Journal Article

Ethylene and the Regulation of Senescence Processes in Transgenic <i>Nicotiana sylvestris</i> Plants

Thomas F. Yang, Zinnia H. Gonzalez-Carranza, Martin J. Maunders and Jeremy A. Roberts

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 101, issue 2, pages 301-310
Published in print January 2008 | ISSN: 0305-7364
Published online September 2007 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcm229
Ethylene and the Regulation of Senescence Processes in Transgenic Nicotiana sylvestris Plants

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  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry

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Background and Aims

Exposure of plants to ethylene can influence a spectrum of developmental processes including organ senescence and abscission. The aim of this study was to examine the role of the gaseous regulator in Nicotiana sylvestris plants exhibiting a silenced or constitutive ethylene response.

Methods

Transgenic N. sylvestris plants were generated that either ectopically expressed the Arabidopsis mutant ethylene receptor ETR1-1 or the tomato EIN3-like (LeEIL1) gene. Highly expressing homozygous lines were selected and the time-course of development, from germination to organ senescence, was studied.

Key Results

Fifty percent of the homozygous Pro35S:ETR1-1 lines examined showed a high susceptibility to collapse prior to flowering, with plant death occurring within a few days of leaf wilting. The time-course of leaf senescence in the remaining Pro35S:ETR1-1 lines was visibly arrested compared to wild type (negative segregant) plants and this observation was reaffirmed by chlorophyll and protein analysis. Petal necrosis was also delayed in Pro35S:ETR1-1 lines and corolla abscission did not take place. When senescence of Pro35S:ETR1-1 plants did take place this was accompanied by leaf bleaching, but tissues remained fully turgid and showed no signs of collapse. A single Pro35S:LeEIL1 line was found to exhibit consistently accelerated leaf and flower senescence and precocious flower bud shedding.

Conclusions

These observations support a role for ethylene in regulating a spectrum of developmental events associated with organ senescence and tissue necrosis. Furthermore, the transgenic lines generated during this study may provide a valuable resource for exploring how senescence processes are regulated in plants.

Keywords: Nicotiana sylvestris; ethylene; senescence; chlorophyll; flower abscission; etr1-1; necrosis; pathogenesis

Journal Article.  6242 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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