SMRT sequencing of a full-length transcriptome reveals transcript variants involved in C18 unsaturated fatty acid biosynthesis and metabolism pathways at chilling temperature in Pennisetum giganteum.

BACKGROUND: Pennisetum giganteum, an abundant, fast-growing perennial C4 grass that belongs to the genus Pennisetum, family Poaceae, has been developed as a source of biomass for mushroom cultivation and production, as a source of forage for cattle and sheep, and as a tool to remedy soil erosion. However, having a chilling-sensitive nature, P. giganteum seedlings need to be protected while overwintering in most temperate climate regions. RESULTS: To elucidate the cold stress responses of P. giganteum, we carried out comprehensive full-length transcriptomes from leaf and root tissues under room temperature (RT) and chilling temperature (CT) using PacBio Iso-Seq long reads. We identified 196,124 and 140,766 full-length consensus transcripts in the RT and CT samples, respectively. We then systematically performed functional annotation, transcription factor identification, long non-coding RNAs (lncRNAs) prediction, and simple sequence repeat (SSR) analysis of those full-length transcriptomes. Isoform analysis revealed that alternative splicing events may be induced by cold stress in P. giganteum, and transcript variants may be involved in C18 unsaturated fatty acid biosynthesis and metabolism pathways at chilling temperature in P. giganteum. Furthermore, the fatty acid composition determination and gene expression level analysis supported that C18 unsaturated fatty acid biosynthesis and metabolism pathways may play roles during cold stress in P. giganteum. CONCLUSIONS: We provide the first comprehensive full-length transcriptomic resource for the abundant and fast-growing perennial grass Pennisetum giganteum. Our results provide a useful transcriptomic resource for exploring the biological pathways involved in the cold stress responses of P. giganteum.

Coumarins from the Herb Cnidium monnieri and chemically modified derivatives as antifoulants against Balanus albicostatus and Bugula neritina larvae.

In the search for new environmental friendly antifouling (AF) agents, four coumarins were isolated from the herbal plant Cnidium monnieri, known as osthole (1), imperatorin (2), isopimpinellin (3) and auraptenol (4). Furthermore, five coumarin derivatives, namely 8-epoxypentylcoumarin (5), meranzin hydrate (6), 2'-deoxymetranzin hydrate (7), 8-methylbutenalcoumarin (8), and micromarin-F (9) were synthesized from osthole. Compounds 1, 2, 4, 7 showed high inhibitory activities against larval settlement of Balanus albicostatus with EC(50) values of 4.64, 3.39, 3.38, 4.67 µg mL-1. Compound 8 could significantly inhibit larval settlement of Bugula neritina with an EC(50) value of 3.87 µg mL-1. The impact of functional groups on anti-larval settlement activities suggested that the groups on C-5' and C-2'/C-3' of isoamylene chian could affect the AF activities.

Condensed tannins from Ulmus pumila L. leaves induce G2/M phase arrest and apoptosis via caspase-cascade activation in TFK-1 cholangiocarcinoma cells.

