Original video: https://youtu.be/__uRcK1CU1Q
To date, guard cell promoters have been examined in only a few species, primarily annual dicots. A partial segment of the potato (Solanum tuberosum) KST1 promoter (KST1 partial promoter, KST1ppro) has previously been shown to confer guard cell expression in potato, tomato (Solanum lycopersicum), citrus [Troyer citrange (C. sinensis×Poncirus trifoliata)], and Arabidopsis (Arabidopsis thaliana). Here, we describe an extensive analysis of the expression pattern of KST1ppro in eight (previously reported, as well as new) species from five different angiosperm families, including the Solanaceae and the Cucurbitaceae, Arabidopsis, the monocot barley (Hordeum vulgare), and two perennial species: grapevine (Vitis vinifera) and citrus. Using confocal imaging and three-dimensional movies, we demonstrate that KST1ppro drives guard cell expression in all of these species, making it the first dicot-originated guard cell promoter shown to be active in a monocot and the first promoter reported to confer guard cell expression in barley and cucumber (Cucumis sativus). The results presented here indicate that KST1ppro can be used to drive constitutive guard cell expression in monocots and dicots and in both annual and perennial plants. In addition, we show that the KST1ppro is active in guard cells shortly after the symmetric division of the guard mother cell and generates stable expression in mature guard cells. This allows us to follow the spatial and temporal distribution of stomata in cotyledons and true leaves.
Expression pattern of the KST1 partial promoter
KST1ppro was originally tested in potato using β-glucuronidase (GUS) as a reporter gene (Plesch et al., 2001) and was later examined using green fluorescent protein (GFP) as a reporter gene in Arabidopsis, tomato, and citrus (Kelly et al., 2013; Sade et al., 2014; Lugassi et al., 2015). To study its expression in other species, we generated transgenic lines expressing GFP under the control of the KST1ppro promoters of four additional species, tobacco, cucumber, grape, and barley, as well as potato lines expressing GFP under KST1ppro. We use the term GCGFP (an abbreviation of guard cell GFP) to refer to these lines. We also created potato GCGFP to compare with the previously described KST1ppro:GUS plants (Plesch et al., 2001). Three to ten independent transgenic lines were assayed for each of the newly introduced GCGFP species, and we conducted an in-depth search for the presence of GFP fluorescence using a sensitive confocal microscope. The independent lines of each species had the same pattern of expression. The data were displayed as standard images (Figs 1–5; Supplementary Figs S1–S3) or as a 3-D movie that provides a 360° tour within the leaf including the epidermis and mesophyll. The combined data (still images and the movie) enabled us to identify the tissues and cell types in which KST1ppro is expressed, with a high degree of confidence.
Citation: Gilor Kelly, Nitsan Lugassi, Eduard Belausov, Dalia Wolf, Belal Khamaisi, Danja Brandsma, Jayaram Kottapalli, Lena Fidel, Batsheva Ben-Zvi, Aiman Egbaria, Atiako Kwame Acheampong, Chuanlin Zheng, Etti Or, Assaf Distelfeld, Rakefet David-Schwartz, Nir Carmi, David Granot, The Solanum tuberosum KST1 partial promoter as a tool for guard cell expression in multiple plant species, Journal of Experimental Botany, Volume 68, Issue 11, 17 May 2017, Pages 2885–2897, https://doi.org/10.1093/jxb/erx159
Published: 22 May 2017.
Attribution 4.0 International — CC BY 4.0 - Creative Commons
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