular markers for genetic application, were identified. These results provide the largest EST collections in TAXUS and will contribute to biosynthetic and biochemical studies that lead to drug improvement.

[Cloning and bioinformatic analysis of PqERF1 gene in Panax quinquefolius].

ERF family transcription factor (TF) represented ethylene-responsive protein which harbored a conserved AP2 domain. After searching the plant transcription factor database, a total of 75 unigenes was found which contained AP2 domain from the transcriptome dataset of Panax quinquefolius L. One unique sequence of ERF transcript, named as PqERF1, was cloned with entire open reading frame of 933 base pairs (bp). Protein prediction result indicated that the gene was localized in nucleus and had a conserved AP2 domain. PqERF1 gene could be induced by methyl jasmonate (MeJA) which was consistent to the inducing profile of triterpene ginsenosides. InterproScan prediction indicated that PqERF1 was probably a pathogenesis-related gene. Sequence alignment and phylogenetic analysis demonstrated PqERF1 was with high identity and had relative close relationship to the NtERF4 (Nicotiana tabacum), PhERF12 (Petunia x hybrida) and DcERF1 (Daucus carota) which was related to plant defense, regulation of secondary metabolism and the flower senescence respectively. Therefore, the gene was likely involved in regulation of secondary metabolism, plant defense and physical processes which would provide gene resource for further study on secondary metabolite synthesis and molecular breeding of P. quinquefolius.

De novo sequencing and analysis of the American ginseng root transcriptome using a GS FLX Titanium platform to discover putative genes involved in ginsenoside biosynthesis.

BACKGROUND: American ginseng (Panax quinquefolius L.) is one of the most widely used herbal remedies in the world. Its major bioactive constituents are the triterpene saponins known as ginsenosides. However, little is known about ginsenoside biosynthesis in American ginseng, especially the late steps of the pathway. RESULTS: In this study, a one-quarter 454 sequencing run produced 209,747 high-quality reads with an average sequence length of 427 bases. De novo assembly generated 31,088 unique sequences containing 16,592 contigs and 14,496 singletons. About 93.1% of the high-quality reads were assembled into contigs with an average 8-fold coverage. A total of 21,684 (69.8%) unique sequences were annotated by a BLAST similarity search against four public sequence databases, and 4,097 of the unique sequences were assigned to specific metabolic pathways by the Kyoto Encyclopedia of Genes and Genomes. Based on the bioinformatic analysis described above, we found all of the known enzymes involved in ginsenoside backbone synthesis, starting from acetyl-CoA via the isoprenoid pathway. Additionally, a total of 150 cytochrome P450 (CYP450) and 235 glycosyltransferase unique sequences were found in the 454 cDNA library, some of which encode enzymes responsible for the conversion of the ginsenoside backbone into the various ginsenosides. Finally, one CYP450 and four UDP-glycosyltransferases were selected as the candidates most likely to be involved in ginsenoside biosynthesis through a methyl jasmonate (MeJA) inducibility experiment and tissue-specific expression pattern analysis based on a real-time PCR assay. CONCLUSIONS: We demonstrated, with the assistance of the MeJA inducibility experiment and tissue-specific expression pattern analysis, that transcriptome analysis based on 454 pyrosequencing is a powerful tool for determining the genes encoding enzymes responsible for the biosynthesis of secondary metabolites in non-model plants. Additionally, the expressed sequence tags (ESTs) and unique sequences from this study provide an important resource for the scientific community that is interested in the molecular genetics and functional genomics of American ginseng.

EST analysis reveals putative genes involved in glycyrrhizin biosynthesis.

BACKGROUND: Glycyrrhiza uralensis is one of the most popular medicinal plants in the world and is also widely used in the flavoring of food and tobacco. Due to limited genomic and transcriptomic data, the biosynthetic pathway of glycyrrhizin, the major bioactive compound in G. uralensis, is currently unclear. Identification of candidate genes involved in the glycyrrhizin biosynthetic pathway will significantly contribute to the understanding of the biosynthetic and medicinal chemistry of this compound. RESULTS: We used the 454 GS FLX platform and Titanium regents to produce a substantial expressed sequence tag (EST) dataset from the vegetative organs of G. uralensis. A total of 59,219 ESTs with an average read length of 409 bp were generated. 454 ESTs were combined with the 50,666 G. uralensis ESTs in GenBank. The combined ESTs were assembled into 27,229 unique sequences (11,694 contigs and 15,535 singletons). A total of 20,437 unique gene elements representing approximately 10,000 independent transcripts were annotated using BLAST searches (e-value

Comparison of 454-ESTs from Huperzia serrata and Phlegmariurus carinatus reveals putative genes involved in lycopodium alkaloid biosynthesis and developmental regulation.

