April 21, 2020  |  

Hybrid Sequencing of Full-Length cDNA Transcripts of the Medicinal Plant Scutellaria baicalensis.

Scutellaria baicalensis is a well-known medicinal plant that produces biologically active flavonoids, such as baicalin, baicalein, and wogonin. Pharmacological studies have shown that these compounds have anti-inflammatory, anti-bacterial, and anti-cancer activities. Therefore, it is of great significance to investigate the genetic information of S. baicalensis, particularly the genes related to the biosynthetic pathways of these compounds. Here, we constructed the full-length transcriptome of S. baicalensis using a hybrid sequencing strategy and acquired 338,136 full-length sequences, accounting for 93.3% of the total reads. After the removal of redundancy and correction with Illumina short reads, 75,785 nonredundant transcripts were generated, among which approximately 98% were annotated with significant hits in the protein databases, and 11,135 sequences were classified as lncRNAs. Differentially expressed gene (DEG) analysis showed that most of the genes related to flavonoid biosynthesis were highly expressed in the roots, consistent with previous reports that the flavonoids were mainly synthesized and accumulated in the roots of S. baicalensis. By constructing unique transcription models, a total of 44,071 alternative splicing (AS) events were identified, with intron retention (IR) accounting for the highest proportion (44.5%). A total of 94 AS events were present in five key genes related to flavonoid biosynthesis, suggesting that AS may play important roles in the regulation of flavonoid biosynthesis in S. baicalensis. This study provided a large number of highly accurate full-length transcripts, which represents a valuable genetic resource for further research of the molecular biology of S. baicalensis, such as the development, breeding, and biosynthesis of active ingredients.


April 21, 2020  |  

Dynamic Changes in Metabolite Accumulation and the Transcriptome during Leaf Growth and Development in Eucommia ulmoides.

Eucommia ulmoides Oliver is widely distributed in China. This species has been used mainly in medicine due to the high concentration of chlorogenic acid (CGA), flavonoids, lignans, and other compounds in the leaves and barks. However, the categories of metabolites, dynamic changes in metabolite accumulation and overall molecular mechanisms involved in metabolite biosynthesis during E. ulmoides leaf growth and development remain unknown. Here, a total of 515 analytes, including 127 flavonoids, 46 organic acids, 44 amino acid derivatives, 9 phenolamides, and 16 vitamins, were identified from four E. ulmoides samples using ultraperformance liquid chromatography-mass spectrometry (UPLC-MS) (for widely targeted metabolites). The accumulation of most flavonoids peaked in growing leaves, followed by old leaves. UPLC-MS analysis indicated that CGA accumulation increased steadily to a high concentration during leaf growth and development, and rutin showed a high accumulation level in leaf buds and growing leaves. Based on single-molecule long-read sequencing technology, 69,020 transcripts and 2880 novel loci were identified in E. ulmoides. Expression analysis indicated that isoforms in the flavonoid biosynthetic pathway and flavonoid metabolic pathway were highly expressed in growing leaves and old leaves. Co-expression network analysis suggested a potential direct link between the flavonoid and phenylpropanoid biosynthetic pathways via the regulation of transcription factors, including MYB (v-myb avian myeloblastosis viral oncogene homolog) and bHLH (basic/helix-loop-helix). Our study predicts dynamic metabolic models during leaf growth and development and will support further molecular biological studies of metabolite biosynthesis in E. ulmoides. In addition, our results significantly improve the annotation of the E. ulmoides genome.


April 21, 2020  |  

Complete chloroplast genome sequences of Kaempferia galanga and Kaempferia elegans: Molecular structures and comparative analysis.

