Glandular Trichome Structure and Biosynthesis

Glandular Trichome Structure and Biosynthesis
Professor DeBacco
Research Article
Xie, Z., Mi, Y., Kong, L., Gao, M., Chen, S., Chen, W., ... & Xu, Z. (2023). Cannabis sativa: origin and history, glandular trichome development, and cannabinoid biosynthesis. Horticulture Research, 10(9), uhad150.
academic.oup.c...
Research Article
Hancock, J., Livingston, S. J., & Samuels, L. (2024). Building a biofactory: Constructing glandular trichomes in Cannabis sativa. Current Opinion in Plant Biology, 80, 102549.
www.sciencedir...
Cannabis Growth and Experimental Timelines
Cannabis exhibits a relatively short growth cycle, lasting 2-5months.
The seedling stage takes about 3-10 days post germination
Vegetative growth stage lasts about 20-30 days this is when the plant is focused on root and shoot development
The rapid growth of the upper part of the plant is maintained for 10-30 days.
Cannabis Growth and Experimental Timelines
Pre-flowering shoots as cuttings are suitable for asexual propagation.
The flowering initiation in Cannabis can be induced by subjecting the plants to short-day conditions.
After approximately a week, flowers begin to appear at the top of the branches.
The flowering phase typically lasts for a month.
Cannabis Growth and Experimental Timelines
When treated with hormones or AgNO3, female plants can be transformed into male plants.
The harvesting of inflorescences for cannabinoids is typically done when the pistils have withered and some of the trichomes are amber in color.
If female flowers are pollinated during the flowering phase, seeds can be collected after approximately a month.
New varieties with high CBD yield can be obtained through hybridization breeding or molecular breeding techniques.
Different GT Types
Note:
GT = Glandular Trichomes
Scanning electron microscopy analysis illustrating the different GT types on the surface of various tissues in Cannabis sativa.
Type I: capitate-stalked GT
Type II: capitate-sessile GT
Type III: bulbous GT
Type IV: nonsecretory GT
Regulatory Network of GT
Summarized transcriptional regulatory network of GT initiation in S.lycopersicum (tomato) and A.annua (Sweet wormwood).
Schematic model of cannabis stalked glandular trichome development
Structural diagram of Secretory GTs.
Cannabis GTs are distinctive secretory structures that are crucial in the production and reservation of cannabinoids, primarily found on the bracts and flowers of female Cannabis plants
Secretory Glandular Trichomes
The secretory GTs are known as the ‘plant chemical factory’, secreting, synthesizing, accumulating and storing multiple secondary metabolites (ex. Cannabinoids).
These structures are primarily found on the bracts and flowers of female Cannabis plants
Isolation and Analysis of Cannabis Glandular Trichomes
CBGA and THCA are produced in both bulbous GTs and stalked GTs
CBC and CBN were specifically detected in bulbous stalked GTs
Stalked GTs have a higher accumulation of mono terpenes
Based on Auto fluorescence studies
The ability of these GTs (which are small in physical size) to produce and secrete significant quantities of secondary metabolites remains a mystery.
Trichome Development
The first step in cannabis glandular trichome development is the differentiation of a protodermal cell to trigger a series of cell divisions resulting in an epidermal outgrowth
The exact regulatory mechanisms that trigger the developmental trajectory of protodermal cells in cannabis is unknown;
*Other species, like Solanum lycopersicum (Tomato) and Artemisia annua, (Sweet wormwood) may provide useful comparisons
Cannabinoid and Terpene Biosynthesis
The secretory disc cells form an interconnected syncytium, responsible for cannabinoid and terpene biosynthesis, transport, and storage
Syncytium- a single cell or cytoplasmic mass containing several nuclei, formed by fusion of cells or by division of nuclei.
Formation of the storage cavity will occur through delamination of the cell wall.
Extracellular Storage
Cannabinoid and terpenoid products are warehoused in the extracellular storage cavity.
These compounds are stored essentially outside and away from the plant.
Finally, multicellular stalks raise the glandular heads above the epidermis, giving cannabis flower their frosty appearance.
Trichomes Maturity
Microscopy showed that once trichomes have reached maturity, turning an amber color, resin droplets are secreted on the surface of the glandular head, and the cuticle collapses inward
Link to Lecture Slides: drive.google.c...
*Due to the description character limit the full work cited for "Glandular Trichome Structure and Biosynthesis" can be viewed at... docs.google.co...