BACKGROUND: Plants of the Huperziaceae family, which comprise the two genera Huperzia and Phlegmariurus, produce various types of lycopodium alkaloids that are used to treat a number of human ailments, such as contusions, swellings and strains. Huperzine A, which belongs to the lycodine type of lycopodium alkaloids, has been used as an anti-Alzheimer's disease drug candidate. Despite their medical importance, little genomic or transcriptomic data are available for the members of this family. We used massive parallel pyrosequencing on the Roche 454-GS FLX Titanium platform to generate a substantial EST dataset for Huperzia serrata (H. serrata) and Phlegmariurus carinatus (P. carinatus) as representative members of the Huperzia and Phlegmariurus genera, respectively. H. serrata and P. carinatus are important plants for research on the biosynthesis of lycopodium alkaloids. We focused on gene discovery in the areas of bioactive compound biosynthesis and transcriptional regulation as well as genetic marker detection in these species. RESULTS: For H. serrata, 36,763 unique putative transcripts were generated from 140,930 reads totaling over 57,028,559 base pairs; for P. carinatus, 31,812 unique putative transcripts were generated from 79,920 reads totaling over 30,498,684 base pairs. Using BLASTX searches of public databases, 16,274 (44.3%) unique putative transcripts from H. serrata and 14,070 (44.2%) from P. carinatus were assigned to at least one protein. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) orthology annotations revealed that the functions of the unique putative transcripts from these two species cover a similarly broad set of molecular functions, biological processes and biochemical pathways.In particular, a total of 20 H. serrata candidate cytochrome P450 genes, which are more abundant in leaves than in roots and might be involved in lycopodium alkaloid biosynthesis, were found based on the comparison of H. serrata and P. carinatus 454-ESTs and real-time PCR analysis. Four unique putative CYP450 transcripts (Hs01891, Hs04010, Hs13557 and Hs00093) which are the most likely to be involved in the biosynthesis of lycopodium alkaloids were selected based on a phylogenetic analysis. Approximately 115 H. serrata and 98 P. carinatus unique putative transcripts associated with the biosynthesis of triterpenoids, alkaloids and flavones/flavonoids were located in the 454-EST datasets. Transcripts related to phytohormone biosynthesis and signal transduction as well as transcription factors were also obtained. In addition, we discovered 2,729 and 1,573 potential SSR-motif microsatellite loci in the H. serrata and P. carinatus 454-ESTs, respectively. CONCLUSIONS: The 454-EST resource allowed for the first large-scale acquisition of ESTs from H. serrata and P. carinatus, which are representative members of the Huperziaceae family. We discovered many genes likely to be involved in the biosynthesis of bioactive compounds and transcriptional regulation as well as a large number of potential microsatellite markers. These results constitute an essential resource for understanding the molecular basis of developmental regulation and secondary metabolite biosynthesis (especially that of lycopodium alkaloids) in the Huperziaceae, and they provide an overview of the genetic diversity of this family.

[Strategies of the study on herb genome program].

Herb Genome Program (HerbGP) includes a series of projects on whole genome sequencing (WGS) and post-genomics research of medicinal plants with unique secondary metabolism pathways or/and those of great medical and pharmaceutical importance. In this paper, we systematically discussed the strategy of HerbGP, from species selection, whole-genome sequencing, assembly and bioinformatics analysis, to postgenomics research. HerbGP will push study on Chinese traditional medicines into the front field of life science, by selecting a series of plants with unique secondary metabolism pathways as models and introducing "omics" methods into the research of these medicinal plants. HerbGP will provide great opportunities for China to be the leader in the basic research field of traditional Chinese medicine. HerbGP shall also have significant impacts on the R&D of natural medicines and the development of medicinal farming by analysis of secondary metabolic pathways and selection of cultivars with good agricultural traits.

Rhodium(III)-Catalyzed Meta-Selective C-H Alkenylation of Phenol Derivatives.

Rhodium(III)-catalyzed remote meta-selective-C-H alkenylation of phenol derivatives has been developed using a traceless organosilicon template as the directing group. This transformation proceeds smoothly with good yields and high meta-selectivities toward a series of phenol and alkene substrates. In addition, this protocol provides an effective strategy for late-stage transformations of various meta-alkenylated aromatic compounds.

Extensive pyrosequencing reveals frequent intra-genomic variations of internal transcribed spacer regions of nuclear ribosomal DNA.

BACKGROUND: Internal transcribed spacer of nuclear ribosomal DNA (nrDNA) is already one of the most popular phylogenetic and DNA barcoding markers. However, the existence of its multiple copies has complicated such usage and a detailed characterization of intra-genomic variations is critical to address such concerns. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we used sequence-tagged pyrosequencing and genome-wide analyses to characterize intra-genomic variations of internal transcribed spacer 2 (ITS2) regions from 178 plant species. We discovered that mutation of ITS2 is frequent, with a mean of 35 variants per species. And on average, three of the most abundant variants make up 91% of all ITS2 copies. Moreover, we found different congeneric species share identical variants in 13 genera. Interestingly, different species across different genera also share identical variants. In particular, one minor variant of ITS2 in Eleutherococcus giraldii was found identical to the ITS2 major variant of Panax ginseng, both from Araliaceae family. In addition, DNA barcoding gap analysis showed that the intra-genomic distances were markedly smaller than those of the intra-specific or inter-specific variants. When each of 5543 variants were examined for its species discrimination efficiency, a 97% success rate was obtained at the species level. CONCLUSIONS: Identification of identical ITS2 variants across intra-generic or inter-generic species revealed complex species evolutionary history, possibly, horizontal gene transfer and ancestral hybridization. Although intra-genomic multiple variants are frequently found within each genome, the usage of the major variants alone is sufficient for phylogeny construction and species determination in most cases. Furthermore, the inclusion of minor variants further improves the resolution of species identification.

Genome sequence of the model medicinal mushroom Ganoderma lucidum.

Ganoderma lucidum is a widely used medicinal macrofungus in traditional Chinese medicine that creates a diverse set of bioactive compounds. Here we report its 43.3-Mb genome, encoding 16,113 predicted genes, obtained using next-generation sequencing and optical mapping approaches. The sequence analysis reveals an impressive array of genes encoding cytochrome P450s (CYPs), transporters and regulatory proteins that cooperate in secondary metabolism. The genome also encodes one of the richest sets of wood degradation enzymes among all of the sequenced basidiomycetes. In all, 24 physical CYP gene clusters are identified. Moreover, 78 CYP genes are coexpressed with lanosterol synthase, and 16 of these show high similarity to fungal CYPs that specifically hydroxylate testosterone, suggesting their possible roles in triterpenoid biosynthesis. The elucidation of the G. lucidum genome makes this organism a potential model system for the study of secondary metabolic pathways and their regulation in medicinal fungi.