For monitoring the cellular pH in plants, engineered green fluorescent protein (GFP) has been used to indicate cellular pH. Pt-GFP is a pH-reporter protein which has been used ratiometrically in the double excitation mode, according to the fluorescence properties described for Pt-GFP (Schulte et al., 2006), and depending on our previous experiments, we present here a little and efficient protocol for monitoring the cytosolic pH value. In this protocol, root hair cellular pH was monitored in the PtGFP reporter lines. Cellular pH can be obtained according to the calibration curve which was performed in situ by using a series pH buffer.
Stable Pt-GFP transgenic WT line N9561 (background: Col-0) was obtained from the Nottingham Arabidopsis Stock Centre http://arabidopsis.info/StockInfo?NASC_id=9561). Note: Pt-GFP T-DNA insertion mutant homozygous were obtained by crossing the T-DNA insertion mutant (what you interested, here meant the mutant with root hair growth problem) with the N9561. And we obtained the T-DNA insertion homozygous first by PCR (methods in http://signal.salk.edu/cgi-bin/tdnaexpress) in the F2 progeny, and we checked the fluorescence for Pt-GFP. Homozygous lines with fluorescence will be used for later analysis.
Digitonin (Sigma-Aldrich, catalog number: 11024-24-1 ) Note: Risk assessment: toxic. Digitonin is toxic by inhalation, contact with skin, wear protective gloves and clothing, wear respiratory protection, when handling this chemical.