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Characterisation of an mRNA encoding a metallothionein-like protein that accumulates during ethylene-promoted abscission of Sambucus nigra L. leaflets.

Coupe, Simon A. and Taylor, Jane E. and Roberts, Jeremy A. (1995) Characterisation of an mRNA encoding a metallothionein-like protein that accumulates during ethylene-promoted abscission of Sambucus nigra L. leaflets. Planta, 197 (3). pp. 442-447.

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Abstract

A cDNA encoding a metallothionein-like protein has been isolated from a cDNA library from the abscission zones of ethylene-treated Sambucus nigra leaflets. The precise function of this group of proteins in plants has yet to be confirmed but in animals there is convincing evidence that they bind heavy metals. Several of these proteins have recently been characterised from plants and it has been demonstrated that heavy metals have no stimulatory effect on their expression. In this paper we describe the isolation and characterisation of a metallothionein-like mRNA identified as a consequence of differentially screening a cDNA library for messages up-regulated during abscission. The accumulation of the mRNA occurred in the abscission zone tissue within 18 h of exposure to ethylene while, in contrast, no expression was detectable in adjacent non-abscission-zone tissue. The transcript size of the message was approximately 0.6 kb. Northern analysis revealed that the cDNA insert (JET12) did not hybridise to mRNA from either green or senescing leaflets but a signal was detectable with mRNA extracted from senescent tissue. The size of this hybridising transcript was approximately 0.5 kb. The predicted metallothionein-like protein encoded by JET12 was cysteinerich (18.4%) and had a molecular weight of approximately 7.5 kDa. Southern analysis of S. nigra genomic DNA showed that the mRNA was encoded by a small gene family. The protein exhibited greatest homology to other metallothioneins belonging to the Type 2 family including those from Mimulus (62%) and Arabidopsis (57%). This homology was greatest around the cysteine-rich amino and carboxy termini. The possible role of the protein encoded by JET12 during ethylene-promoted leaflet abscission is discussed.

Item Type: Article
Journal or Publication Title: Planta
Uncontrolled Keywords: Abscission - Ethylene - Metallothionein-like protein - Pathogenesis - Sambucus - Senescence
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 22250
Deposited By: ep_ss_importer
Deposited On: 10 Feb 2009 12:14
Refereed?: No
Published?: Published
Last Modified: 26 Jul 2012 15:58
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/22250

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