Search Results (8)

Uncaria rhynchophylla, a medicinal plant extensively used in traditional Chinese medicine, is an important plant source of terpenoid indole alkaloids (TIAs), but the mechanism of TIA biosynthesis at molecular level remains unclear. Geraniol synthase (GES) serves as a crucial enzyme in catalyzing the formation of geraniol from geranyl pyrophosphate (GPP) in various plants, but the functional characterization of the GES gene in U. rhynchophylla has not been investigated. In this study, a GES was identified and characterized through genome mining and bioinformatic analysis. Functional validation was performed via a protein catalysis experiment, transient expression in Nicotiana benthamiana, and methyl jasmonate (MeJA) induction experiments. The full-length UrGES gene was 1761 bp, encoding a protein product of 586 amino acids with an estimated 67.5 kDa molecular weight. Multiple sequence alignments and phylogenetic analysis placed UrGES within the terpene synthase g (TPS-g) subfamily, showing high similarity to known GESs from other plants. Enzymatic assays confirmed that recombinant UrGES catalyzed GPP conversion to a single product of geraniol. The transient expression of UrGES resulted in geraniol accumulation in N. benthamiana, further confirming its function in vivo. UrGES expression was observed in leaves, stems, and roots, where leaves had the highest transcript levels. Moreover, MeJA treatment significantly upregulated UrGES expression, which positively correlated with an increase in alkaloid content. This study functionally characterizes UrGES as a geraniol synthase in U. rhynchophylla, contributing to the current knowledge of the TIA biosynthetic pathway. These findings may offer insights for future metabolic engineering aiming to enhance TIA yields for pharmaceutical and industrial applications. Full article

Volatile organic compounds (VOCs) released by the receptive syconia of Ficus species play a vital role in attracting highly species-specific pollinating fig wasps. The components of VOCs vary considerably among Ficus species, but are generally dominated by a few common terpenoid compounds or specific proportions of several compounds. Terpene synthase (TPS) is the main source of specific and diverse terpenoids, but the evolution of the TPS gene family in Ficus and the potential functions of the TPS genes in species-specific pollination remain largely unelucidated. In this study, using transcriptomes of ostiole bracts of receptive male figs from 24 Ficus species collected from South China and Southeast Asia, we comprehensively scanned and investigated the composition and evolutionary characteristics of all TPS genes in all 24 species. We identified 248 TPS genes, including 33 orthologous genes and six singletons. Sequence and phylogenetic analysis showed that a majority of the 248 TPSs contained the DDXXD and DTE motifs, rather than the DXDD motif, and involved all subfamilies (TPS-a,b,c,e/f and g) known in other angiosperm genomes, suggesting a very diverse and complex composition of class I TPSs during the receptive phase. In addition, compared to TPS-a, which is generally the largest subfamily in some plants, the TPS-b subfamily contained the highest number of genes in Ficus species. Expression profile comparison showed that the distribution and expression levels of different TPSs among different Ficus species differed considerably, but a few TPS genes were common across most species. Positive selection analysis showed that the Ficus TPS genes were mainly under purifying selection, with only four genes having positive selection signals and two genes having positive selection sites, and two genes having relatively fast-evolving rates. The present study demonstrates the basic evolutionary characteristics of TPS genes in Ficus and reveals the roles of TPSs in shaping the diversity and specificity of the fig–fig wasp symbiotic relationship. Full article

