Metabolic Characterization of Hyoscyamus niger Ornithine Decarboxylase

Ornithine decarboxylase (ODC) catalyzes ornithine decarboxylation to yield putrescine, a key precursor of polyamines, and tropane alkaloids (TAs). Here, to investigate in depth the role of ODC in polyamine/TA biosynthesis and to provide a candidate gene for engineering polyamine/TA production, the ODC gene (HnODC) was characterized from Hyoscyamus niger, a TA-producing plant. Our phylogenetic analysis revealed that HnODC was clustered with ODC enzymes of plants. Experimental work showed HnODC highly expressed in H. niger roots and induced by methyl jasmonate (MeJA). In the MeJA treatment, the production of both putrescine and N-methylputrescine were markedly promoted in roots, while contents of putrescine, spermidine, and spermine were all significantly increased in leaves. By contrast, MeJA did not significantly change the production of either hyoscyamine or scopolamine in H. niger plants. Building on these results, the 50-kDa His-tagged HnODC proteins were purified for enzymatic assays. When ornithine was fed to HnODC, the putrescine product was detected by HPLC, indicating HnODC catalyzed ornithine to form putrescine. Finally, we also investigated the enzymatic kinetics of HnODC. Its Km, Vmax, and Kcat values for ornithine were respectively 2.62 ± 0.11 mM, 1.87 ± 0.023 nmol min-1 μg-1 and 1.57 ± 0.015 s-1, at pH 8.0 and at 30°C. The HnODC enzyme displays a much higher catalytic efficiency than most reported plant ODCs, suggesting it may be an ideal candidate gene for engineering polyamine/TA biosynthesis

The complete mitochondrial genome sequence of Mirabilis himalaica, an endemic plant to Tibet

The complete mitochondrial genome of the important medicinal plant Mirabilis himalaica has been reported in this study. It was 346,363 bp in size with a GC content of 44.6% and contained 42 protein-coding genes (30 known functional genes, 11 ORF genes and one ycf2 gene of unknown function), 27 tRNA genes, and four rRNA genes. Most of the genes were single-copy genes, only three were duplicated and two were multi-copy. Phylogenetic analysis showed M. himalaica to be closely clustered with Silene latifolia, Spinacia oleracea and Beta vulgaris, all species belong to the order Caryophyllales

The complete chloroplast genome sequence of Rumex nepalensis Spreng

Rumex nepalensis is a traditional Chinese herb used for detoxification, hemostasis, and anti-inflammatory. In this study, the complete chloroplast sequence of R. nepalensis was characterized from Illumina pair-end sequencing. The cpDNA was 159,044 bp in length, containing a pair of inverted repeats of 30,623 bp each separated by a large and small single copy region of 84,819 bp and 12,979 bp, respectively. The complete chloroplast genome of R. nepalensis contained 128 genes, 37 tRNA, and 8 rRNA. Phylogenetic tree demonstrated that R. nepalensis was closely related to Rumex acetosa

Achene mucilage formation process and extrusion from hydrated pericarp of Mirabilis himalaica

Myxospermy is an important feature of achenes of the alpine plant Mirabilis himalaica, and the achene mucilage increases the germination rate and early seedling growth during exposure to abiotic stresses, which has important functions that allow M. himalaica to survive the extreme climate of the Tibet Plateau. However, achene formation and mucilage extrusion are poorly understood. In the present study, comprehensive analyses were performed on mucilage production during achene development and mucilage release from hydrated achene pericarp in M. himalaica. First, fertilization initiated the development of M. himalaica achenes, during which their color, size and texture were altered dramatically. Second, using a metachromatic staining procedure, cytological events, the establishment of mucilage secretory cells in the inner epicarp layer were observed. The hydration of mature achenes led to the rapid bursting of mucilage secretory cells, which released a hydrophilic gel that surrounded the achenes. Finally, enzymatic digestion indicated that major components of the mucilage were pectins; glucose (41.40%), rhamnose (26.58%), galactose (18.33%), trehalose (12.12%), and mannose (1.57%) were found to be the components of achene by using ion-exchange chromatography

Characterization of the complete chloroplast genome sequence of the medicinal plant Mirabilis himalaica

Mirabilis himalaica is an old and popular medicinal plant used in traditional Tibetan folk medicine. Here, we reported the complete chloroplast genome sequence of Mirabilis himalaica. The assembled chloroplast genome was 154,348 bp long, containing a large single-copy region of 85,809 bp, a small single-copy region of 17,935 bp, and a pair of inverted repeat regions of 25,302 bp. It had 36% GC content and encoded 131 genes including 86 protein-coding genes, eight rRNA genes, and 37 tRNA. Fifteen and two genes contained one and two introns, respectively. Phylogenetic analysis revealed that Mirabilis himalaica was sister to Nyctaginia capitata

The complete chloroplast genome sequence of Polygonum chinense L.