Kaempferia galanga and Kaempferia elegans, which belong to the genus Kaempferia family Zingiberaceae, are used as valuable herbal medicine and ornamental plants, respectively. The chloroplast genomes have been used for molecular markers, species identification and phylogenetic studies. In this study, the complete chloroplast genome sequences of K. galanga and K. elegans are reported. Results show that the complete chloroplast genome of K. galanga is 163,811 bp long, having a quadripartite structure with large single copy (LSC) of 88,405 bp and a small single copy (SSC) of 15,812 bp separated by inverted repeats (IRs) of 29,797 bp. Similarly, the complete chloroplast genome of K. elegans is 163,555 bp long, having a quadripartite structure in which IRs of 29,773 bp length separates 88,020 bp of LSC and 15,989 bp of SSC. A total of 111 genes in K. galanga and 113 genes in K. elegans comprised 79 protein-coding genes and 4 ribosomal RNA (rRNA) genes, as well as 28 and 30 transfer RNA (tRNA) genes in K. galanga and K. elegans, respectively. The gene order, GC content and orientation of the two Kaempferia chloroplast genomes exhibited high similarity. The location and distribution of simple sequence repeats (SSRs) and long repeat sequences were determined. Eight highly variable regions between the two Kaempferia species were identified and 643 mutation events, including 536 single-nucleotide polymorphisms (SNPs) and 107 insertion/deletions (indels), were accurately located. Sequence divergences of the whole chloroplast genomes were calculated among related Zingiberaceae species. The phylogenetic analysis based on SNPs among eleven species strongly supported that K. galanga and K. elegans formed a cluster within Zingiberaceae. This study identified the unique characteristics of the entire K. galanga and K. elegans chloroplast genomes that contribute to our understanding of the chloroplast DNA evolution within Zingiberaceae species. It provides valuable information for phylogenetic analysis and species identification within genus Kaempferia.


April 21, 2020  |  

Comprehensive transcriptome analysis reveals genes potentially involved in isoflavone biosynthesis in Pueraria thomsonii Benth.

Pueraria thomsonii Benth is an important medicinal plant. Transcriptome sequencing, unigene assembly, the annotation of transcripts and the study of gene expression profiles play vital roles in gene function research. However, the full-length transcriptome of P. thomsonii remains unknown. Here, we obtained 44,339 nonredundant transcripts of P. thomsonii by using the PacBio RS II Isoform and Illumina sequencing platforms, of which 43,195 were annotated genes. Compared with the expression levels in the plant roots, those of transcripts with a |fold change| = 4 and FDR < 0.01 in the leaves or stems were assigned as differentially expressed transcripts (DETs). In total, we found 9,225 DETs, 32 of which came from structural genes that were potentially involved in isoflavone biosynthesis. The expression profiles of 8 structural genes from the RNA-Seq data were validated by qRT-PCR. We identified 437 transcription factors (TFs) that were positively or negatively correlated with at least 1 of the structural genes involved in isoflavone biosynthesis using Pearson correlation coefficients (r) (r > 0.8 or r < -0.8). We also identified a total of 32 microRNAs (miRNAs), which targeted 805 transcripts. These miRNAs caused enriched function in 'ATP binding', 'defense response', 'ADP binding', and 'signal transduction'. Interestingly, MIR156a potentially promoted isoflavone biosynthesis by repressing SBP, and MIR319 promoted isoflavone biosynthesis by repressing TCP and HB-HD-ZIP. Finally, we identified 2,690 alternative splicing events, including that of the structural genes of trans-cinnamate 4-monooxygenase and pullulanase, which are potentially involved in the biosynthesis of isoflavone and starch, respectively, and of three TFs potentially involved in isoflavone biosynthesis. Together, these results provide us with comprehensive insight into the gene expression and regulation of P. thomsonii.


April 21, 2020  |  

The Reference Genome Sequence of Scutellaria baicalensis Provides Insights into the Evolution of Wogonin Biosynthesis.

