In mature plant cells, up to 90% of the cell volume is occupied by the central vacuole, which represents a storage compartment for proteins, metabolites and many charged nutrients (ions). Most of the ions that are taken up by plants are stored in the vacuole, but under certain conditions these ions also can be released back into the cell sap (cytosol). Despite of importance of vacuoles for plant growth and development, little is known about the mechanisms that regulate the ion transport proteins in vacuolar membrane.
We have developed a method to study the activity of ion channels in the vacuolar membrane of intact cells (Wang et al., 2015, see also Fig.). This method was used to study the role oft he vacuole in the regulation of the calcium homeostasis in root hair cells (Dindas et al., 2021). We found that calcium was taken up into vacuoles by a transport mechanisms that was linked to the difference in acidity between the vacuole and cytosol (pH gradient). This method will be further developed to unravel the molecular mechanisms that are utilized by plants cells to control nutrient storage in the vacuole.