Distinctive prokaryotic microbiomes in sympatric plant roots from a Yucatan cenote.

OBJECTIVE: Cenotes are flooded caves in Mexico's Yucatan peninsula. Many cenotes are interconnected in an underground network of pools and streams forming a vast belowground aquifer across most of the peninsula. Many plants in the peninsula grow roots that reach the cenotes water and live submerged in conditions similar to hydroponics. Our objective was to study the microbial community associated with these submerged roots of the Sac Actun cenote. We accomplished this objective by profiling the root prokaryotic community using 16S rRNA gene amplification and sequencing. RESULTS: We identified plant species by DNA barcoding the total genomic DNA of each root. We found a distinctive composition of the root and water bacterial and archaeal communities. Prokaryotic diversity was higher in all plant roots than in the surrounding freshwater, suggesting that plants in the cenotes may attract and select microorganisms from soil and freshwater, and may also harbor vertically transmitted lineages. The reported data are of interest for studies targeting biodiversity in general and root-microbial ecological interactions specifically.

Effects of Water Availability in the Soil on Tropane Alkaloid Production in Cultivated Datura stramonium.

BACKGROUND: different Solanaceae and Erythroxylaceae species produce tropane alkaloids. These alkaloids are the starting material in the production of different pharmaceuticals. The commercial demand for tropane alkaloids is covered by extracting them from cultivated plants. Datura stramonium is cultivated under greenhouse conditions as a source of tropane alkaloids. Here we investigate the effect of different levels of water availability in the soil on the production of tropane alkaloids by D. stramonium. METHODS: We tested four irrigation levels on the accumulation of tropane alkaloids. We analyzed the profile of tropane alkaloids using an untargeted liquid chromatography/mass spectrometry method. RESULTS: Using a combination of informatics and manual interpretation of mass spectra, we generated several structure hypotheses for signals in D. stramonium extracts that we assign as putative tropane alkaloids. Quantitation of mass spectrometry signals for our structure hypotheses across different anatomical organs allowed us to identify patterns of tropane alkaloids associated with different levels of irrigation. Furthermore, we identified anatomic partitioning of tropane alkaloid isomers with pharmaceutical applications. CONCLUSIONS: Our results show that soil water availability is an effective method for maximizing the production of specific tropane alkaloids for industrial applications.

Elucidating the Distribution of Plant Metabolites from Native Tissues with Laser Desorption Low-Temperature Plasma Mass Spectrometry Imaging.

Secondary metabolites of plants have important biological functions, which often depend on their localization in tissues. Ideally, a fresh untreated material should be directly analyzed to obtain a realistic view of the true sample chemistry. Therefore, there is a large interest for ambient mass-spectrometry-based imaging (MSI) methods. Our aim was to simplify this technology and to find an optimal combination of desorption/ionization principles for a fast ambient MSI of macroscopic plant samples. We coupled a 405 nm continuous wave (CW) ultraviolet (UV) diode laser to a three-dimensionally (3D) printed low-temperature plasma (LTP) probe. By moving the sample with a RepRap-based sampling stage, we could perform imaging of samples up to 16 × 16 cm2. We demonstrate the system performance by mapping mescaline in a San Pedro cactus ( Echinopsis pachanoi) cross section, tropane alkaloids in jimsonweed ( Datura stramonium) fruits and seeds, and nicotine in tobacco ( Nicotiana tabacum) seedlings. In all cases, the anatomical regions of enriched compound concentrations were correctly depicted. The modular design of the laser desorption (LD)-LTP MSI platform, which is mainly assembled from commercial and 3D-printed components, facilitates its adoption by other research groups. The use of the CW-UV laser for desorption enables fast imaging measurements. A complete tobacco seedling with an image size of 9.2 × 15.0 mm2 was analyzed at a pixel size of 100 × 100 µm2 (14 043 mass scans), in less than 2 h. Natural products can be measured directly from native tissues, which inspires a broad use of LD-LTP MSI in plant chemistry studies.

Abietane diterpenoids from the roots of some Mexican Salvia species (Labiatae): chemical diversity, phytogeographical significance, and cytotoxic activity.

From the roots of some Mexican Salvia species, classified in subgenus Jungia, several diterpenoids belonging to abietane (i.e., 3-7), salvifolane (9-->20,10-->6)-diabeoabietane) (i.e., 2), and totarane (i.e., 10) carbocyclic skeletons were isolated together with two 20-nor- and one 6,7-secoabietane derivatives, 1 and 9, and 8, respectively. While compounds 2-10 were previously known from different sources, compound 1 is a new 20-norabietane derivative, whose structure was deduced by spectroscopic means and confirmed by X-ray-diffraction analysis. The phytogeographical significance of the distribution of 20-norabietanic diterpenoids in the genus suggested an evolutionary link between the Chinese and New-World Salvias. Compounds 2 and 8 were tested for cell-growth inhibition activity against several human cancer cell lines and human normal lymphocytes, while 2 showed a moderate cytotoxic activity, 8 exhibited a moderate yet selective activity against leukemia cell line.