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First published online April 8, 2005; 10.1104/pp.104.054809 Plant Physiology 138:153-160 (2005) © 2005 American Society of Plant Biologists STIG1 Controls Exudate Secretion in the Pistil of Petunia and Tobacco1,[w]Plant Cell Biology (T.V., R.F., M.W.-A., J.D., C.M.) and Plant Genetics (T.G.), Department of Experimental Botany, Radboud University, 6525 ED Nijmegen, The Netherlands; and Department of Plant Biology and Forest Genetics, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden (J.E.)
The lipid-rich, sticky exudate covering the stigma of solanaceous species such as tobacco (Nicotiana tabacum) and petunia (Petunia hybrida) contains several proteins, of which only some have been characterized to date. Proteome analysis of the stigmatic exudate in both species revealed the presence of a cysteine-rich, slightly acidic 12-kD protein called stigma-specific protein 1 (STIG1). In both tobacco and petunia, Stig1 is highly expressed at the mRNA level in very young and developing flowers, whereas hardly any Stig1 transcript is detected in mature flowers. This expression pattern coincides with the differentiation of the secretory zone, forming the intercellular spaces into which the exudate is secreted. Using reverse genetics, we show that STIG1 is involved in the secretion and merging of exudate lipids in the intercellular spaces of the secretory zone and that plants lacking STIG1 show an accelerated deposition of exudate onto the stigmatic surface. This phenotype was observed both in a petunia knockout mutant and in tobacco transgenic plants. We therefore propose that STIG1 plays a role in the temporal regulation of the essential exudate secretion onto the stigma.
1 This work was supported by the European Union Training Network TIPNET (grant no. HPRNCT200200265 to T.V.). J.E. received financial support from the Carl Trygger Foundation and The Swedish Research Council. [w] The online version of this article contains Web-only data. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.104.054809. * Corresponding author; e-mail c.mariani{at}science.ru.nl; fax 31243652490. Received October 13, 2004; returned for revision January 21, 2005; accepted February 10, 2005. This article has been cited by other articles:
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