Access To Cannabis Research Articles

Genetic evidence for speciation in Cannabis (Cannabaceae)

Sample populations of 157 Cannabis accessions of diverse geographic origin were surveyed for allozyme variation at 17 gene loci. The frequencies of 52 alleles were subjected to principal components analysis. A scatter plot revealed two major groups of accessions. The sativa gene pool includes fiber/seed landraces from Europe, Asia Minor, and Central Asia, and ruderal populations from Eastern Europe. The indica gene pool includes fiber/seed landraces from eastern Asia, narrow-leafleted drug strains from southern Asia, Africa, and Latin America, wide-leafleted drug strains from Afghanistan and Pakistan, and feral populations from India and Nepal. A third putative gene pool includes ruderal populations from Central Asia. None of the previous taxonomic concepts that were tested adequately circumscribe the sativa and indica gene pools. A polytypic concept of Cannabis is proposed, which recognizes three species, C. sativa, C. indica and C. ruderalis, and seven putative taxa.

A chemotaxonomic analysis of cannabinoid variation in Cannabis (Cannabaceae)

Cannabinoids are important chemotaxonomic markers unique to Cannabis. Previous studies show that a plant's dry-weight ratio of Δ(9)-tetrahydrocannabinol (THC) to cannabidiol (CBD) can be assigned to one of three chemotypes and that alleles B(D) and B(T) encode alloenzymes that catalyze the conversion of cannabigerol to CBD and THC, respectively. In the present study, the frequencies of B(D) and B(T) in sample populations of 157 Cannabis accessions were determined from CBD and THC banding patterns, visualized by starch gel electrophoresis. Gas chromatography was used to quantify cannabinoid levels in 96 of the same accessions. The data were interpreted with respect to previous analyses of genetic and morphological variation in the same germplasm collection. Two biotypes (infraspecific taxa of unassigned rank) of C. sativa and four biotypes of C. indica were recognized. Mean THC levels and the frequency of B(T) were significantly higher in C. indica than C. sativa. The proportion of high THC/CBD chemotype plants in most accessions assigned to C. sativa was <25% and in most accessions assigned to C. indica was >25%. Plants with relatively high levels of tetrahydrocannabivarin (THCV) and/or cannabidivarin (CBDV) were common only in C. indica. This study supports a two-species concept of Cannabis.

Attitudes and Beliefs About the Use of Cannabis for Symptom Control in a Palliative Population

ABSTRACT There is increasing support for the use of cannabis in terminal illness. Sixty-eight patients from a palliative population were surveyed for their attitudes and beliefs about the use of cannabis in terminal illness. Symptomatic patients with advanced illness were surveyed for attitudes, beliefs and symptom severity. Participants showed concern about cannabis' possible side effects and social consequences, with some significant differences between ethnic groups. Comfort with the use of cannabis for symptoms was reported by 80.9% and willingness to participate in a research study using cannabis was reported by 73.5%. Many felt cannabis was safer than morphine for pain management. Patients preferred an oral route of administration and had concerns about smoking cannabis. Despite significant concerns about using cannabis, most palliative patients were still willing to try it for symptom relief. This may have implications if cannabis access regulations are relaxed, in that access will come before clin...

Assessment of a Concentrated, High-Profile Police Operation. No Discernible Impact on Drug Availability, Price or Purity

Two weeks after the start of a major police initiative targeting drug dealing in London (described by the Metropolitan Police as a ‘spectacular success’), 174 street drug users were interviewed about drug price, availability and purity. Only seven users reported price increases for any drug, with the majority stating that there had been no change in any market features. This basic pattern was not influenced by whether the users were aware of the operation, whether they lived in the areas directly affected or by the number of different dealers that they used to purchase their drugs. Paradoxically, any perceived changes were more likely to be ‘improvements’ in the market than deterioration (i.e. lower price, greater availability and higher levels of purity). There is limited evidence from the current study to support the assertion that targeted policing will impact on the accessibility, price or quality of heroin, cannabis or crack cocaine.

Variation of Cannabis with reference to stem quality for paper pulp production

Ca. 160 Cannabis accessions were evaluated for stem quality characteristics. Stems from field trials in two years were analysed. The mass fractions of woody core, bark and primary and secondary bark fibres in the stem dry weight, and the dimensions of the wood fibres were considered most relevant for the evaluation of Cannabis germplasm as a raw material for paper pulp. The accession means for the woody core fraction ranged from 50% in fibre cultivars to 78% in wild populations, drug strains and fibre landraces. Consequently, the bark tissue, being the complementary stem fraction, ranged from 50% down to 22%. The ranges of the accession means were 8 to 27% and 0 to 14% for the fractions of primary and secondary bark fibres, respectively. The total bark fibre fraction ranged from 9 to 34%. Fibre cultivars had strongly increased fractions of primary and secondary bark fibres in comparison to wild populations, drug strains and fibre landraces. The levels of the assessed stem fractions were stable over years. Significant differences in wood fibre length among accessions were only detected in one of the two trials. The accession means in this trial ranged from 433 to 613 μm. For wood fibre width the accession means ranged from 24 to 37 μm and from 25 to 41 μm in the two trials, respectively. The stability of wood fibre dimensions over years was low. Within accessions, the wood fibres of male plants were usually somewhat shorter and wider than those of females. Apart from this difference between sexes there was little variation for wood fibre dimensions among individual plants within accessions. Breeding for improved woody core quality is considered not very promising. The best way for genetic improvement of hemp pulping quality is continuous selection for increased bark fibre content, which implies a reduction of the woody core fraction.

Evaluation and verification of resistance to Meloidogyne hapla Chitwood in a Cannabis germplasm collection

A collection of Cannabis accessions was evaluated for resistance to the root-knot nematode Meloidogyne hapla Chitwood in a seedling test. After inoculation with a larval suspension, significant variation was found for the number of galls and egg masses on the seedling roots. These parameters were considered as estimates for nematode infection and larval multiplication, respectively. A subset of the tested accessions was grown on a naturally infested arable field to study the relation between the test results and host characteristics in the field. The ranking order of accessions for the number of galls in the seedling test agreed well with that for the number of root galls on juvenile plants in the field. Therefore the test provides a useful indication for nematode infection. The number of egg masses in the seedling test and the population density of Meloidogyne measured in post-treatment soil samples of the field trial, showed a comparable ranking of accessions. Differences between accessions in the field were however smaller and not statistically significant.

Characterisation of Cannabis accessions with regard to cannabinoid content in relation to other plant characters

Ninety seven Cannabis accessions were evaluated for cannabinoid content and non-chemical plant characters. Variation within populations for cannabinoid content, and consistency of chemical characters at the population level were investigated. The relationship between chemical and other plant characters was very limited. Leaflet width and phenological data can be used for a rough prediction of the chemical phenotype on a population level. Various combinations of cannabinoid content and other economic plant characters were observed, thus a breeding programme will not be hampered by strict linkage. For a selection programme a direct analysis of cannabinoids will be inevitable.

The CPRO Cannabis germplasm collection

A collection of more than a 150 Cannabis accessions is being established as a source for evaluation and breeding experiments. Origin of the accessions and maintenance of the collection are described.