Scutellaria baicalensis Georgi is important in Chinese traditional medicine where preparations of dried roots, “Huang Qin,” are used for liver and lung complaints and as complementary cancer treatments. We report a high-quality reference genome sequence for S. baicalensis where 93% of the 408.14-Mb genome has been assembled into nine pseudochromosomes with a super-N50 of 33.2 Mb. Comparison of this sequence with those of closely related species in the order Lamiales, Sesamum indicum and Salvia splendens, revealed that a specialized metabolic pathway for the synthesis of 4′-deoxyflavone bioactives evolved in the genus Scutellaria. We found that the gene encoding a specific cinnamate coenzyme A ligase likely obtained its new function following recent mutations, and that four genes encoding enzymes in the 4′-deoxyflavone pathway are present as tandem repeats in the genome of S. baicalensis. Further analyses revealed that gene duplications, segmental duplication, gene amplification, and point mutations coupled to gene neo- and subfunctionalizations were involved in the evolution of 4′-deoxyflavone synthesis in the genus Scutellaria. Our study not only provides significant insight into the evolution of specific flavone biosynthetic pathways in the mint family, Lamiaceae, but also will facilitate the development of tools for enhancing bioactive productivity by metabolic engineering in microbes or by molecular breeding in plants. The reference genome of S. baicalensis is also useful for improving the genome assemblies for other members of the mint family and offers an important foundation for decoding the synthetic pathways of bioactive compounds in medicinal plants.Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.


April 21, 2020  |  

The genome of the medicinal plant Andrographis paniculata provides insight into the biosynthesis of the bioactive diterpenoid neoandrographolide.

Andrographis paniculata is a herbaceous dicot plant widely used for its anti-inflammatory and anti-viral properties across its distribution in China, India and other Southeast Asian countries. A. paniculata was used as a crucial therapeutic treatment during the influenza epidemic of 1919 in India, and is still used for the treatment of infectious disease in China. A. paniculata produces large quantities of the anti-inflammatory diterpenoid lactones andrographolide and neoandrographolide, and their analogs, which are touted to be the next generation of natural anti-inflammatory medicines for lung diseases, hepatitis, neurodegenerative disorders, autoimmune disorders and inflammatory skin diseases. Here, we report a chromosome-scale A. paniculata genome sequence of 269 Mb that was assembled by Illumina short reads, PacBio long reads and high-confidence (Hi-C) data. Gene annotation predicted 25 428 protein-coding genes. In order to decipher the genetic underpinning of diterpenoid biosynthesis, transcriptome data from seedlings elicited with methyl jasmonate were also obtained, which enabled the identification of genes encoding diterpenoid synthases, cytochrome P450 monooxygenases, 2-oxoglutarate-dependent dioxygenases and UDP-dependent glycosyltransferases potentially involved in diterpenoid lactone biosynthesis. We further carried out functional characterization of pairs of class-I and -II diterpene synthases, revealing the ability to produce diversified labdane-related diterpene scaffolds. In addition, a glycosyltransferase able to catalyze O-linked glucosylation of andrograpanin, yielding the major active product neoandrographolide, was also identified. Thus, our results demonstrate the utility of the combined genomic and transcriptomic data set generated here for the investigation of the production of the bioactive diterpenoid lactone constituents of the important medicinal herb A. paniculata. © 2018 The Authors The Plant Journal © 2018 John Wiley & Sons Ltd.


April 21, 2020  |  

Stout camphor tree genome fills gaps in understanding of flowering plant genome evolution.

We present reference-quality genome assembly and annotation for the stout camphor tree (Cinnamomum kanehirae (Laurales, Lauraceae)), the first sequenced member of the Magnoliidae comprising four orders (Laurales, Magnoliales, Canellales and Piperales) and over 9,000 species. Phylogenomic analysis of 13 representative seed plant genomes indicates that magnoliid and eudicot lineages share more recent common ancestry than monocots. Two whole-genome duplication events were inferred within the magnoliid lineage: one before divergence of Laurales and Magnoliales and the other within the Lauraceae. Small-scale segmental duplications and tandem duplications also contributed to innovation in the evolutionary history of Cinnamomum. For example, expansion of the terpenoid synthase gene subfamilies within the Laurales spawned the diversity of Cinnamomum monoterpenes and sesquiterpenes.


