NASCArrays Information at The BAR

Welcome to NASCArrays information at the BAR. This page hosts meta-information from the NASCArrays service (2002-2013). This information was parsed from text files available on the NASCArrays site. NASCArrays data is on iPlant server. To download experiment data from iPlant, please click on the experiment number. To download the CEL files, please click on the ftp link.

Description:Synopsis. Sucrose (suc) concentration in the guard-cell (gc) apoplast depends on environmental and physiological parameters, suggesting that it may be a signaling molecule that regulates gc gene expression to balance transpiration and photosynthesis. In collaboration with the lab of Dr. George W. Bates (Bio, FSU), our initial study will examine effects of suc on gene expression in leaf slices, and will be followed by gc studies at a later date.Rationale and Purpose. In apoplastic phloem loaders such as Arabidopsis, suc is excreted from the mesophyll into the apoplast. Then, suc diffuses to the phloem, where it is taken up by H+-suc co-transport. These facts imply that the apoplastic suc concentration is heterogeneous and depends on the rates of photosynthesis and translocation. Additionally, suc reaches 200 mM in the gc apoplast because of evaporation from this site. Therefore, the osmotic effect of external suc decreases stomatal aperture size when transpiration is high and CO2 is not limiting.Suc is a known regulator of gene expression. We propose that leaves adapt to a particular environment through suc (and ABA) regulation of gc gene expression. As an example, high external suc should depress gc Calvin-Cycle activity, avoiding an elevation of P-glycerate that would stimulate starch biosynthesis. In this way, gc starch degradation proceeds in light, releasing the H+ (via malate synthesis) that balance the H+ extruded during stomatal opening. As implied above, suc would affect gc gene expression in an environment conducive to high rates of photosynthesis and transpiration. However, gc are interspersed with other cells and the ordinary means of cell isolation (protoplasts, 'isolated' gc on epidermal strips) would confound an interpretation of transpiration-linked gc gene expression. As a first step, we therefore propose to study suc control of gene expression in leaf strips. These data will provide a baseline for future studies of gc specific gene expression.Plant Tissues. Ecotype Columbia will be grown at 20ºC under a 16-h photoperiod to promote large leaf size. Low light (150 µmol·m-2·s-1) and high humidity (80% RH) during leaf development will be maintained to minimize leaf apoplastic suc. Leaf strips, 2-mm wide, will be vacuum infiltrated with 5 mM PO42- (pH 6.1), 0.1 mM Ca2+ and ± 150 mM sucrose. After incubation for 4 h with aerated solution, leaf strips will be harvested and RNA will be isolated.
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Slide Information:
Slide IDSlide NameGenetic BackgroundTissueStock CodeCel File