Epidermis: Outer Cell Layer of the Plant

Abstract

The epidermis is the protective outer layer of clonally related cells covering all plant organs. It is composed of a number of specialised cell types which differentiate from the basal epidermal cell in adaptively significant frequencies and patterns. The epidermis is unique in developing solely through anticlinal divisions, generating a sheet of cells overlying the rest of the plant. This sheet is connected biochemically to the cell layers below, with information exchange occurring in both directions. The specialised cell types within the epidermis develop either through communication among themselves, or, in some cases, through communication also with the underlying cell layers. Brief descriptions of the molecular genetic control of trichomes, stomata, root hairs and petal conical‐papillate epidermal cells are provided here, along with a summary of the role of the cuticle in epidermal cell morphology.

Key Concepts:

  • The plant epidermis is a single layer of clonally related cells.

  • Plant epidermis fulfils a basic protective function, but specialised cells within the epidermis have specific roles.

  • The aerial epidermis originates in the shoot apical meristem, the root epidermis in the root apical meristem and the seedling epidermis arises by isolation of the outer layer during embryogenesis.

  • Stomatal guard cells allow gas exchange, and their patterning is controlled by cell lineage‐based developmental mechanisms.

  • Trichomes protect the plant from herbivores, and their patterning is controlled by cell–cell interactions.

  • Root hairs increase surface area for water and nutrient uptake, and are patterned according to positional signals.

  • The cuticle overlying the epidermis can contribute to cell shape and function.

Keywords: trichomes; stomata; differentiation; development; patterning

Figure 1.

(a) Adaxial epidermis of tobacco leaf showing spacing of stomatal guard cells, two different types of trichome and pavement cells. (b) Adaxial epidermis of rose petal. All cells adopt the conical‐papillate form with heavy cuticular striations.

Figure 2.

Epidermal cell layers. (a) The epidermis of the shoot is derived from the L1 layer of the shoot apical meristem. Communication between different cell types in the epidermis determines their patterning. (b) The epidermis of the root is derived from a set of initials in the root apical meristem. Communication between cells within the epidermis, and signals from the cortical cells below, determine cellular differentiation. (c) The protoderm covering the embryo is formed by positional isolation (signified by the red line) from the cell layers below.

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Further Reading

Glover BJ (2000) Differentiation in plant epidermal cells. Journal of Experimental Botany 51: 497–505.

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Larkin JC, Marks MD, Nadeau J and Sack F (1997) Epidermal cell fate and patterning in leaves. Plant Cell 9: 1109–1120.

Leyser O and Day S (2002) Mechanisms in plant development. Oxford, UK: Blackwell.

Martin C and Glover BJ (2007) Functional aspects of cell patterning in aerial epidermis. Current Opinion in Plant Biology 10: 70–82.

Pesch M and Hulskamp M (2009) One, two, three…models for trichome patterning in Arabidopsis. Current Opinion in Plant Biology 12: 580–586.

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

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How to Cite close
Glover, Beverley J(Apr 2010) Epidermis: Outer Cell Layer of the Plant. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0002072.pub2]