The legal status of cannabis is changing in many countries, but because it was prohibited for the past century, research is lacking on basic aspects of this crop species. In order to support cannabis production, for the medicinal and recreational markets, scientific research needs to expand in three main areas: 1) cannabis genomics, 2) cannabis breeding and 3) cannabis production systems. The expansion of knowledge related to cannabis genomics will provide insight into the genetic diversity of cannabis that is currently available, both in the market and in the wild. To date, several studies have examined the genetic structure of marijuana and hemp, largely for the purposes of forensic investigations. However, this area of research can be expanded, using modern tools, to provide insight into how genotypic variation is related to the phenotypic presentation through genome-wide association studies (GWAS); this knowledge could be applied in future breeding programs for both hemp and marijuana. Most marijuana breeding has been conducted by the black market; however, recently several medical marijuana companies have begun intensive breeding programs to produce marijuana strains with desirable attributes for medicinal purposes. However, the question of genetic stabilization remains open since this plant is dioecious and the registration of cultivars has not yet been undertaken.
On the production side, there is a need to understand the impact of growth conditions that impact total biomass generation and, more importantly, the production (both composition and quantity) of cannabinoids produced. This could include things such as nutrient regime, water availability, light quantity and quality, the effects of stressors such as agitation and shifts in orientation. In addition, there can be significant challenges with regard to control of plant pathogens. These can reduce output and potentially change chemotype. In addition, application of cidal compounds to control pathogens has the capacity to leave residues in the materials finally made available to consumers.
Plants always exist in a close relationship with a community of microbes (the phytomicrobiome); the phytomicrobiome plus the plant constitute the holobiont, the entity the provides productivity and that evolution acts on. These microbes have been shown to produce signal compounds that, at very low concentration, excert dramatic effects on plant growth and stress responses. Members of the phytomicrobiome also protect the plant host against disease organisms. This area has received minimal investigation for cannabis. Because cannabis is often grown under controlled environment conditions the ability to manipulate the phytomicorbiome is large and this could result in effective disease control, specific shifts in the chemotype and greater overall production.
The scope of the Research Topic extends to include manuscripts relevant to cannabis genomics, breeding, production, and policy. We are most interested in manuscripts containing original research, given the low availability of this data in the scientific literature. We will also consider review papers related to management, genetics, and breeding.
We are interested in specific topics, such as:
• History, domestication, social perspectives: Ethnobotany
• Management and production: Chemistry of cannabis, Total potential capacity, and demand, Light (intensity, quality, photoperiod), Nutrient management, cannabinoid accumulation during growth, elicitation, Temperature, CO
2, propagation, Production equipment, systems, Plant-microbe interactions (pathogens, beneficial, elicitation), Water use & environmental impact
• Genetics/genomics: Inheritance of chemical phenotype, Metabolic response to environmental conditions, Population genetics (domestication, cannabis, hemp, herbal, wild, germplasm), Breeding (crop improvement through polyploids), Synthetic biology
• Fibre hemp: Crop overview & field production, Breeding
• Policy: Canadian, US, and international laws
Important Note: Studies with the specific aim to either improve local healthcare by developing products based on such knowledge or studies in the context of drug discovery/development from natural sources will be considered if they are based on biological resources with a clear and well-defined local or traditional use. Purely biodiversity-based screening studies and studies of established natural products and their mechanism of action are outside the scope of this section. Studies reporting such local and traditional uses will only be accepted if the comply with the ConSEFS standards (
Heinrich et al. 2017). Toxicological research and clinical studies on medicinal plants are welcome.
The following basic guidelines, focused on best practice in ethnopharmacology, should be followed by all submissions:
•
Botanical - The
Etnopharmachology Specialty Section of
Frontiers in Pharmacology subscribes to the taxonomic standards laid down most importantly at the
Kew MPNS portal and also the Royal Botanic Gardens/Kew/Missouri Botanical Garden
"The Plant List" initiative. Of course, full botanical documentation is essential (i.e. a voucher specimen deposited in a recognized herbarium).
•
Pharmacological - Antioxidant activity: here in vivo or in vitro studies using generally acceptable pharmaceutical models are essential. Simple in silico and pharmacologically irrelevant assays for antioxidant activity (e.g. the DPPH assay, FRAP (Ferric Reducing Ability of Plasma), ABTS (2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) are not acceptable as a main tool for assessing an extract or a compound for activity. Such assays are commonly used in food chemistry and other fields, but are not of pharmacological relevance.
- Dose ranges must be pharmacologically relevant. While impossible to define an exact cut-off, studies testing extracts at implausibly high doses are increasingly common in the literature.
- Positive and negative controls must be included.
- Models must be pharmacologically relevant and plausible - a complex issue depending on the specific goals of the study. Authors must consider the ethical acceptability of further
in vivo studies on an already well-studied species, demonstrating some common activity (e.g. an anti-inflammatory effect studied in the rat-paw oedema).
•
Chemical - The composition of the study material must be described in sufficient detail.
- If 'pure' compounds are used information on the level of purity must be included.
In case of ethnopharmacological field studies you must follow the
ConSEFS standards.