April 21, 2020  |  

Genome-wide analysis of methyl jasmonate-regulated isoform expression in the medicinal plant Andrographis paniculata

Alternative splicing can increase the complexity of the transcriptome and proteome. The most common mechanism of alternative splicing in plants is intron retention (IR), and the expression levels of IR isoforms can be differentially regulated when facing abiotic stress. The full-length transcriptome of the medicinal plant Andrographis paniculata was sequenced using both Illumina- and SMRT-based RNA-seq and a total of 4846 IR isoforms were identified. The expression levels of 310/296 IR isoforms were up-regulated, and 629/659 IR isoforms were down-regulated at 24?h/48?h after methyl jasmonate (MeJA) treatment, respectively. In the (E,E,E)-geranylgeranyl diphosphate (GGPP) biosynthesis pathway which contributes to the andrographolide biosynthesis, eight genes were alternatively spliced, resulting in a total of 25 isoforms, of which 12 are IR isoforms. After MeJA treatment, four of these IR isoforms showed significant differential expression. RT-PCR and qRT-PCR experiments confirmed the existence of five IR isoforms. This research deepens our understanding of the A. paniculata transcriptome and can assist in the future study of andrographolide biosynthesis.


April 21, 2020  |  

Hypoglycemic activity and gut microbiota regulation of a novel polysaccharide from Grifola frondosa in type 2 diabetic mice.

GFP-N, a novel heteropolysaccharide with a molecular weight of 1.26?×?107?Da, was isolated from maitake mushroom and purified by anion-exchange chromatography on a DEAE cellulose-52 column and gel-filtration chromatography on a Sephadex G-100 column. Its structure was characterized by Fourier transform infrared spectroscopy and one-dimensional (1H- and 13C-) NMR spectra, 1H1H correlation spectroscopy, and 1H13C heteronuclear single-quantum coherence spectroscopy. The structure of GFP-N consisted of L-arabinose, D-mannose and D-glucose and mainly contained three kinds of linkage type units as ?2,6)-a-D-Manp-(1???4, a-L-Araf-C1?, and ?3,6)-ß-D-Glcp-(1???. GFP-N could activate insulin receptor substrate 1, phosphatidylinositol-3-kinase, and glucose transporter 4 and inhibit c-Jun N-terminal kinase 1/2 for hypoglycemic effects in diabetic mouse livers. This is also the first report of the regulatory efficacy of Grifola frondosa polysaccharide on intestinal microflora in vivo using single-molecule real-time sequencing. These results indicated that polysaccharide from maitake mushroom could be as an enhancer to improve type 2 diabetes and a healthy food option to help regulate gut microbiota in diabetic individuals. Copyright © 2019 Elsevier Ltd. All rights reserved.


April 21, 2020  |  

The complete mitochondrial genome sequence of Schisandra chinensis (Austrobaileyales: Schisandraceae)

Chinese magnolia vine (Schisandra chinensis) is an economically important oriental medicinal plant that belongs to the Schisandraceae family. The complete mitochondrial genome sequence of S. chinensis was 946,141bp in length. A total of 45 genes was annotated, including 30 protein-coding genes, 12 tRNA genes, and 3 rRNA genes. A phylogenetic tree based on the mitochondrial genome demonstrated that S. chinensis was most closely related to Schisandra sphenanthera of the Schisandraceae family.


April 21, 2020  |  

High Quality Draft Genome of Arogyapacha (Trichopus zeylanicus), an Important Medicinal Plant Endemic to Western Ghats of India.

Arogyapacha, the local name of Trichopus zeylanicus, is a rare, indigenous medicinal plant of India. This plant is famous for its traditional use as an instant energy stimulant. So far, no genomic resource is available for this important plant and hence its metabolic pathways are poorly understood. Here, we report on a high-quality draft assembly of approximately 713.4 Mb genome of T. zeylanicus, first draft genome from the genus Trichopus The assembly was generated in a hybrid approach using Illumina short-reads and Pacbio longer-reads. The total assembly comprised of 22601 scaffolds with an N50 value of 433.3 Kb. We predicted 34452 protein coding genes in T. zeylanicus genome and found that a significant portion of these predicted genes were associated with various secondary metabolite biosynthetic pathways. Comparative genome analysis revealed extensive gene collinearity between T. zeylanicus and its closely related plant species. The present genome and annotation data provide an essential resource to speed-up the research on secondary metabolism, breeding and molecular evolution of T. zeylanicus. Copyright © 2019 Chellappan et al.


