tests the suitability of using mannitol as an osmoticum during experiments. Pressure probe and SiCSA techniques The expanding maize root tip Use of the cell pressure probe (Htisken et aI. , 1978) and single-cell sampling and analysis (SiCSA; Tomos Individual cells expand to many times their ongl- et aI. , 1994) provide an approach to study plant water nal length as they progress from the meristem to the and solute relations at the resolution of the individual mature zone of root tips. The expansion first accel- cell. In the case of water relations, the pressure probe erates and then...