Trichomes

Abstract

A ‘trichome’ (or hair) is an outgrowth derived from the shoot or root epidermis of a plant. Form and distribution of trichomes differ between plant species or genera, but molecular work reveals common regulatory pathway for development of different trichome types within the same plant species and possibly also across plant species.

Keywords: trichomes; root hairs; patterning

Figure 1.

(a) Rosette of a young Arabidopsis thaliana plant. Note the regular distribution of leaf trichomes. (b) Unicellular branched trichome of Arabis alpina. (c) Multicellular unbranched trichome of Tricyrtis hirta. (d) Glandular trichome of Pelargonium zonale. (e) Root hair of A. thaliana.

Figure 2.

Genetic model for the selection of a trichome and root hair cells in Arabidopsis. Bottom: Initially, both cells are equivalent. They express the bHLH, the R2R3 MYB factor, the WD40 protein, which activate GL2 and the R3 MYB factor. Owing to movement of the R3 MYB factor the cells compete with each other. Middle: Owing to small fluctuations the system becomes biased; here the right cell becomes specialized as indicated by its blue colour. In this cell the bHLH/R2R3MYB/WD40 complex activates GL2 and the R3 MYB factor which moves into the neighbouring cell where it replaces the R2R3 MYB factor rendering the complex inactive. Upper pictures: the specizalized cells (blue) develop into trichomes (left) and nonroot hair cells (right). Note that trichomes distribution is without reference to any other leaf structure whereas root hair position is biased such that root hairs form above clefts of cortex cells.

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Further Reading

Hulskamp M (2004) Plant trichomes: a model for cell differentiation. Nature Reviews. Molecular Cell Biology 5: 471–480.

Ishida T, Kurata T, Okada K and Wada T (2008) A genetic regulatory network in the development of trichomes and root hairs. Annual Review of Plant Biology 59: 365–386.

Pesch M and Hulskamp M (2004) Creating a two‐dimensional pattern de novo during Arabidopsis trichome and root hair initiation. Current Opinion in Genetics & Development 14: 422–427.

Serna L and Martin C (2006) Trichomes: different regulatory networks lead to convergent structures. Trends in Plant Science 11(6): 274–280.

Uphof JCT (1962) Plant Hairs. Berlin: Gebr. Bornträger.

Wagner GJ, Wang E and Shepherd RW (2004) New approaches for studying and exploiting an old protuberance, the plant trichome. Annals of Botany 93: 3–11.

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How to Cite close
Hülskamp, Martin, and Schellmann, Swen(Mar 2009) Trichomes. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0002071.pub2]