Rose (Rosa chinensis) is one of the most famous ornamental plants worldwide, with a variety of colors and fragrances. Terpene synthases (TPSs) play critical roles in the biosynthesis of terpenes. In this work, we report a comprehensive study on the genome-wide identification and characterization of the TPS family in R. chinensis. We identified 49 TPS genes in the R. chinensis genome, and they were grouped into five subfamilies (TPS-a, TPS-b, TPS-c, TPS-g and TPS-e/f). Phylogenetics, gene structure and conserved motif analyses indicated that the RcTPS genes possessed relatively conserved gene structures and the RcTPS proteins contained relatively conserved motifs. Multiple putative cis-acting elements involved in the stress response were identified in the promoter region of RcTPS genes, suggesting that some could be regulated by stress. The expression profile of RcTPS genes showed that they were predominantly expressed in the petals of open flowers, pistils, leaves and roots. Under osmotic and heat stresses, the expression of most RcTPS genes was upregulated. These data provide a useful foundation for deciphering the functional roles of RcTPS genes during plant growth as well as addressing the link between terpene biosynthesis and abiotic stress responses in roses. Full article

Human ATP-binding cassette (ABC) subfamily G member 2 (ABCG2) mediates the transport of a wide variety of conventional cytotoxic anticancer drugs and molecular targeted agents. Consequently, the overexpression of ABCG2 in cancer cells is linked to the development of the multidrug resistance (MDR) phenotype. TP-3654 is an experimental second-generation inhibitor of PIM kinase that is currently under investigation in clinical trials to treat advanced solid tumors and myelofibrosis. In this study, we discovered that by attenuating the drug transport function of ABCG2, TP-3654 resensitizes ABCG2-overexpressing multidrug-resistant cancer cells to cytotoxic ABCG2 substrate drugs topotecan, SN-38 and mitoxantrone. Moreover, our results indicate that ABCG2 does not mediate resistance to TP-3654 and may not play a major role in the induction of resistance to TP-3654 in cancer patients. Taken together, our findings reveal that TP-3654 is a selective, potent modulator of ABCG2 drug efflux function that may offer an additional combination therapy option for the treatment of multidrug-resistant cancers. Full article

Terpenoids are the largest class of plant secondary metabolites and are one of the major emitted volatile compounds released to the atmosphere. They have functions of attracting pollinators or defense function, insecticidal properties, and are even used as pharmaceutical agents. Because of the importance of terpenoids, an increasing number of plants are required to investigate the function and evolution of terpene synthases (TPSs) that are the key enzymes in terpenoids biosynthesis. Orchidacea, containing more than 800 genera and 28,000 species, is one of the largest and most diverse families of flowering plants, and is widely distributed. Here, the diversification of the TPSs evolution in Orchidaceae is revealed. A characterization and phylogeny of TPSs from four different species with whole genome sequences is available. Phylogenetic analysis of orchid TPSs indicates these genes are divided into TPS-a, -b, -e/f, and g subfamilies, and their duplicated copies are increased in derived orchid species compared to that in the early divergence orchid, A. shenzhenica. The large increase of both TPS-a and TPS-b copies can probably be attributed to the pro-duction of different volatile compounds for attracting pollinators or generating chemical defenses in derived orchid lineages; while the duplications of TPS-g and TPS-e/f copies occurred in a species-dependent manner. Full article

Clematis florida is a popular ornamental vine species known for diverse colors and shapes of its flowers but not for scent. Here we investigated the composition and biosynthesis of floral scent in ‘Kaiser’, a fragrant cultivar of C. florida that has sterile flowers. Volatile profiling revealed that flowers of ‘Kaiser’ emit more than 20 compounds, with monoterpenes being most abundant. Among the three floral organs, namely sepals, transformed-petals, and ovaries, ovaries had the highest rates of total volatile emission. To determine the molecular mechanism underlying floral scent biosynthesis in ‘Kaiser’, we sequenced a flower transcriptome and searched the transcriptome for terpene synthase genes (TPSs), which are key genes for terpene biosynthesis. Among the TPS genes identified, three were putative intact full-length genes and were designated CfTPS1, CfTPS2, and CfTPS3. Phylogenetic analysis placed CfTPS1, CfTPS2, and CfTPS3 to the TPS-g, TPS-b, and TPS-a subfamily, respectively. Through in vitro enzyme assays with Escherichia coli-expressed recombinant proteins, both CfTPS1 and CfTPS2 were demonstrated to catalyze the conversion of geranyl diphosphate to linalool, the most abundant constituent of C. florida floral scent. In addition, CfTPS1 and CfTPS2 produced the sesquiterpene nerolidol from (E,E)-farnesyl diphosphate. CfTPS3 showed sesquiterpene synthase activity and produced multiple products in vitro. All three CfTPS genes showed higher levels of expression in sepals than those in transformed-petals and ovaries. Our results show that despite being sterile, the flowers of ‘Kaiser’ have normal mechanisms for floral scent biosynthesis that make the flowers fragrant. Full article

