Cannabis Glandular Trichomes: A Cellular Metabolite Factory

Abstract

Cannabis has been legalized for recreational use in several countries and medical use is authorized in an expanding list of countries; markets are growing internationally, causing an increase in demand for high quality products with well-defined properties. The key compounds of Cannabis plants are cannabinoids, which are produced by stalked glandular trichomes located on female flowers. These trichomes produce resin that contains cannabinoids, such as tetrahydrocannabinolic acid and cannabidiolic acid, and an array of other secondary metabolites of varying degrees of commercial interest. While growers tend to focus on improving whole flower yields, our understanding of the “goldmines” of the plant – the trichomes – is limited despite their being the true source of revenue for a multi-billion-dollar industry. This review aims to provide an overview of our current understanding of cannabis glandular trichomes and their metabolite products in order to identify current gaps in knowledge and to outline future research directions.

Applications of cell- and tissue-specific ‘omics to improve plant productivity

“…Cannabis sativa exhibits remarkable specialised metabolite diversity and is currently the focus of much attention from the pharmaceutical industry, breeders and researchers. It is a prolific producer of cannabinoids and terpenes in specialised structures called capitate stalked glandular trichomes ( Figure 2a ) [ 25 , 42 ]. Over 120 cannabinoids have been identified, amongst which Δ 9 -tetrahydrocannabinol and cannabidiol are the most abundant and of primary interest to the community [ 43 , 44 ].…”

“…Over 120 cannabinoids have been identified, amongst which Δ 9 -tetrahydrocannabinol and cannabidiol are the most abundant and of primary interest to the community [ 43 , 44 ]. More than 100 terpenes have been reported, but are largely understudied compared with the cannabinoids [ 42 , 45 ]. Proteomics has been successfully used to identify several hundreds of proteins in individual cannabis tissues, including the glandular trichomes, some of which are involved in the biosynthesis of secondary metabolites [ 46 , 47 ].…”

Cannabis sativa L.: Crop Management and Abiotic Factors That Affect Phytocannabinoid Production

“…Morphologically, the inflorescences of male dioecious plants are characterized by hanging panicles with few or no leaves, and inflorescences of female plants bear racemes with leafy bracts [17,18]. Female plants have the highest phytocannabinoid production due to a higher density of glandular trichomes, where these compounds are synthesized and stored [19][20][21][22]. In addition, male and hermaphroditic plants have reduced floral biomass and, thus, reduced phytocannabinoid yield [23].…”

Analysis of Morphological Traits, Cannabinoid Profiles, THCAS Gene Sequences, and Photosynthesis in Wide and Narrow Leaflet High-Cannabidiol Breeding Populations of Medical Cannabis

“…They contain high levels of plant cannabinoids, of which cannabidiol (CBD) and THC are the most abundant and pharmaceutically most important ( Friedman et al, 2019 ). They are produced in secretory cells within glandular trichomes as carboxylic acids cannabidiolic acid (CBD-A) and Δ9-tetrahydrocannabinolic acid (Δ9-THC-A) that are decarboxylated to their corresponding neutral forms CBD and THC, respectively, upon heating ( Salami et al, 2020 ; Tanney et al, 2021 ). Medical cannabis varieties contain higher amounts of THC than the legal national limits for hemp and can be grown indoors or outdoors only in compliance with strict national legal restrictions.…”