April 21, 2020  |  

A physical and genetic map of Cannabis sativa identifies extensive rearrangements at the THC/CBD acid synthase loci.

Cannabis sativa is widely cultivated for medicinal, food, industrial, and recreational use, but much remains unknown regarding its genetics, including the molecular determinants of cannabinoid content. Here, we describe a combined physical and genetic map derived from a cross between the drug-type strain Purple Kush and the hemp variety “Finola.” The map reveals that cannabinoid biosynthesis genes are generally unlinked but that aromatic prenyltransferase (AP), which produces the substrate for THCA and CBDA synthases (THCAS and CBDAS), is tightly linked to a known marker for total cannabinoid content. We further identify the gene encoding CBCA synthase (CBCAS) and characterize its catalytic activity, providing insight into how cannabinoid diversity arises in cannabis. THCAS and CBDAS (which determine the drug vs. hemp chemotype) are contained within large (>250 kb) retrotransposon-rich regions that are highly nonhomologous between drug- and hemp-type alleles and are furthermore embedded within ~40 Mb of minimally recombining repetitive DNA. The chromosome structures are similar to those in grains such as wheat, with recombination focused in gene-rich, repeat-depleted regions near chromosome ends. The physical and genetic map should facilitate further dissection of genetic and molecular mechanisms in this commercially and medically important plant. © 2019 Laverty et al.; Published by Cold Spring Harbor Laboratory Press.


April 21, 2020  |  

Chloroplast genome of Dalbergia cochinchinensis (Fabaceae), a rare and Endangered rosewood species in Southeast Asia

Dalbergia cochinchinensis is an tree species in Southeast Asia, its wood and wood products are incred- ibly valuable and are also of important medicinal value. In this study, its chloroplast genome was char- acterized using next generation Illumina pair-end and Pacbio sequencing dataset. The whole genome was 156,576bp in length and contains a pair of 25,682bp inverted repeat regions, which were sepa- rated by a large single copy region and a small single copy region of 85,886 and 19,326bp in length, respectively. The cp genome contained 111 genes, including 77 protein-coding genes, 30 tRNAs and 4 rRNAs. A neighbor-joining phylogenetic analysis suggested D. cochinchinensis, which belonged to Dalbergieae, Fabaceae.


April 21, 2020  |  

A global survey of full-length transcriptome of Ginkgo biloba reveals transcript variants involved in flavonoid biosynthesis

Ginkgo biloba, which contains flavonoids as bioactive components, is widely used in traditional Chinese medicine. Increasing the flavonoid production of medicinal plants through genetic engineering generally focuses on the key genes involved in flavonoid biosynthesis. However, the molecular mechanisms underlying such biosynthesis are not yet well understood. To understand these mechanisms, a combination of second-generation sequencing (SGS) and single-molecule real-time (SMRT) sequencing was applied to G. biloba. Eight tissues were sampled for SMRT sequencing to generate a high-quality, full-length transcriptome database. From 23.36 Gb clean reads, 12,954 alternative polyadenylation events, 12,290 alternative splicing events, 929 fusion transcripts, 2,286 novel transcripts, and 1,270 lncRNAs were predicted by removing redundant reads. Further studies reveal that 7 AS, 5 lncRNA, and 6 fusion gene events were identified in flavonoid biosynthesis. A total of 12 gene modules were revealed to be involved in flavonoid metabolism structural genes and transcription factors by constructing co-expression networks. Weighted gene coexpression network analysis (WGCNA) analysis reveals that some hub genes operate during the biosynthesis by identifying transcription factors (TFs) and structure genes. Seven key hub genes were also identified by analyzing the correlation between gene expression level and flavonoids content. The results highlight the importance of SMRT sequencing of the full-length transcriptome in improving genome annotation and elucidating the gene regulation of flavonoid biosynthesis in G. biloba by providing a comprehensive set of reference transcripts.


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