Immunochemical localization of Tetrahydrocannabinol (THC) in Cryofixed Glandular Trichomes of Cannabis (Cannabaceae)

Abstract

Delta 9-tetrahydrocannabinol (THC) localization in glandular trichomes and bracteal tissues of Cannabis, prepared by high pressure cryofixation-cryosubstitution, was examined with a monoclonal antibody-colloidal gold probe by electron microscopy (EM). The antibody detected THC in the outer wall of disc cells during the presecretory cavity phase of gland development. Upon formation of the secretory cavity, the immunolabel detected THC in the disc cell wall facing the cavity as well as the subcuticular wall and cuticle throughout development of the secretory cavity. THC was detected in the fibrillar matrix associated with the disc cell and with this matrix in the secretory cavity. The antibody identified THC on the surface of secretory vesicles, but not in the secretory vesicles. Gold label also was localized in the anticlinal walls between adjacent disc cells and in the wall of dermal and mesophyll cells of the bract. Grains were absent or detected only occasionally in the cytoplasm of disc or other cells of the bract. No THC was detected in controls. These results indicate THC to be a natural product secreted particularly from disc cells and accumulated in the cell wall, the fibrillar matrix and surface feature of vesicles in the secretory cavity, the subcuticular wall, and the cuticle of glandular trichomes. THC, among other chemicals, accumulated in the cuticle may serve as a plant recognition signal to other organisms in the environment.

Trichomes that secrete substances of a mixed nature in the vegetative and reproductive organs of some species of Moraceae

“…This is due more to the lack of tests to detect alkaloids on the trichome exudate in Moraceae, than to the absence of this substance which is considered recurrent in urticalean rosids (Levin 1976). Therefore, for Moraceae species and Cannabis sativa (Cannabaceae), trichomes and laticifers are the structures responsible for the secretion of alkaloids (present study; Furr & Mahlberg 1981;Lanyon et al 1981;Kim & Mahlberg 1997;Konno et al 2006;Araújo et al 2014), whereas in Urticaceae alkaloids have been identified in urticant emergences (Thurston & Lersten 1969).…”

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

“…In contrast, little or no label was present in the cytoplasm of cells. The distribution pattern in tissues prepared by two different techniques suggests that minimal redistribution and, possibly, extraction occurred during tissue processing (Kim and Mahlberg, 1997b). The HPC-CS procedure has been used successfully to preserve proteoglycans and other aqueoussoluble cell components in animal tissues (Hunziker and Schenk, 1984;Hunziker, 1993).…”

“…No antibody was detected in the cytoplasm of the disc cells. This study was conducted on tissues prepared by high pressure cryofixation-cryosubstitution (HPC-CS) to minimize the possible redistribution of cannabinoids during the fixation process (Kim and Mahlberg, 1997b). It was pertinent that the label was associated with the cell wall, the wall-derived fibrillar matrix and the surface feature of vesicles, and did not occur in secretory vesicles in the cavity or in the disc cell cytoplasm.…”

Structural Features of Glandular and Non-glandular Trichomes in Three Species of Mentha

“…In many cases, such trichomes are living cells whereas in others they are dead and the protoplasm is replaced by air spaces (Fahn, 1988 (Kolalite, 1998). Glandular trichomes are generally accepted as the functionally specialized tissues that produce various secondary metabolites, which are then stored or volatilized at the plant surface (Kim & Mahlberg, 1997;Mahlberg & Kim, 2004). Many plants use glandular trichomes to produce secondary compounds that are used for pollination, defense, and protection.…”