Ion Transport in Aquatic Plants

Abstract

Aquatic higher plants have morphologically and physiologically adapted to their water environment. Similar to terrestrial plants that have been exposed to waterlogging and inundation, aquatic plants form aerenchyma that allows gas exchange in submerged organs. Additionally, to prevent gas and solute loss, aquatic plants have developed impermeable barriers in the cells and tissues, such as suberinisation of the cell walls. In addition to the roots, the major organ for nutrient acquisition in the terrestrial plants, aquatic plants have also developed the unique ability to take up ions via leaves or shoots. This chapter summarises findings on ion transport systems in aquatic plants. Most of the ion transport systems that are located in the plasma membranes share similarities with both aquatic and terrestrial plants. To date, only one system (Na+/NO 3 − transporter) was found to be unique for a seagrass. Ion transport across the tonoplast of aquatic plants is poorly studied, with only two transporters described to date (an aquaporin and the SV channel). A molecular characterisation of the ion transporters of the aquatic plants is almost absent.