Immunochemical localization of tetrahydrocannabinol (THC) in chemically fixed glandular thrichomes ofCannabis(Cannabaceae)

Cannabis: A Treasure Trove or Pandora's Box?

“…Δ 9 -THCA also induced apoptosis in insect cells supporting the hypothesis of Δ 9 -THCA being also involved in plant defense against predators [108]. Extracellularly synthesized Δ 9 -THC seems to be bound to a cell wall component and transported to the secretory cavity with wall materials released from the disc cell wall during gland maturation [166].…”

“…This statement is further confirmed by (1) RT-PCR analyses showing that Δ 9 -THCA synthase is expressed predominantly in the disc/secretory cells of the glandular trichomes, (2) data from transgenic tobacco plants expressing Δ 9 -THCA synthase fused to green fluorescent protein showing fluorescence in the secretory cavity of glandular hairs [108], and (3) studies in insect cultures in which the recombinant Δ 9 -THCA synthase was also secreted to the medium [114]. In addition, a monoclonal antibodycolloidal gold probe for Δ 9 -THC localized this phytocannabinoid to the cell wall, the fibrillar matrix and the surface of the vesicles in the secretory cavity, the subcuticular wall and the cuticle of the trichomes [138,165,166]. At the same time, only minor amounts of Δ 9 -THC were occasionally localized to the cytoplasm (and organelles such as plastids) of the disc cells or to epidermal cells in the high pressure cryofixed-cryosubstituted [165] or chemically fixed [166] samples analyzed by TEM.…”

“…In addition, a monoclonal antibodycolloidal gold probe for Δ 9 -THC localized this phytocannabinoid to the cell wall, the fibrillar matrix and the surface of the vesicles in the secretory cavity, the subcuticular wall and the cuticle of the trichomes [138,165,166]. At the same time, only minor amounts of Δ 9 -THC were occasionally localized to the cytoplasm (and organelles such as plastids) of the disc cells or to epidermal cells in the high pressure cryofixed-cryosubstituted [165] or chemically fixed [166] samples analyzed by TEM. In line with these results, other analytical data showed that nearly all of the phytocannabinoid content of capitate-stalked glands was present in the secretory cavity [98].…”

“…do not provide spatial resolution of the different compounds at the (sub)cellular level. Therefore, immuno-localization [138,165,166], submicron confocal microscopy based on label-free coherent anti-Stokes Raman scattering [170] and fluorescence microscopy (using the bluish autofluorescence of CBCA under UV excitation) [89] can be used for in planta visualization of the phytocannabinoids. In addition, several tests and stains are available for histochemical localization and identification of phytocannabinoids.…”