Metabolite profiling of the carnivorous pitcher plants Darlingtonia and Sarracenia

Sarraceniaceae is a New World carnivorous plant family comprising three genera: Darlingtonia, Heliamphora, and Sarracenia. The plants occur in nutrient-poor environments and have developed insectivorous capability in order to supplement their nutrient uptake. Sarracenia flava contains the alkaloid coniine, otherwise only found in Conium maculatum, in which its biosynthesis has been studied, and several Aloe species. Its ecological role and biosynthetic origin in S. flava is speculative. The aim of the current research was to investigate the occurrence of coniine in Sarracenia and Darlingtonia and to identify common constituents of both genera, unique compounds for individual variants and floral scent chemicals. In this comprehensive metabolic profiling study, we looked for compound patterns that are associated with the taxonomy of Sarracenia species. In total, 57 different Sarracenia and D. californica accessions were used for metabolite content screening by gas chromatography-mass spectrometry. The resulting high-dimensional data were studied using a data mining approach. The two genera are characterized by a large number of metabolites and huge chemical diversity between different species. By applying feature selection for clustering and by integrating new biochemical data with existing phylogenetic data, we were able to demonstrate that the chemical composition of the species can be explained by their known classification. Although transcriptome analysis did not reveal a candidate gene for coniine biosynthesis, the use of a sensitive selected ion monitoring method enabled the detection of coniine in eight Sarracenia species, showing that it is more widespread in this genus than previously believed.Peer reviewe

De novo transcriptome assembly of Conium maculatum L. to identify candidate genes for coniine biosynthesis

Poison hemlock (Conium maculatum L.) is a notorious weed containing the potent alkaloid coniine. Only some of the enzymes in the coniine biosynthesis have so far been characterized. Here, we utilize the next-generation RNA sequencing approach to report the first-ever transcriptome sequencing of five organs of poison hemlock: developing fruit, flower, root, leaf, and stem. Using a de novo assembly approach, we derived a transcriptome assembly containing 123,240 transcripts. The assembly is deemed high quality, representing over 88% of the near-universal ortholog genes of the Eudicots clade. Nearly 80% of the transcripts were functionally annotated using a combination of three approaches. The current study focuses on describing the coniine pathway by identifying in silico transcript candidates for polyketide reductase, l-alanine:5-keto-octanal aminotransferase, gamma-coniceine reductase, and S-adenosyl-l-methionine:coniine methyltransferase. In vitro testing will be needed to confirm the assigned functions of the selected candidates.Peer reviewe

Euglena gracilis growth and cell composition under different temperature, light and trophic conditions

BackgroundEuglena gracilis, a photosynthetic protist, produces protein, unsaturated fatty acids, wax esters, and a unique β-1,3-glucan called paramylon, along with other valuable compounds. The cell composition of E. gracilis was investigated in this study to understand how light and organic carbon (photo-, mixo- and heterotrophic conditions) affected growth and cell composition (especially lipids). Comparisons were primarily carried out in cultures grown at 23 °C, but the effect of growth at higher temperatures (27 or 30 °C) was also considered.Cell growthSpecific growth rates were slightly lower when E. gracilis was grown on glucose in either heterotrophic or mixotrophic conditions than when grown photoautotrophically, although the duration of exponential growth was longer. Temperature determined the rate of exponential growth in all cultures, but not the linear growth rate during light-limited growth in phototrophic conditions. Temperature had less effect on cell composition.Cell compositionAlthough E. gracilis was not expected to store large amounts of paramylon when grown phototrophically, we observed that phototrophic cells could contain up to 50% paramylon. These cells contained up to 33% protein and less than 20% lipophilic compounds, as expected. The biomass contained about 8% fatty acids (measured as fatty acid methyl esters), most of which were unsaturated. The fatty acid content of cells grown in mixotrophic conditions was similar to that observed in phototrophic cells, but was lower in cells grown heterotrophically. Heterotrophic cells contained less unsaturated fatty acids than phototrophic or mixotrophic cells. α-Linolenic acid was present at 5 to 18 mg g-1 dry biomass in cells grown in the presence of light, but at [less than] 0.5 mg g-1 biomass in cells grown in the dark. Eicosapentaenoic and docosahexaenoic acids were detected at 1 to 5 mg g-1 biomass. Light was also important for the production of vitamin E and phytol

Proof of Concept for Cell Culture-Based Coffee

The global coffee production is facing serious challenges including land use, climate change, and sustainability while demand is rising. Cellular agriculture is a promising alternative to produce plant-based commodities such as coffee, which are conventionally produced by farming. In this study, the complex process of drying and roasting was adapted for bioreactor-grown coffee cells to generate a coffee-like aroma and flavor. The brews resulting from different roasting regimes were characterized with chemical and sensory evaluation-based approaches and compared to conventional coffee. Roasting clearly influenced the aroma profile. In contrast to conventional coffee, the dominant odor and flavor attributes were burned sugar-like and smoky but less roasted. The intensities of bitterness and sourness were similar to those of conventional coffee. The present results demonstrate a proof of concept for a cellular agriculture approach as an alternative coffee production platform and guide future optimization work

Raspberry Ketone Accumulation in Nicotiana benthamiana and Saccharomyces cerevisiae by Expression of Fused Pathway Genes

Raspberry ketone has generated interest in recent years both as a flavor agent and as a health promoting supplement. Raspberry ketone can be synthesized chemically, but the value of a natural nonsynthetic product is among the most valuable flavor compounds on the market. Coumaroyl-coenzyme A (CoA) is the direct precursor for raspberry ketone but also an essential precursor for flavonoid and lignin biosynthesis in plants and therefore highly regulated. The synthetic fusion of 4-coumaric acid ligase (4CL) and benzalacetone synthase (BAS) enables the channeling of coumaroyl-CoA from the ligase to the synthase, proving to be a powerful tool in the production of raspberry ketone in both N. benthamiana and S. cerevisiae. To the best of our knowledge, the key pathway genes for raspberry ketone formation are transiently expressed in N. benthamiana for the first time in this study, producing over 30 μg/g of the compound. Our raspberry ketone producing yeast strains yielded up to 60 mg/L, which is the highest ever reported in yeast

Contrasting Dihydronaphthoquinone Patterns in Closely Related Drosera (Sundew) Species Enable Taxonomic Distinction and Identification

Dihydronaphthoquinones are described as constituents of sundews (Drosera), Venus flytraps (Dionaea), and dewy pines (Drosophyllum) for the first time. As in the corresponding naphthoquinones, these reduced derivatives may occur in two regio-isomeric series distinguished by the relative position of a methyl group (at position 2 or 7 in the naphthalene skeleton), depending on the taxon. Species producing plumbagin (2-methyljuglone, 1) do commonly contain the corresponding dihydroplumbagin (5), while species containing ramentaceone (7-methyljuglone, 2) also contain dihydroramentaceone (7-methyl-β-dihydrojuglone, 6). So far, only few species containing plumbagin (1) and dihydroplumbagin (5) additionally form dihydroramentaceone (6) but not ramentaceone (2). Thus, subtle but constant differences in the chemism of closely related and morphologically similar species reliably define and distinguish taxa within D. sect. Arachnopus, which is taken to exemplify their chemotaxonomic utility. The joint presence of quinones and hydroquinones allows observations and predictions on the chemical structures and the reactions of these intriguing natural products