Effects of light conditions on growth and defense compound contents of Datura inoxia and D. stramonium

Corona discharge plasma stimulated production of atropine in callus of Datura inoxia by DNA hypomethylation and gene regulation: a novel technology for plant cell and tissue culture

Few investigations have tested the practical use of cold plasma as a novel technology to meet the requirements in the plant cell and tissue culture field. To fill the knowledge gap, we intend to respond to the question of whether plasma priming influenced DNA ultrastructure and the production of atropine (a tropane alkaloid) in Datura inoxia. Calluses were treated with the corona discharge plasma at time durations ranging from 0 to 300 s. Significant increases (about 60%) in biomass were observed in the plasma-primed calluses. The plasma priming of calluses enhanced the accumulation of atropine about 2-fold. The plasma treatments increased proline concentrations and soluble phenols. The drastic increases in the activity of the phenylalanine ammonia-lyase (PAL) enzyme resulted from the applied treatments. Likewise, the plasma treatment of 180 s upregulated the expression of the PAL gene by 8-fold. Also, the expression of the ornithine decarboxylase (ODC) and tropinone reductase I (TR I) genes were stimulated by 4.3-fold and 3.2-fold, respectively, in response to the plasma treatment. The putrescine N-methyltransferase gene displayed a similar trend to that of TR I and ODC genes following the plasma priming. Methylation sensitive amplification polymorphism method was employed to explore the plasma-associated epigenetic changes in DNA ultrastructure. The molecular assessment referred to DNA hypomethylation, validating an epigenetic response. This biological assessment study validates the hypothesis that plasma priming of callus is an efficient, cost-effective, and eco-friendly tool to enhance callogenesis efficiency, elicit metabolism, affect gene regulation, and modify chromatin ultrastructure in D. inoxia.

Alkaloids of the Genus Datura: Review of a Rich Resource for Natural Product Discovery

The genus Datura (Solanaceae) contains nine species of medicinal plants that have held both curative utility and cultural significance throughout history. This genus’ particular bioactivity results from the enormous diversity of alkaloids it contains, making it a valuable study organism for many disciplines. Although Datura contains mostly tropane alkaloids (such as hyoscyamine and scopolamine), indole, beta-carboline, and pyrrolidine alkaloids have also been identified. The tools available to explore specialized metabolism in plants have undergone remarkable advances over the past couple of decades and provide renewed opportunities for discoveries of new compounds and the genetic basis for their biosynthesis. This review provides a comprehensive overview of studies on the alkaloids of Datura that focuses on three questions: How do we find and identify alkaloids? Where do alkaloids come from? What factors affect their presence and abundance? We also address pitfalls and relevant questions applicable to natural products and metabolomics researchers. With both careful perspectives and new advances in instrumentation, the pace of alkaloid discovery—from not just Datura—has the potential to accelerate dramatically in the near future.

Developmental and chemical characteristics of Melittis melissophyllum L. in limited access of sunlight

Introduction: Bastard balm grows in forests, in central and southeastern part of Europe. The herb of this species is rich in phenolics, mainly flavonoids, phenolic acids and coumarins. The plant is used in traditional European medicine, in digestive problems and for aromatizing tobacco and alcohol products.

Objective: The purpose of this study was to determine the influence of shading on bastard balm development and the accumulation of phenolics in its herb, with special respect to coumarin as a quality marker of this raw material.

Methods: The plants were cultivated in full sunlight, in 30% and 50% shade provided by shading nets. The herb was harvested from plants in the third year of vegetation, at four subsequent developmental stages and then subjected to chemical evaluation. In the raw material, the total contents of flavonoids, phenolic acids and coumarins was determined. The content of coumarin was analyzed using HPLC-DAD.

Results: Plants grown in 30% shade produced the highest number of flowers and seeds. They produced the highest mass of herb at the beginning of the seed-setting stage. The plants grown in full sunlight revealed the highest content of flavonoids and phenolic acids, especially during flowering and at the beginning of the seed-setting stage. The mass of herb obtained by plants cultivated at deep (50%) shade was the lowest, however, the content of coumarin in these plants was the highest.

Conclusion: The influence of shade on bastard balm was expressed by the herb mass and coumarin content increment. The plants thrived best in 30% shade, both in terms of flowering abundance and the mass of herb, whereas those from 50% shade were the richest in coumarin.

Effect of Shading on Development, Yield and Quality of Bastard Balm Herb (Melittis melissophyllum L.)

The aim of the study was to assess the effects of Melittis melissophyllum shading on its development and accumulation of phenolics. Their content (verbascoside, apiin, luteolin-7-O-glucoside, coumarin, 3,4-dihydroxycoumarin, o-coumaric acid 2-O-glucoside as well as o-coumaric, p-coumaric, chlorogenic, caffeic, ferulic and cichoric acid) was determined in the herb using HPLC-DAD. The results showed that the content of abovementioned flavonoids and phenolic acids was highest in plants grown under full sunlight. On the other hand, a higher content of coumarin was observed in shaded plants, especially after the seed-setting stage. A similar tendency was noted for the amount of chlorophyll a and b. The content of hydrogen peroxide and malondialdehyde, the activity of polyphenol oxidase and catalase and the antioxidant capacity of plant extracts (measured using DPPH, ABTS and FRAP assays) were found to be the highest in the plants grown in full sunlight. However, the plants grown in moderate (30%) shade were found to thrive best.

Temporal Effects of Thinning on the Leaf C:N:P Stoichiometry of Regenerated Broadleaved Trees in Larch Plantations

The shift from natural mixed broadleaved forests to pure coniferous plantations results in soil degradation and the unsustainable development of plantations due to the simple stand structure and low species diversity. Thinning can practically sustain the forest structure and promote the regeneration and growth of broadleaved trees in these pure coniferous plantations. The growth of regenerated broadleaved trees is closely related to leaf ecological stoichiometry, which is strongly restricted by environmental factors such as light, soil moisture, and nutrients after thinning. However, the temporal effects of thinning on leaf C:N:P stoichiometry are still not well understood, which constrains our understanding of implementing thinning in coniferous plantations to promote the regeneration and growth of broadleaved species, and further forming the mixed larch-broadleaf forests. Here, we compared canopy openness (i.e., light availability) and the soil and leaf stoichiometry for regenerated broadleaved trees in larch (Larix keampferi) plantations in short-term (1–3 years), medium-term (4–9 years), and long-term (≥10 years) periods after thinning, taking natural mixed broadleaved forests as a control in Northeast China. The results showed that the temporal effects of thinning were not significant with respect to soil C concentrations, but significant with respect to soil C:P and N:P ratios. The regenerated broadleaved trees adjusted their leaf N concentrations and C:N ratios in response to the changed environmental conditions after thinning over time. The responses of soil and leaf stoichiometry to thinning and their significant correlation indicated a strong interaction between the soil and understory regeneration following thinning. Thus, thinning affects the soil and leaf stoichiometry of regenerated trees over time. These findings provide new insights into the conversion of pure coniferous plantations into mixed larch-broadleaf forests by controlling thinning intervals.