The inheritance of chemical phenotype in Cannabis sativa L. (II): Cannabigerol predominant plants

Abstract

This paper aims to clarify the genetic mechanism that is responsible for the accumulation of cannabigerol (CBG) in certain phenotypes of Cannabis sativa L. CBG is the direct precursor of the cannabinoids CBD, THC and CBC. Plants strongly predominant in CBG have been found in different fibre hemp accessions. Inbred offspring derived from one such individual were crossed with true breeding THC predominant-and CBD predominant plants, respectively. The segregations in the cross progenies indicate that CBG accumulation is due to the homozygous presence of a minimally functional allele, tentatively called B 0 , at the single locus B that normally controls the conversion of CBG into THC (allele B T ) and/or CBD (allele B D ). The fact that CBG accumulating plants have so far been found in European fibre hemp populations that are generally composed of B D /B D plants, and the observation that the here investigated B 0 allele possesses a residual ability to convert small amounts of CBG into CBD, make it plausible that this B 0 is a mutation of normally functional B D . Therefore, B 0 is considered as a member of the B D allelic series encoding a CBD synthase isoform with greatly weakened substrate affinity and/or catalytic capacity.

Genomic and Chemical Diversity inCannabis

“…However more recent quantitative trait loci (QTL) mapping experiments (Weiblen et al, 2015), expression studies (Onofri et al, 2015), and genomic analyses (van Bakel et al, 2011) paint a more complex scenario with several linked paralogs responsible for the various THCA and CBDA phenotypes. Other cannabinoids such as cannabigerol (CBG) (Borrelli et al, 2014), cannabichromene (CBC) (Izzo et al, 2012), and delta-9-tetrahydrocannabivarin (THCV) (Mcpartland et al, 2015) demonstrate pharmacological promise, and can also be produced at high levels by the plant (de Meijer and Hammond, 2005;de Meijer and Hammond, 2016;de Meijer et al, 2008). Additionally, Cannabis secondary metabolites such as terpenoids and flavonoids likely contribute to therapeutic or psychoactive effects (Russo, 2011).…”

Classification of Cannabis Cultivars Marketed in Canada for Medical Purposes by Quantification of Cannabinoids and Terpenes Using HPLC-DAD and GC-MS

“…The first, a botanical perspective, attempts to classify cannabis into different species or subspecies based on appearance, THC content, and geographical origins (gene pools) [8][9][10][11][12][13]. The second, a chemotaxonomic perspective, describes five chemotypes (chemical phenotypes) based on the ratio of two major cannabinoids THC and CBD, which is decided by their corresponding allelic loci [14][15][16][17][18][19][20][21]. Recently, a third perspective seeks to categorize cultivars based on both cannabinoids and terpenes for drug standardization and clinical research purposes [22,23].…”

Chemistry and Biological Activity of Tetrahydrocannabinol and its Derivatives

“…By combining the phenotypes of various plants with each other, a plant could be grown that is large in growth, high in glandular trichoma density, or high in THCA content. Through breeding techniques Meijer et al [54] have already created a high CBGA-producing plant and in the drug culture the same has been reached for THCA [59]. In the latter, preparations were found containing more than 20% THC, while in the literature and exported Cannabis the normal values lie at 6-10%.…”

“…These three chemotypes consist of the "fiber"-type (CBD > THC), the "intermediate"-type (CBD≈THC) and the "drug"-type (CBD < THC). The chemotypes have been recently shown to be dependent either on one locus on the chromosome, or two closely linked loci [47], but the former theory is the most likely one [52][53][54]. The locus is called the B locus and until now it is proven to consist of at least two alleles, namely B t and B d .…”

“…There is also an indication for a third allele. This one was named B 0 and seems to be responsible for a CBGA-dominant chemotype [54]. The alleles, B t and B d , show co-dominance and the B 0 allele is recessive or an inactive B d allele.…”