Polygonum chinense is a traditional natural plant pharmaceutical with antimicrobial, antioxidant, and antidiarrheal effects and mainly distributed in China and Southeast Asian countries. The complete chloroplast sequence of P. chinense has been determined in this study. The cpDNA was 158,981 bp in length, containing a pair of inverted repeats of 30,872 bp each separated by a large and small single-copy region of 84,347 and 12,890 bp, respectively. The genome contained 86 protein-coding genes, eight rRNA genes, and 37 tRNA genes. The overall GC content of the chloroplast genome was 38%. Phylogenetic tree demonstrated that P. chinense closely related to Rheum palmatum and Rheum wittrockii

Incarvillea uniflora H. P. Deng & Chang Y. Xia 2021, sp. nov.

<i>Incarvillea uniflora</i> H.P. Deng & Chang Y. Xia, <i>sp. nov.</i> Figs.1, 2, 3 <p> Type:— China. Xizang: Markam County, Zongxi villages, 29° 48’ 02.74”N, 98° 42’ 43.88” E, grassland, Elev. 4061 m, 12 Dec. 2013, <i>X. Z</i> <i>. Lan, L. Q. Li & J.</i> <i>Luo 542129130803144 LY</i> (holotype: ISBC!).</p> <p> <b>Diagnosis</b>:— <i>Incarvillea uniflora</i> is most similar to <i>I. himalayensis</i>, but differs by leaves all simple (vs. usually pinnately lobed or reduce to single lobe), calyx lobes long triangular (vs. ovate to lanceolate), peduncles 6.5-16.5 cm (vs. 2.2–2.8(–4.5) cm), flowers solitary or clustered (vs. solitary or few in terminal racemes).</p> <p> <b>Description</b>:—Herbs perennial, 3–6(–50) cm tall, glabrescent. Leaves usually basal, rosette, simple, undivided; petiole 1–4.5(–9) cm; blade papery, ovate-elliptic to suborbicular, 4–8(–15) × 3–6(–10) cm, base and apex subrounded, margin subentire or shallowly serrate; lateral veins 7–9 on each side of midrib. Flowers solitary or 3–7 flowers in clusters. Pedicel ca. 6.5–16.5 cm. Bracts borne at the base of pedicel, lanceolate or broadly lanceolate, 5–9 × 1–2 mm, glabrous. Calyx campanulate, 2–3.5 cm; teeth long triangular, 0.4–1 cm × 1.5–5 mm, apex acute. Corolla red, 4.5–7 × ca. 4 cm; tube 4.5–5 cm, purple-red striate and spotted in the inner surface; lobes suborbicular, 1.5–1.9 × 2–2.5 cm. Stamens 4, dydinamous, inserted at base of corolla tube; filaments glandular-hairy 4; the longer pair 2 mm, the shorter pair 1.8 mm. Style 5–6 cm, stigma flabellate. Capsule lanceolate, compressed, 4-angled, 5–7 cm × 7–9 mm, apex acuminate. Seeds subspherical, 3.5–4.5 × 3–4 mm, wing 0.5–0.8 mm wide.</p> <p> <b>Etymology</b>:—The specific epithet ‘ <i>uniflora</i> ’ refers to the growth pattern of flowers, solitary or clustered.</p> <p> <b>Distribution, Habitat, and Phenology</b>:— <i>Incarvillea uniflora</i> is distributed in Hengduan Mountains (Markam County, Xizang, China). It grows in natural grassland at an elevation of 4061 m. The flowering period is from May to July and the fruiting period is from July to September.</p> <p> <b>Preliminary conservation status</b>:—The observation of the field population indicated that <i>Incarvillea uniflora</i> had a narrow distribution range, but its habitat, natural grassland, was very common in Hengduan Mountains. Furthermore, considering the <i>Incarvillea</i> species were widely distributed in Hengduan Mountain, we speculated that there could exist potential undiscovered populations. Therefore, it should be classified as Data Deficient (DD) based on the International Union for Conservation of Nature Red List criteria (IUCN 2012).</p> <p> <b>Additional specimens examined (Paratypes)</b>:— CHINA. Xizang: Markam, Nov. 2014, <i>X. Z</i> <i>. Lan, L. Q. Li & J.</i></p> <p> <i>Luo 542129140618419LY</i> (IBSC, SWCTU).</p> <p> <b>Additional specimens of related species examined</b>:— <i>I. forrestii</i>: CHINA. Yunnan, Singri-La, Jul. 1914, <i>G</i> <i>.</i> <i>Forrest 12676</i> (E); Singri-La, Jul. 1922, <i>G</i> <i>.</i> <i>Forrest 21526</i> (E); Sichuan, Muli,, <i>G</i> <i>.</i> <i>Forrest 30633</i> (E); CHINA. Sichuan: Ningnan, May 1978, <i>Ningnan team 0093</i> (SM). <i>I. mairei</i>: CHINA. Yunnan, Sep. 1929, <i>R</i> <i>. C.</i> <i>Qin 24368</i> (PE, KUN). <i>I. altissim</i>: CHINA. Sichuan: Xinlong, June 1974, <i>J</i> <i>. F.</i> <i>Wang 06393</i> (CDBI). <i>I. himalayensis</i>: BHUTAN. Chojo Dzong, July 1949, <i>F</i> <i>. Ludlow, G. Sherriff & J. H.</i> <i>Hicks 16722</i> (E).</p>Published as part of <i>Xia, Changying, Lan, Xiaozhong, Zuo, Youwei, Lin, Le & Deng, Hongping, 2021, Incarvillea uniflora (Bignoniaceae), a new species from Hengduan Mountains, southwest China, pp. 52-58 in Phytotaxa 528 (1)</i> on pages 54-57, DOI: 10.11646/phytotaxa.528.1.5, <a href="http://zenodo.org/record/5769254">http://zenodo.org/record/5769254</a&gt

