Background

Isolation of guard cells for RNA extraction has traditionally relied on guard cell protoplast extraction (Leonhardt et al., 2004) or epidermal peels (Pandey et al., 2010). Manual dissection of guard cells from freeze-dried leaves has also been used (Bates et al., 2012). The protoplast procedure may introduce unwanted changes in gene expression from wounding effects and other methods are time consuming, require special equipment or expensive reagents (e.g., transcriptional inhibitors). Hence there is a need for a fast and simple protocol to isolate guard cells for gene expression analysis. Here we further describe a quick ice blender method for isolation of guard cell enriched tissue (Bauer et al., 2013), in the form of epidermal fragments without mesophyll and other vascular cells. This method uses a nylon mesh to collect epidermis from blended leaf tissue. The adequately large pore size of the nylon mesh allows mesophyll and other vascular cells to pass through while retaining the epidermal fragments. We propose that the critical factor in this protocol is the type of blender used to process the samples.