Yang, Yingzhen , Costa, Alex , Schroeder, Julian .
A strong Arabidopsis guard cell promoter.
One common problem in guard cell signaling research is that it is difficult to obtain consistent high expression of transgenes of interest in Arabidopsis guard cells using known guard cell promoters or the constitutive 35S cauliflower mosaic virus promoter. An additional drawback of the 35S promoter is that constitutively expressing a gene could cause pleiotropic effects. To improve the targeted expression of genes in guard cells, we isolated strong guard cell promoter candidates. Among the promoters we analyzed, one promoter drives very strong guard cell reporter gene expression including GUS (beta-glucuronidase) and yellow cameleon (GFP-based calcium FRET reporter). The expression of yellow cameleon was sufficiently strong to resolve repetitive calcium transients in guard cells of intact plants. Besides guard cells in leaves, the reporter gene is also expressed in guard cells in leaf petioles, floral stems, sepals, and carpels. Reporter gene expression is weaker in immature guard cells and also in aged plant tissues. The expression may not be entirely specific to guard cells, as we sometimes observed apparent reporter expression in epidermal cells at lower levels. To further analyze the relative promoter specificity to guard cell, we transformed the reporter construct into guard cell development mutants including too-many-mouths (tmm-1) and four-lips (flp-1). The clustered guard cell GUS staining in tmm-1 further shows that this promoter targets expression to guard cells. A serial deletion of the promoter was also pursued and a guard cell expression promoter region was defined.
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1 - University of California, San Diego, Cell and Developmental Biology Section, Division of Biological Sciences, 9500 Gilman Drive, La Jolla, CA, 92093-0116, USA
2 - University of California, San Diego, Cell and Developmental Biology Section, Division of Biological Sciences
Presentation Type: ASPB Minisymposium
Location: Continental A/Hilton
Date: Monday, July 9th, 2007
Time: 11:05 AM