Xylem sap sampling - new approaches to an old topic

Xylem transport has been studied for many years because of the dominant role that it plays in the flow of water through the plant and in nutrient delivery from the root to the shoot. In recent years, increasing awareness about the importance of chemical signals transported in the xylem in several stress responses has added a further dimension to these studies. As a consequence, it is vital to obtain information about the dynamics of the concentrations and fluxes of nutrients and signal molecules in the xylem. The development of methods to study the dynamics of transport with a resolution of minutes rather than days is crucial for understanding the basic mechanisms of nutrient relations both internally and in response to the environment.