The abscission of organs takes place at discrete sites and at specific times during the life cycle of a plant. These observations suggest that the abscission zone comprises a layer of positionally differentiated cells that undergo separation from their neighbours in response to precise developmental and environmental cues. By studying mutants of Arabidopsis that exhibit an attenuated capacity to shed their floral organs, it has been possible to identify a number of genes that may play a role in both the differentiation of abscission zone cells and the timing of organ shedding. Recent advances in transcript profiling have also helped us unravel the changes in gene expression that accompany cell separation and further proteomic and metabolomic advancements will add to this knowledge over the coming years. The possible applications of this knowledge to agricultural and horticultural species are discussed.

Key Concepts:

  • The manipulation of abscission has been crucial during the history of agriculture and a more detailed understanding of the process could contribute to increases in both the quantity and quality of crop yield.

  • Organ shedding takes place at discrete sites termed abscission zones that are differentiated early in development.

  • The timing of organ shedding is regulated by distal tissues such as the leaf, flower or fruit.

  • The study of mutants in Arabidopsis has played a key role in identifying the genes involved in abscission zone differentiation and development.

  • The plant hormones auxin and ethylene play an important role in regulating when abscission takes place.

  • Abscission involves cell wall dissolution and the molecular and biochemical events that regulate it may account for the remodelling that takes place at other sites during plant growth and development.

Keywords: abscission zone; cell separation; auxin; ethylene; cell wall degrading enzymes; mutants; Arabidopsis

Figure 1.

Sites of abscission.

Figure 2.

Events associated with abscission in Arabidopsis and some of the genes involved.



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Further Reading

Aalen RB, Butenko MA, Stenvik GE, Tandstad NM and Patterson SE (2006) Genetic control of floral abscission. In: daSilva JT (ed.) Floriculture, Ornamental and Plant Biotechnology: Advances and Topical Issue, pp. 101–108. London: Global Science Book Ltd.

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Leslie E, Lewis MW and Liljegren SJ (2006) Organ abscission. Annual Plant Reviews 25: 106–136.

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Roberts, Jeremy A, and González‐Carranza, Zinnia H(Apr 2013) Abscission. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0020089.pub2]