A Systematic Review of Melatonin in Plants: An Example of Evolution of Literature

Melatonin (N-acetyl-5-methoxy-tryptamine) is a mammalian neurohormone, antioxidant and signaling molecule that was first discovered in plants in 1995. The first studies investigated plant melatonin from a human perspective quantifying melatonin in foods and medicinal plants and questioning whether its presence could explain the activity of some plants as medicines. Starting with these first handful of studies in the late 1990s, plant melatonin research has blossomed into a vibrant and active area of investigation and melatonin has been found to play critical roles in mediating plant responses and development at every stage of the plant life cycle from pollen and embryo development through seed germination, vegetative growth and stress response. Here we have utilized a systematic approach in accordance with the preferred reporting items for systematic reviews and meta-analyses (PRISMA) protocols to reduce bias in our assessment of the literature and provide an overview of the current state of melatonin research in plants, covering 1995–2021. This review provides an overview of the biosynthesis and metabolism of melatonin as well as identifying key themes including: abiotic stress responses, root development, light responses, interkingdom communication, phytohormone and plant signaling. Additionally, potential biases in the literature are investigated and a birefringence in the literature between researchers from plant and medical based which has helped to shape the current state of melatonin research. Several exciting new opportunities for future areas of melatonin research are also identified including investigation of non-crop and non-medicinal species as well as characterization of melatonin signaling networks in plants

Preliminary assessment of the conservation status of medicinal plant species in Canada

Natural health products in North America are a 9.6 billion US dollar industry that has seen increased demands particularly in products for immune support and anti-viral supplements in response to the Covid-19 pandemic. It has been estimated that ≈40% of the plant raw materials used in natural health products are wild-harvested each year but exact data is missing for many species. Our data show that there are at least 1445 medicinal plant species harvested for commercial products in Canada and 1217 of these are native species. Medicinal plants and non-timber forest crops are also increasingly impacted by climate change as suitable growing areas migrate. In order to ensure long term species survival in the wild, it is necessary to generate accurate information about distribution of wild populations, need for conservation and sustainable method development. Our objective was to provide a preliminary assessment on the conservation status of Canadian medicinal plants by analysis of the available data resources.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Daily consumption of a synbiotic yogurt decreases energy intake but does not improve gastrointestinal transit time: a double-blind, randomized, crossover study in healthy adults

Abstract Objective Probiotic and synbiotic products are widely marketed to healthy individuals, although potential benefits for these individuals are rarely studied. This study investigated the effect of daily consumption of a synbiotic yogurt on gastrointestinal (GI) function in a sample of healthy adults. Subjects/Methods In a randomized crossover double-blind study, 65 healthy adults consumed 200 g/day of yogurt with (synbiotic) or without (control) added probiotics (Bifidobacterium lactis Bb12, Lactobacillus acidophilus La5, Lactobacillus casei CRL431) and 4 g inulin for two 15-day treatment periods, each preceded by a 6-week washout period. GI transit time (GTT), duration of colour (DOC), GI symptoms and dietary intake were assessed and analyzed using repeated measures ANOVA, including PRE-treatment GTT as a covariate. Participants were grouped as short GTT (STT, n = 50, ≤32.7 h) or long GTT (LTT, n = 15, >32.7 h) based on their PRE-treatment GTT assessment. Results POST-treatment GTT and DOC were not different between synbiotic and control, and did not change from PRE-treatment, within the STT or LTT groups. There were no changes in GI symptom ratings, indicating that both yogurts were well tolerated. In STT, energy, fat and protein intakes were decreased from baseline with synbiotic (p = 0.055, p = 0.059 and p = 0.005, respectively) and dietary fibre intake was higher POST-treatment with synbiotic versus control (p = 0.0002). In LTT, decreases in energy and fat intakes with synbiotic were not significant (p = 0.14 and p = 0.18, respectively) and there were no differences in dietary fibre intake. Conclusion Consuming 200 g/day of synbiotic yogurt did not significantly alter GTT in healthy adults, but was well tolerated and helped to reduce overall energy intake

The Morphoregulatory Role of Thidiazuron: Metabolomics-Guided Hypothesis Generation for Mechanisms of Activity

Thidiazuron (TDZ) is a diphenylurea synthetic herbicide and plant growth regulator used to defoliate cotton crops and to induce regeneration of recalcitrant species in plant tissue culture. In vitro cultures of African violet thin petiole sections are an ideal model system for studies of TDZ-induced morphogenesis. TDZ induces de novo shoot organogenesis at low concentrations and somatic embryogenesis at higher concentrations of exposure. We used an untargeted metabolomics approach to identify metabolites in control and TDZ-treated tissues. Statistical analysis including metabolite clustering, pattern and pathway tools, logical algorithms, synthetic biotransformations and hormonomics identified TDZ-induced changes in metabolism. A total of 18,602 putative metabolites with extracted masses and predicted formulae were identified with 1412 features that were found only in TDZ-treated tissues and 312 that increased in response to TDZ. The monomer of TDZ was not detected intact in the tissues but putative oligomers were found in the database and we hypothesize that these may form by a Diels–Alder reaction. Accumulation oligomers in the tissue may act as a reservoir, slowly releasing the active TDZ monomer over time. Cleavage of the amide bridge released TDZ-metabolites into the tissues including organic nitrogen and sulfur containing compounds. Metabolomics data analysis generated six novel hypotheses that can be summarized as an overall increase in uptake of sugars from the culture media, increase in primary metabolism, redirection of terpene metabolism and mediation of stress metabolism via indoleamine and phenylpropanoid metabolism. Further research into the specific mechanisms hypothesized is likely to unravel the mode of action of TDZ and to provide new insights into the control of plant morphogenesis.Science, Faculty ofNon UBCChemistry, Department ofReviewedFacult