Enhancing Tropane Alkaloid Production Based on the Functional Identification of Tropine-Forming Reductase in Scopolia lurida, a Tibetan Medicinal Plant

Scopolia lurida, a native herbal plant species in Tibet, is one of the most effective producers of tropane alkaloids. However, the tropane alkaloid biosynthesis in this plant species of interest has yet to be studied at the molecular, biochemical, and biotechnological level. Here, we report on the isolation and characterization of a putative short chain dehydrogenase (SDR) gene. Sequence analysis showed that SlTRI belonged to the SDR family. Phylogenetic analysis revealed that SlTRI was clustered with the tropine-forming reductases. SlTRI and the other TA-biosynthesis genes, including putrescine N-methyltransferase (SlPMT) and hyoscyamine 6β-hydroxylase (SlH6H), were preferably or exclusively expressed in the S. lurida roots. The tissue profile of SlTRI suggested that this gene might be involved in tropane alkaloid biosynthesis. By using GC-MS, SlTRI was shown to catalyze the tropinone reduction to yield tropine, the key intermediate of tropane alkaloids. With the purified recombinant SlTRI from Escherichiacoli, an enzymatic assay was carried out; its result indicated that SlTRI was a tropine-forming reductase. Finally, the role of SlTRI in promoting the tropane alkaloid biosynthesis was confirmed through metabolic engineering in S. lurida. Specifically, hairy root cultures of S. lurida were established to investigate the effects of SlTRI overexpression on tropane alkaloid accumulation. In the SlTRI-overexpressing root cultures, the hyoscyamine contents were 1.7- to 2.9-fold higher than those in control while their corresponding scopolamine contents were likewise elevated. In summary, this functional identification of SlTRI has provided for a better understanding of tropane alkaloid biosynthesis. It also provides a candidate gene for enhancing tropane alkaloid biosynthesis in S. lurida via metabolic engineering

The complete chloroplast genome sequence of Rhodiola kirilowii (Crassulaceae), a precious Tibetan drug in China

Rhodiola kirilowii is a precious Tibetan drug and an extremely endangered plant. In recent years, the number of individuals of R. kirilowii has decreased sharply. Here, we determined and analyzed the complete chloroplast genome of R. kirilowii. The cpDNA was 150,905 bp in length, containing a pair of inverted repeats (IRs) of 25,864 bp each separated by a large and small single copy (LSC and SSC) regions of 82,131 bp and 17,046 bp, respectively. The genome contained 84 protein-coding genes, 8 rRNA genes, and 36 tRNA genes. The overall GC content of the chloroplast genome was 37.8%, whereas the corresponding values of the LSC, SSC, and IR regions were 35.8, 31.7 and 42.9%, respectively. A maximum likelihood (ML) phylogenetic analysis demonstrated that Rhodiola sacra and Rhodiola crenulata were clustered into one clade with strong support values, indicating their closer relationship

A Novel UDP-Glycosyltransferase of Rhodiola crenulata Converts Tyrosol to Specifically Produce Icariside D2

Rhodiola crenulata is a Tibetan native herbal plant belonging to the family of Crassulaceae, which produces the pharmaceutical icariside D2 with the activities of inhibiting angiotensin-converting enzyme and killing leukemia cancer cells. In this study, we functionally characterized a novel UDP-glycosyltransferase (RcUGT1) that converted tyrosol to specifically produce icariside D2 from R. crenulata at molecular and biochemical levels. RcUGT1 was highly expressed in flowers and roots, while the icariside D2 content was much higher in stems than that in other organs, suggesting the potential translocation of icariside D2 from flowers and roots to stems. The high production of icariside D2 in stems provided a reasonable suggestion to farmers to harvest stems instead of roots for icariside D2 production. Enzymatic assays of recombinant RcUGT1 indicated that it converted tyrosol to specifically form icariside D2, with the values of Km 0.97±0.10 mM, Vmax 286±8.26 pKat/mg, Kcat 0.01552 s−1, and Kcat/Km 159.55 s−1 M−1. Functional identification of RcUGT1 facilitated the icariside D2 production through metabolic engineering in plants or synthetic biology in microbes