|Description of Trichomes:
Glandular secreting trichomes (GST).
Five kinds of glandular trichomes have been found in tomato species, which are Type I, large with multicelluar base; Type III, intermediate in size with a single basal cell; Type V, short, slender, 1-4 celled; Type VI, short with a 2-4 celled glandular head and Type VII, 0.05-0.1 mm smaller glandular hairs with a 4-8 celled glandular head (Reeves 1977).
Type VI trichomes are particularly abundant on the leaves and stems of the cultivated species Solanum lycopersicum (formerly Lycopersicon esculentum) and its wild relative Solanum habrochaites (formerly Lycopersicon hirsutum) f. typicum LA1777 (Gianfagna et al., 1992). They have been shown to accumulate monoterpenes in S. lycopersicum and very high levels of sesquiterpenes, mostly in the form of insecticidal carboxylic acid derivatives, in LA1777 (Coates et al., 1988, Frelichowski and Juvik, 2001; Li et al., 2004). Both species have greatly diverged in the types and amounts of terpenoids they accumulate in trichomes: S. lycopersicum mainly produces monoterpenes and traces of cI-Ss, whereas S. habrochaites var. LA1777 produces mainly cII-S carboxylic acids, small amounts of cI-Ss, and traces of monoterpenes.
Class I sesquiterpenes (cI-Ss) comprises germacrenes as well as alpha-humulene and beta-caryophyllene and class II sesquiterpenes (cII-Ss) comprises alpha-santalene, alpha-bergamotene, and beta-bergamotene.
1) Alvin F. Reeves II. (1977) Tomato trichomes and mutation affacting their development. Amer. J. Bot. 64(2): 186-189.
2) Gianfagna TJ, Carter CD, Sacalis JN (1992) Temperature and photoperiod influence trichome density and sesquiterpene content of Lycopersicon hirsutum f. hirsutum. Plant Physiol 100: 1403-1405
3) Katrin Besser, Andrea Harper, Nicholas Welsby, Ines Schauvinhold, Stephen Slocombe, Yi Li, Richard A. Dixon and Pierre Broun. (2009) Divergent Regulation of Terpenoid Metabolism in the Trichomes of Wild and Cultivated Tomato Species. Plant Physiology 149:499-514.
4) Li L, Zhao Y, McCaig BC, Wingerd BA, Wang J, Whalon ME, Pichersky E, Howe GA (2004) The tomato homolog of CORONATINE-INSENSITIVE1 is required for the maternal control of seed maturation, jasmonate-signaled defense responses, and glandular trichome development. Plant Cell 16: 126-143.