Trichomes, glandular

As is the case with many members of Lamiaceae, Satureja douglasii produces abundant essential oil from glandular trichomes on the leaves. Gas chromatographic analysis of the leaf oils from specimens collected throughout the species range revealed the presence of some dozen and a half well-known compounds. The major compounds identified were camphene [215], camphor [216], which, taken together, were considered to comprise the bicyclic type, carvone [217], pulegone [218], menthone [219], and isomenthone [220] (see Fig. 2.68 for structures 215-220). The predominance of each of these major components defined a terpene type. (All compounds were observed in each of the terpene types, most in comparatively small amounts, some only as traces.)... 

King, R. R., Calhoun, L. A., and Singh, L. A. 1988. 3,4-Di-O- and 2,3,4-tri-O-acylated gluco-side esters from the glandular trichomes of non-tuberous Solanum species. Phytochemistry 27 3765-3768. 

As depicted in Fig. 3, in glandular trichoma the cannabinoids are produced in the cells but accumirlate in the secretory sac of the glandular trichomes, dissolved in the essential oil [17-21]. Here, A9-THC was found to accumulate in the cell wall, the fibrillar matrix and the surface feature of vesicles in the secretory cavity, the subcutilar wall, and the cuticula of glandular trichomes [19]. 

Fig. 3 Representation of matiu-e secretory gland originated from C. sativa. The separate compartments of the glandular trichome are clearly shown, and the places where THC accumulates. Black areas nuclei, V vacuole, L vesicle, P plastid, ER endoplasmic reticulum. Picture obtained from http //www.hempreport.com/issues/17/malhodyl7.html...

In times of less accessibility of water, the plants seem to increase the cannabinoid content. It is suggested that the plant will cover itself with the oily cannabinoids to prevent water evaporation. For instance Sharma (1975) found increased glandular trichome densities in the leaves of Cannabis grown under dry circumstances [55]. 

Fig. 1 The fluorescing images of secretory cells under luminescent microscope. A and B. Blue-fluorescing stinging and non-stinging secretory hairs of Urtica dioica, relatively on stem and leaf C and D - green-yellow-fluorescing leaf glandular trichomes of Lycopersicon esculentum and Solanum tuberosum, E. - Blue-fluorescing leaf cells of Achillea millefolium F - yellow fluoresced gland of leaf Calendula officinalis., G., H and I -secretory hairs, idioblasts and crystal on the surface on the root of Ruta graveolens, relatively.

Figure 9.1 Peppermint peltate glandular trichomes (A) scanning electron micrograph (courtesy of Dr. Glenn Turner) and (B) anatomical scheme of a cross-section.

McCASKILL, D., GERSHENZON, J., CROTEAU, R., Morphology and monoterpene biosynthetic capabilities of secretory cell clusters isolated from glandular trichomes of peppermint (Mentha x piperita L.), Planta, 1992,187, 445-454. 

GERSHENZON, J., McCASKILL, D., RAJAONARIVONY, J.I.M., MIHALIAK, C., KARP, F., CROTEAU, R., Isolation of secretory cells from plant glandular trichomes and their use in biosynthetic studies of monoterpenes and other gland products, Anal. Biochem., 1992, 200, 130-138. 

LANGE, B.M., WILDUNG, M.R., STAUBER, E.J., SANCHEZ, C., POUCHNIK, D., CROTEAU, R., Probing essential oil biosynthesis by functional evaluation of expressed sequence tags from mint glandular trichomes, Proc. Natl. Acad. Sci. USA, 2000, 97, 2934-2939. 

McCASKILL, D., CROTEAU, R., Monoterpene and sesquiterpene biosynthesis in glandular trichomes of peppermint Mentha x piperita) rely exclusively on plastid-derived isopentenyl diphosphate, Planta, 1995,197,49-56. 

Trichomes Single-celled or multicellular outgrowths of epidermal cells Produce volative oils for glandular trichomes reflect bright light in some desert plants increase boundary layer mechanically discourage predators salt secretion in some halophytes digestions in sundews... 

Ryan ID, Gregory R, Tingey WH. Phenolic oxidase activities in glandular trichomes of Solarium berthauttii. Phytochemistry 1983 21 1885-1887. 

Kowalaksi SP. Bamberg J, Tringey WM, Steffens JC. Inheritance of polyphenol oxidase in type A glandular trichomes of Solanum berthaultii. JHered 1990 81 475-478. 

Boughton AJ, Hoover K, Felton GW. (2005) Methyl jasmonate apphcation indnces increased densities of glandular trichomes on tomato, Lycopersicon esculentum. J Chem Ecol 31 2211-2216. 

Tattini, M. et al., Flavonoids accumulate in leaves and glandular trichomes of Phillyrea latifolia exposed to excess solar radiation. New. PhytoL, 148, 69, 2000. 

In medieval times, cities commonly erected walls as a protective barrier to invasion. Plants have evolved similar protective mechanisms. Thorns and nettles which repel most herbivores are two examples of protective barriers. To ward off Insect attack, plants have evolved non-glandular trichomes which act in a similar fashion. Thus, in some plants, the density, length, or branching of trichomes have been negatively correlated with insect survival (10). 

Immobilizing Chemicals. Some plants produce a sticky, gummy exudate from glandular trichomes. These exudates effectively immobilize small Insects. 

The sesquiterpene lactones In Artemesla species have been reviewed (186). Hlstochemlcal tests have shown that A. nova has. In addition to nonglandular trichomes, glandular trichomes covering 21-35% of Its leaf surface (187). These glands hold a clear fluid which contains some of the monoterpenes and all of the sesquiterpene lactones present In the leaves. 

The leaf teeth In Prunus are covered by glandular trichomes. 

A quick dip of the aerial parts in ether has been used to extract the glandular trichome contents of Salvia glutinosa (194). The main component was the triterpenol, a-amyrin. Small amounts of flavones and flavonols were also Isolated. 

The wild tomato, Lycopersicon hirsutum f, glabratum is covered with trichomes which contain 2-tridecanone. The level of this compound is much lower in the domesticated tomato, U esculentum. This exudate proved to be toxic to Manduca sexta (tobacco hornworm) and to Heliothis zea (121). The density of glandular trichomes, which secrete 2-tridecanone, was influenced... 

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