Schizothoracine is the predominant wild fish subfamily of the Tibetan plateau (TP). Their scales, pharyngeal teeth and barbels have gradually regressed with increasing altitude. Schizothoracine have been divided into three groups: primitive, specialized and highly specialized. Ectodysplasin-A (Eda) has been considered as a major gene that contributes to the development of skin appendages. The present study cloned the Eda genes of 51 Schizothoracine fish species which represent the three groups and five Barbinae species. Phylogenetic analyses indicated that Eda may have acted as the genetic trigger for scale loss in the Schizothoracine. Furthermore, 14 single nucleotide polymorphisms (SNPs) and two deletions (18 bp and 6 bp in size), were also detected in the Eda coding sequence of the highly specialized group compared to the primitive group. The same SNPs and two indels result in four non-synonymous and two G-X-Y and 1 XY motif indels, which possibly contribute to significant structure changes in the Eda gene. The domain including (G-X-Y)_n motif in the Eda gene is relatively conserved amongst teleosts. Based on the above results, we hypothesize that the evolution of Eda gene might be associated with the scale loss in Schizothoracine fishes in response to the phased uplift of the TP. Full article

Trehalose is a nonreducing α,α-1,1-disaccharide in a wide range of organisms, and has diverse biological functions that range from serving as an energy source to acting as a protective/signal sugar. However, significant amounts of trehalose have rarely been detected in higher plants, and the function of trehalose in the drought-tolerant crop cassava (Manihot esculenta Crantz) is unclear. We measured soluble sugar concentrations of nine plant species with differing levels of drought tolerance and 41 cassava varieties using high-performance liquid chromatography with evaporative light-scattering detector (HPLC-ELSD). Significantly high amounts of trehalose were identified in drought-tolerant crops cassava, Jatropha curcas, and castor bean (Ricinus communis). All cassava varieties tested contained high amounts of trehalose, although their concentrations varied from 0.23 to 1.29 mg·g⁻¹ fresh weight (FW), and the trehalose level was highly correlated with dehydration stress tolerance of detached leaves of the varieties. Moreover, the trehalose concentrations in cassava leaves increased 2.3–5.5 folds in response to osmotic stress simulated by 20% PEG 6000. Through database mining, 24 trehalose pathway genes, including 12 trehalose-6-phosphate synthases (TPS), 10 trehalose-6-phosphate phosphatases (TPP), and two trehalases were identified in cassava. Phylogenetic analysis indicated that there were four cassava TPS genes (MeTPS1–4) that were orthologous to the solely active TPS gene (AtTPS1 and OsTPS1) in Arabidopsis and rice, and a new TPP subfamily was identified in cassava, suggesting that the trehalose biosynthesis activities in cassava had potentially been enhanced in evolutionary history. RNA-seq analysis indicated that MeTPS1 was expressed at constitutionally high level before and after osmotic stress, while other trehalose pathway genes were either up-regulated or down-regulated, which may explain why cassava accumulated high level of trehalose under normal conditions. MeTPS1 was then transformed into tobacco (Nicotiana benthamiana). Results indicated that transgenic tobacco lines accumulated significant level of trehalose and possessed improved drought stress tolerance. In conclusion, cassava accumulated significantly high amount of trehalose under normal conditions due to multiplied trehalose biosynthesis gene families and constant expression of the active MeTPS1 gene. High levels of trehalose subsequently contributed to high drought stress tolerance. Full article