Optimizing medical marijuana: developing genetic and chemical resources to improve the quality and quantity of cannabinoid metabolites in Cannabis sativa L strains
Cannabinoids are synthesized and accumulate in Cannabis plant hairs called glandular trichomes, which are particularly abundant on female flower buds. Cannabinoid content and composition vary dramatically among Cannabis strains, with two general groupings distinguished: marijuana strains, defined by high THC and low CBD levels, and hemp strains containing low THC and high CBD (or low total cannabinoid content). Marijuana breeding efforts have increased the cannabinoid potency and profiles of cannabis strains, and have produced marijuana strains with highly variable chemical phenotypes (chemotypes). While these breeding efforts have been successful in dramatically increasing THC levels, they commonly have reduced the content of other pharmaceutically valuable cannabinoids that compete for overlapping starter substrates (4). Many cannabinoids are known to have important pharmacological properties, and the relative abundance of the major cannabinoids (THC, CBD and CBC), minor cannabinoids and terpenoids can alter the therapeutic effects of marijuana strains. For instance, the presence of CBC augments some of the pharmacological effects of THC, while CBD has the ability to reduce THC side effects (5, 6). Metabolic profiling efforts proposed here will determine which cannabinoids accumulate in the female flowers of select medical marijuana strains, and the relative abundance of these cannabinoids in each strain.