RNA-seq Analysis

Transcriptomics is one of the most popular topics in biology in recent times. Transcriptome sequencing (RNA-Seq) is a high-throughput, high-sensitivity, and high-resolution technique that can be used to study model and non-model organisms. Transcriptome sequencing is also an important method for studying the genomes of medicinal plants, a topic on which limited information is available. The study of medicinal plants through transcriptomics can help researchers analyze functional genes and regulatory mechanisms of medicinal plants and improve breeding selection and cultivation techniques. This article analyzes and compares the applications of transcriptome sequencing in medicinal plants over the past decade and briefly introduces the methods of transcriptome sequencing and analysis, their applications in medicinal plant research, and potential development trends. We will focus on the research and application progress of transcriptome sequencing in the following four areas: the mining of functional genes in medicinal plants, development of molecular markers, biosynthetic pathways of secondary metabolites, and developmental mechanisms of medicinal plants. Our review will provide ideas for the mining of functional genes of medicinal plants and breeding new varieties.

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Research Progress and Future Development Trends in Medicinal Plant Transcriptomics.

我们分析了在 genomic-SSR 和 EST-SSR 标记之间的 16 白杨克隆的基因差别。等位基因的平均数字由 genomic-SSR 检测了的统计结果表演是 4.1， Shannons 索引 1.0646，观察了杂合现象 0.4427 并且，为 EST-SSR 期望杂合现象 0.5523，等位基因的平均数字是 2.8， Shannons 索引 0.6985，观察了杂合现象 0.2330 并且期望杂合现象 0.4684。簇分析显示 genotypic 鉴定的 EST-SSR 能力比 genomic-SSR 的更精确。这些结果表明 EST-SSR 和 genomic-SSR 在多型性察觉和 genotypic 鉴定有统计上重要的基因差别。这些差别能在种类差异和另外的相关研究为 SSR 标记的合理使用提供一个理论基础。

Differences of EST-SSR and genomic-SSR markers in assessing genetic diversity in poplar

Out of the Himalaya-Hengduan Mountains: Phylogenomics and biogeography of the widely distributed Northern Hemisphere genus Polygonatum Mill. (Asparagaceae).

Background Although molecular analysis offers a wide range of options for species identification, a universal methodology for classifying and distinguishing closely related species remains elusive. This study validated the effectiveness of utilizing the entire chloroplast (cp) genome as a super-barcode to help identify and classify closely related species. Methods We here compared 26 complete cp genomes of ten Fritillaria species including 18 new sequences sequenced in this study. Each species had repeats and the cp genomes were used as a whole DNA barcode to test whether they can distinguish Fritillaria species. Results The cp genomes of Fritillaria medicinal plants were conserved in genome structure, gene type, and gene content. Comparison analysis of the Fritillaria cp genomes revealed that the intergenic spacer regions were highly divergent compared with other regions. By constructing the phylogenetic tree by the maximum likelihood and maximum parsimony methods, we found that the entire cp genome showed a high discrimination power for Fritillaria species with individuals of each species in a monophyletic clade. These results indicate that cp genome can be used to effectively differentiate medicinal plants from the genus Fritillaria at the species level. Conclusions This study implies that cp genome can provide distinguishing differences to help identify closely related Fritillaria species, and has the potential to be served as a universal super-barcode for plant identification.

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Plant super-barcode: a case study on genome-based identification for closely related species of Fritillaria.

The moonseed genus Menispermum L. (Menispermaceae) is disjunctly distributed in East Asia and eastern North America. Although Menispermum has important medicinal value, genetic and genomic information is scarce, with very few available molecular markers. In the current study, we used Illumina transcriptome sequencing and de novo assembly of the two Menispermum species to obtain in-depth genetic knowledge. From de novo assembly, 53,712 and 78,921 unigenes were generated for M. canadense and M. dauricum, with 37,527 (69.87%) and 55,211 (69.96%) showing significant similarities against the six functional databases, respectively. Moreover, 521 polymorphic EST-SSRs were identified. Of them, 23 polymorphic EST-SSR markers were selected to investigate the population genetic diversity within the genus. The newly developed EST-SSR markers also revealed high transferability among the three examined Menispermaceae species. Overall, we provide the very first transcriptomic analyses of this important medicinal genus. In addition, the novel microsatellite markers developed here will aid future studies on the population genetics and phylogeographic patterns of Menispermum at the intercontinental geographical scale.

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De novo Transcriptome Assembly, Gene Annotation and SSR Marker Development in the Moon Seed Genus Menispermum (Menispermaceae)

Comparative plastome genomics and phylogenetic analyses of Liliaceae

Introduction Phylogenomics have been widely used to resolve ambiguous and controversial evolutionary relationships among plant species and genera, and the identification of unique indels in plastomes may even help to understand the evolution of some plant families. Menispermum L. (Menispermaceae) consists of three species, M. dauricum DC., M. canadense L., and M. mexicanum Rose, which are disjuncly distributed among East Asia, Eastern North America and Mexico. Taxonomists continue to debate whether M. mexicanum is a distinct species, a variety of M. dauricum, or simply a synonym of M. canadense. To date, no molecular systematics studies have included this doubtful species in phylogenetic analyses. Methods In this study, we examined phylogenomics and phylogeography of Menispermum across its entire range using 29 whole plastomes of Menispermaceae and 18 ITS1&ITS2 sequences of Menispermeae. We reconstructed interspecific relationships of Menispermum and explored plastome evolution in Menispermaceae, revealing several genomic hotspot regions for the family. Results and discussion Phylogenetic and network analyses based on whole plastome and ITS1&ITS2 sequences show that Menispermum clusters into two clades with high support values, Clade A (M. dauricum) and Clade B (M. canadense + M. mexicanum). However, M. mexicanum is nested within M. canadense and, as a result, we support that M. mexicanum is a synonym of M. canadense. We also identified important molecular variations in the plastomes of Menispermaceae. Several indels and consequently premature terminations of genes occur in Menispermaceae. A total of 54 regions were identified as the most highly variable plastome regions, with nucleotide diversity (Pi) values > 0.05, including two coding genes (matK, ycf1), four introns (trnK intron, rpl16 intron, rps16 intron, ndhA intron), and 48 intergenic spacer (IGS) regions. Of these, four informative hotspot regions (trnH-psbA, ndhF-rpl32, trnK-rps16, and trnP-psaJ) should be especially useful for future studies of phylogeny, phylogeography and conservation genetics of Menispermaceae.

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Shen-Yi Wang

Papers

De novo Transcriptome Assembly, Gene Annotation and SSR Marker Development in the Moon Seed Genus Menispermum (Menispermaceae)

Comparative plastome genomics and phylogenetic analyses of Liliaceae

Phylogenomics and phylogeography of Menispermum (Menispermaceae)