Nitrogen Source Influences Root to Shoot Signaling Under Drought

Abstract

The translocation of chemical signals within plants is important for plant adaptation to stress, especially abiotic stresses such as drought. As soils become dry, root-sourced signals are transported via the xylem to leaves. Nitrate is thought to play a role in modifying root to shoot signaling under drought. We present new data on experiments that used nitrate and ammonium nutrition to modify xylem sap pH. The changes in xylem sap composition in maize grown under either nitrate or ammonium nutrition were comprehensively measured. Our analysis of these results suggests a new hypothesis in which many of the changes in xylem sap composition are due to charge balance needing to be achieved when different types of solutes are transported into the xylem. These results provide new insight into some of the factors that influence root to shoot signaling under drought.