[New records of medicinal plants in Tibet].

By the fourth survey of Chinese medicinal resources, new medicinal plants records of 2 genera and 5 species were reported in Tibet. They are two genera Rhynchoglossum and Asteropyrum, and five species including Rh. obliquum, A. peltatum, Urena repanda, Schefflera khasiana and Mimulus tenellus. All the voucher specimens are preserved in Herbarium of Tibet Agriculture and Animal Husbandry University.

Integrated Analysis of Transcriptomic and Proteomics Data Reveals the Induction Effects of Rotenoid Biosynthesis of Mirabilis himalaica Caused by UV-B Radiation.

Mirabilis himalaica (Edgew.) Heimerl is one of the most important genuine medicinal plants in Tibet, in which the special plateau habitat has been associated with its excellent medicinal quality and efficacy. However, the mechanisms by which environmental factors affect biosynthesis of secondary metabolic components remain unclear in this species. In this study, RNA sequencing and iTRAQ (isobaric Tags for Relative and Absolute Quantification) techniques were used to investigate the critical molecular "events" of rotenoid biosynthesis responding to UV-B radiation, a typical plateau ecological factor presented in native environment-grown M. himalaica plants. A total of 3641 differentially expressed genes (DEGs) and 106 differentially expressed proteins (DEPs) were identified in M. himalaica between UV-B treatment and control check (CK). Comprehensive analysis of protein and transcript data sets resulted in 14 and 7 DEGs from the plant hormone signal transduction and phosphatidylinositol signaling system pathways, respectively, being significantly enriched. The result showed that the plant hormone signal transduction and phosphatidylinositol signaling system might be the key metabolic strategy of UV-B radiation to improve the biosynthesis of rotenoid in M. himalaica. At same time, most of the DEGs were associated with auxin and calcium signaling, inferring that they might drive the downstream transmission of these signal transduction pathways. Regarding those pathways, two chalcone synthase enzymes, which play key roles in the biosynthesis of rotenoid that were thought as the representative medicinal component of M. himalaica, were significantly upregulated in UV-B radiation. This study provides a theoretical basis for further exploration of the adaptation mechanism of M. himalaica to UV-B radiation, and references for cultivation standardization.

Integrated analysis of transcriptomic and metabolomic data reveals critical metabolic pathways involved in rotenoid biosynthesis in the medicinal plant Mirabilis himalaica.

Mirabilis himalaica (Edgew.) Heimerl is among the most important genuine medicinal plants in Tibet. However, the biosynthesis mechanisms of the active compounds in this species are unclear, severely limiting its application. To clarify the molecular biosynthesis mechanism of the key representative active compounds, specifically rotenoid, which is of special medicinal value for M. himalaica, RNA sequencing and TOF-MS technologies were used to construct transcriptomic and metabolomic libraries from the roots, stems, and leaves of M. himalaica plants collected from their natural habitat. As a result, each of the transcriptomic libraries from the different tissues was sequenced, generating more than 10 Gb of clean data ultimately assembled into 147,142 unigenes. In the three tissues, metabolomic analysis identified 522 candidate compounds, of which 170 metabolites involved in 114 metabolic pathways were mapped to the KEGG. Of these genes, 61 encoding enzymes were identified to function at key steps of the pathways related to rotenoid biosynthesis, where 14 intermediate metabolites were also located. An integrated analysis of metabolic and transcriptomic data revealed that most of the intermediate metabolites and enzymes related to rotenoid biosynthesis were synthesized in the roots, stems and leaves of M. himalaica, which suggested that the use of non-medicinal tissues to extract compounds was feasible. In addition, the CHS and CHI genes were found to play important roles in rotenoid biosynthesis, especially, since CHS might be an important rate-limiting enzyme. This study provides a hypothetical basis for the screening of new active metabolites and the metabolic engineering of rotenoid in M. himalaica.

Molecular cloning and transgenic characterization of the genes encoding chalcone synthase and chalcone isomerase from the Tibetan herbal plant Mirabilis himalaica.

Mirabilis himalaica is an endangered medicinal plant species in the Tibetan Plateau. The two genes respectively encoding chalcone synthase (MhCHS) and chalcone isomerase (MhCHI) were isolated and characterized from M. himalaica. The sequence analysis revealed that the two genes were similar with their corresponding homologous genes in other plants. The tissue profiles showed that both MhCHS and MhCHI had higher expression levels in roots than in stems and leaves. Transgenic hairy root cultures respectively with overexpressing MhCHS and MhCHI were established. The genomic PCR detection confirmed the authority of transgenic hairy root lines, in which either MhCHS or MhCHI expression levels were much higher than that in non-transgenic hairy root line. Finally, the HPLC detection results demonstrated that the rotenoid contents in MhCHS/MhCHI-transformed hairy root lines were enhanced. This study provided two candidate genes that could be used to genetic engineering rotenoid biosynthesis in M. himalaica and an alternative method to produce rotenoid using transgenic hairy root cultures.

[Study on medicinal plant resources and diversity in Rhinopithecus bieti national natural reserve of Markam in Tibet].

This research was a part of the investigation of traditional Chinese medicine resources survey in Markam. The medicinal plants in natural reserve were studied for the first in this paper. There were 300 species in 202 genera of 54 families, among them there were 7 species of ferns in 5 genera of 5 families, 6 species of gymnosperms in 4 genera of 3 families, and 287 species of angiosperms in 194 genera of 61 families. There were 166 species Tibetan medicinal plants in 102 genera of 47 families. Quantitative analysis was carried out in 6 aspects of family and genus composition, medicinal parts, drug properties, flavour of a drug, Tibetan medicine, toxicity and new plants. The concrete suggestions of protection and exploitation were put forward, which provided scientific basis for the sustainable utilization of medicinal plants in this area.