Condensed tannins the polyphenolic compounds that are widespread in plants have been proved to have antitumor potential. Here, we purified the bioactive condensed tannins from leaves of Ulmus pumila L. and explored their structural characteristics, antitumor effect on TFK-1 cholangiocarcinoma cells as well as the related potential mechanism. The UV-Vis, FT-IR spectroscopy, ESI-Full-MS, and thiolysis-HPLC-ESI-MS demonstrated that U. pumila condensed tannins (UCTs) consisted essentially of procyanidins with epicatechin as the main flavan-3-ol extension unit. The UCTs could significantly reduce the survival rate of human cholangiocarcinoma TFK-1, SK-CHA-1, and MZ-CHA-1 cells with the better inhibitory effect on TFK-1 cell proliferation. Flow cytometric assay showed that UCTs affected TFK-1 survival by G2/M phase arrest and inducing apoptosis in a dose-dependent manner. In addition, a total of 6592 differentially expressed genes (DEGs), consisting of 94 upregulated and 6498 downregulated DEGs, were identified between untreated and UCTs-treated TFK-1 cells using RNA-seq technology. Enrichment analysis based on the KEGG database revealed that these DEGs were closely associated with cell cycle and p53 apoptotic signaling pathways. Furthermore, qRT-PCR confirmed that treatment of UCTs to TFK-1 cells caused significant changes in the expression of cyclin E, cdc25 A, cytochrome c, caspase-3, and caspase-8. These results indicated that UCTs exhibited the growth inhibition effect on TFK-1 cells possibly via G2/M cell cycle arrest and activation of caspase-cascade to induce apoptosis, and had potential as an anti-cholangiocarcinoma drug for further development. PRACTICAL APPLICATIONS: Ulmus pumila L. as a valuable tree species has been widely used in fields of medicine and food. Condensed tannins, the polyphenolic compounds widespread in plants, have been proved to have antitumor potential and be safe to normal cells. In this study, the condensed tannins from leaves of U. pumila (UCTs) remarkably suppressed cholangiocarcinoma (CCA) cell viability possibly via G2/M cell cycle arrest and activation of caspase-cascade to induce apoptosis. The results provided evidence for the application of UCTs as a potential therapeutic drug for CCA tumor.

Characterization of terpenoids from the root of Ceriops tagal with antifouling activity.

One new dimeric diterpenoid, 8(14)-enyl-pimar-2'(3')-en-4'(18')-en-15'(16')-endolabr- 16,15,2',3'-oxoan-16-one (1) and five known terpenoids: Tagalsin C (2), Tagalsin I (3), lup-20(29)-ene-3ß,28-diol (4), 3-oxolup-20(29)-en-28-oic acid (5) and 28-hydroxylup- 20(29)-en-3-one (6) were isolated from the roots of the mangrove plant Ceriops tagal. Their structures and relative stereochemistry were elucidated by means of extensive NMR, IR and MS analysis. The antifouling activity against larval settlement of the barnacle Balanus albicostatus were evaluated using capsaicin as a positive control. All these terpenoids exhibited antifouling activity against cyprid larvae of the barnacle without significant toxicity. The structure-activity relationship results demonstrated that the order of antifouling activity was diterpenoid (Compound 2) > triterpenoid (Compounds 4, 5 and 6) > dimeric diterpenoid (Compounds 1 and 3). The functional groups on the C-28 position of lupane triterpenoid significantly affect the antifouling activity. The diterpenoid dimmer with two identical diterpenoid subunits might display more potent antifouling activity than one with two different diterpenoid subunits. The stability test showed that Compounds 2, 4, 5 and 6 remained stable over 2-month exposure under filtered seawater.

RNA-seq based transcriptomic analysis uncovers α-linolenic acid and jasmonic acid biosynthesis pathways respond to cold acclimation in Camellia japonica.

Camellia is a well-known ornamental flower native to Southeast of Asia, including regions such as Japan, Korea and South China. However, most species in the genus Camellia are cold sensitive. To elucidate the cold stress responses in camellia plants, we carried out deep transcriptome sequencing of 'Jiangxue', a cold-tolerant cultivar of Camellia japonica, and approximately 1,006 million clean reads were generated using Illumina sequencing technology. The assembly of the clean reads produced 367,620 transcripts, including 207,592 unigenes. Overall, 28,038 differentially expressed genes were identified during cold acclimation. Detailed elucidation of responses of transcription factors, protein kinases and plant hormone signalling-related genes described the interplay of signal that allowed the plant to fine-tune cold stress responses. On the basis of global gene regulation of unsaturated fatty acid biosynthesis- and jasmonic acid biosynthesis-related genes, unsaturated fatty acid biosynthesis and jasmonic acid biosynthesis pathways were deduced to be involved in the low temperature responses in C. japonica. These results were supported by the determination of the fatty acid composition and jasmonic acid content. Our results provide insights into the genetic and molecular basis of the responses to cold acclimation in camellia plants.