Journal Article

Expression analysis of <i>Arabidopsis</i> vacuolar sorting receptor 3 reveals a putative function in guard cells

Emily L. Avila, Michelle Brown, Songqin Pan, Radhika Desikan, Steven J. Neill, Thomas Girke, Marci Surpin and Natasha V. Raikhel

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 59, issue 6, pages 1149-1161
Published in print April 2008 | ISSN: 0022-0957
Published online April 2008 | e-ISSN: 1460-2431 | DOI: https://dx.doi.org/10.1093/jxb/ern025

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Vacuolar sorting receptors (VSRs) are responsible for the proper targeting of soluble cargo proteins to their destination compartments. The Arabidopsis genome encodes seven VSRs. In this work, the spatio-temporal expression of one of the members of this gene family, AtVSR3, was determined by RT-PCR and promoter::reporter gene fusions. AtVSR3 was expressed specifically in guard cells. Consequently, a reverse genetics approach was taken to determine the function of AtVSR3 by using RNA interference (RNAi) technology. Plants expressing little or no AtVSR3 transcript had a compressed life cycle, bolting ∼1 week earlier and senescing up to 2 weeks earlier than the wild-type parent line. While the development and distribution of stomata in AtVSR3 RNAi plants appeared normal, stomatal function was altered. The guard cells of mutant plants did not close in response to abscisic acid treatment, and the mean leaf temperatures of the RNAi plants were on average 0.8 °C lower than both wild type and another vacuolar sorting receptor mutant, atvsr1-1. Furthermore, the loss of AtVSR3 protein caused the accumulation of nitric oxide and hydrogen peroxide, signalling molecules implicated in the regulation of stomatal opening and closing. Finally, proteomics and western blot analyses of cellular proteins isolated from wild-type and AtVSR3 RNAi leaves showed that phospholipase Dγ, which may play a role in abscisic acid signalling, accumulated to higher levels in AtVSR3 RNAi guard cells. Thus, AtVSR3 may play an important role in responses to plant stress.

Keywords: Abscisic acid; expression analysis; guard cells; hydrogen peroxide; nitric oxide; phospholipase Dγ1; protein trafficking; vacuolar sorting receptor

Journal Article.  7863 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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