Journal Article

Tissue-specific <i>PhBPBT</i> expression is differentially regulated in response to endogenous ethylene

Richard J. Dexter, Julian C. Verdonk, Beverly A. Underwood, Kenichi Shibuya, Eric A. Schmelz and David G. Clark

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 59, issue 3, pages 609-618
Published in print February 2008 | ISSN: 0022-0957
Published online February 2008 | e-ISSN: 1460-2431 | DOI:

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Ethylene is a gaseous plant hormone involved in many physiological processes including senescence, fruit ripening, and defence. Here the effects of pollination and wound-induced ethylene signals on transcript accumulation of benzoyl CoA:benzyl alcohol/phenylethanol benzoyltransferase (PhBPBT) are shown in Petunia×hybrida cv. Mitchell ‘Diploid’ (MD). In petunia, PhBPBT is responsible for the biosynthesis of both benzyl benzoate and phenylethyl benzoate from benzyl alcohol and phenylethanol, respectively. RNAi-silenced lines, with reduced PhBPBT transcript, displayed reduced benzyl benzoate emission, and increased benzyl alcohol levels. Detailed expression analysis showed that PhBPBT is regulated by both light and an endogenous circadian rhythm, while it is also differentially regulated in response to ethylene in a tissue-specific manner. Twenty-four hours following pollination of MD flowers, expression of PhBPBT decreases in the corolla, while it increases in the ovary after 48 h. This is caused by ethylene that is emitted from the flower coinciding with fertilization as this is not observed in transgenic ethylene-insensitive plants (CaMV35S::etr1-1; 44568). Ethylene is also emitted from vegetative tissue of petunia following mechanical wounding, resulting in an increase in PhBPBT expression in the leaves where expression is normally below detection levels. Indicative of this pattern of expression, we hypothesize that PhBPBT and subsequent benzyl benzoate production is involved in defence-related processes in the corolla prior to pollination, in the ovary immediately following fertilization, and in vegetative tissue in response to wounding.

Keywords: Benzenoids; benzyl benzoate; ethylene; floral volatiles; Petunia hybrida; wounding

Journal Article.  5325 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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