No abstract

In Europe, more than 50 approved cultivars of fiber hemp (Cannabis sativa L.) are in agricultural production. Their content of psychoactive tetrahydrocannabinol (THC) is legally restricted to <0.2% (%w/w in the dry, mature inflorescences). Cannabis strains with much higher THC contents are also grown, illegally or under license for drug production. Differentiation between these two groups relies on biochemical quantification of cannabinoid contents in mature floral material. For nonflowering material or tissue devoid of cannabinoids, the genetic prediction of the chemical phenotype (chemotype) provides a suitable method of distinction. Three discrete chemotypes, depending on the ratio of THC and the noneuphoric cannabidiol (CBD), can be distinguished: a "THC-predominant" type, a "CBD-predominant" type, and an intermediate chemotype. We present a systematic genetic prediction of chemotypes of 62 agricultural hemp cultivars grown in Europe. The survey reveals the presence of up to 35% B T allele-carrying individuals (representing either a THC-predominant or an intermediate chemotype) in some cultivars-which is unexpected considering the legal THC limit of 0.2% THC. The fact that 100% of the seized drug-type seeds in this study revealed at least one B T allele, reflects that plant breeding efforts have resulted in a fixation of the B T allele in recreational Cannabis. To guarantee a sincere forensic application based on a genetic chemotype prediction, we recommend not to classify material of unknown origin if the samples size is below nine genetically independent individuals.In Europe, more than 50 agricultural hemp cultivars are grown and should contain <0.2% (w/w) of Δ 9 -tetrahydrocannabinol (THC), their main psychoactive cannabinoid constituent, in the mature dry inflorescences. Additionally, numerous strains with a THC content of up to 20-25% are grown for drug production. Differentiation between these two groups relies on the quantitative biochemical assessment of cannabinoid contents and ratios in mature floral material. For nonflowering material (e.g., very young seedlings) or material devoid of cannabinoids (seeds and roots), the genetic assessment of the chemical phenotype (chemotype) provides an alternative and quick means of differentiation (1).The ratio of THC and the noneuphoric cannabidiol (CBD) remains constant throughout the plant´s life and is not affected by external factors (2-4). Based on the CBD/THC ratio, three discrete chemotypes can be distinguished: a THC-predominant type (CBD/THC ratio 0.00-0.05), a CBD-predominant type (CBD/THC ratio 15-25), and an intermediate phenotype (CBD/ THC ratio 0.5-3). The CBD/THC ratio appears to be under the control of a simple inheritance mechanism. According to a model by (5), it is determined by a single locus (B) with two codominant alleles (B T and B D ). The homozygous B T /B T genotype underlies the THC-predominant phenotype, and B D /B D is CBD-predominant. The intermediate phenotype is induced by the heterozygous state (B T /B D ).Through a linkage stu...