Effect of iron deficiency on the chemical composition of the xylem sap of barley

Barley (Hordeum vulgare L.) plants were grown hydroponically, and the effec t of Fe deficiency on the concentration of essential metals, phytosideropho res (PS), organic acids, and amino acids, in the xylem sap was elucidated. The Fe-deficient plants exuded xylem sap at a rate about 2.4-fold lower tha n the Fe-sufficient plants. Under Fe deficiency, the concentration of Fe de creased compared with that of Fe-sufficient plants, while the concentration s of K, Ca, and Mg were not significantly different, and those of fin, Zn, and Cu increased by Fe deficiency. The concentration of PS in the xylem sap of the Fe-deficient plants was about 24-fold higher than that of the Fe-su fficient plants. The concentrations of citrate, malate, and succinate in th e xylem sap increased 7.3-fold, 2.0-fold, and 1.8-fold, respectively, with Fe deficiency compared to those of the Fe-sufficient plants. The xylem conc entration of total amino acids increased 1.4-fold by Fe deficiency.