Selection and Micropropagation of an Elite Melatonin Rich Tulsi (Ocimum sanctum L.) Germplasm Line

Tulsi (Ocimum sanctum L.) is a sacred plant of medicinal and spiritual significance in many cultures. Medicinal properties of Tulsi are ascribed to its phytochemicals with antioxidant capabilities. The current study was undertaken to screen a large seed population of Tulsi to select germplasm lines with high antioxidant potential and to standardize protocols for micropropagation and biomass production to produce a phytochemically consistent crop. A total of 80 germplasm lines were established under in vitro conditions and screened for their antioxidant potential determined with the 2,2-diphenyl-1-picrylhydrazyl (DPPH) bioassay. The micropropagation of a selected line, named Vrinda, was established using nodal cultures grown on Murashige and Skoog medium containing benzylaminopurine (1.1 µM), gibberellic acid (0.3 µM), and activated charcoal (0.6%). The antioxidant phytohormones melatonin and serotonin were quantified in the field and greenhouse grown tissues of Vrinda and melatonin levels were found to be consistent in both conditions with higher serotonin levels under field conditions. This integrated approach combining the in vitro selection and propagation offers potential applications in the development of safe, effective, and novel natural health products of Tulsi, and many other medicinal plant species.Science, Irving K. Barber Faculty of (Okanagan)Non UBCReviewedFacultyResearche

Metabolomics-Guided Hypothesis Generation for Mechanisms of Intestinal Protection by Live Biotherapeutic Products

The use of live biotherapeutic products (LBPs), including single strains of beneficial probiotic bacteria or consortiums, is gaining traction as a viable option to treat inflammatory-mediated diseases like inflammatory bowel disease (IBD). However, LBPs’ persistence in the intestine is heterogeneous since many beneficial bacteria lack mechanisms to tolerate the inflammation and the oxidative stress associated with IBD. We rationalized that optimizing LBPs with enhanced colonization and persistence in the inflamed intestine would help beneficial bacteria increase their bioavailability and sustain their beneficial responses. Our lab developed two bioengineered LBPs (SBT001/BioPersist and SBT002/BioColoniz) modified to enhance colonization or persistence in the inflamed intestine. In this study, we examined colon-derived metabolites via ultra-high performance liquid chromatography-mass spectrometry in colitic mice treated with either BioPersist or BioColoniz as compared to their unmodified parent strains (Escherichia coli Nissle 1917 [EcN] and Lactobacillus reuteri, respectively) or to each other. BioPersist administration resulted in lowered concentrations of inflammatory prostaglandins, decreased stress hormones such as adrenaline and corticosterone, increased serotonin, and decreased bile acid in comparison to EcN. In comparison to BioColoniz, BioPersist increased serotonin and antioxidant production, limited bile acid accumulation, and enhanced tissue restoration via activated purine and pyrimidine metabolism. These data generated several novel hypotheses for the beneficial roles that LBPs may play during colitis.Medicine, Faculty ofNon UBCReviewedFacult

Mammalian Melatonin Agonist Pharmaceuticals Stimulate Rhomboid Proteins in Plants

Melatonin is a human neurotransmitter and plant signalling metabolite that perceives and directs plant metabolism. The mechanisms of melatonin action in plants remain undefined. We hypothesized that roots have a melatonin-specific receptor and/or transporter that can respond to melatonin-mediating pharmaceuticals. To test this hypothesis Arabidopsis seedlings were grown with melatonin pharmaceutical receptor agonists: ramelteon and tasimelteon, and/or antagonists: luzindole and 4-P-PDOT. Ramelteon was found both to mimic and competitively inhibit melatonin metabolism in plants. Due to the higher selectivity of ramelteon for the MT1 receptor type in humans, a sequence homology search for MT1 in Arabidopsis identified the rhomboid-like protein 7 (RBL7). In physiological studies, Arabidopsis rbl7 mutants were less responsive to ramelteon and melatonin. Quantum dot visualizations of the effects of ramelteon on melatonin binding to root cell membranes revealed a potential mechanism. We propose that RBL7 is a melatonin-interacting protein that directs root architecture and growth in a mechanism that is responsive to environmental factors.Science, Irving K. Barber Faculty of (Okanagan)Biology, Department of (Okanagan)Chemistry, Department of (Okanagan)ReviewedFacult