Excretion of riboflavin by iron deficient plants

Abstract

Roots of mild iron deficient plants have frequently been observed to excrete riboflavin. There is some evidence that the riboflavin contributes to iron efficiency.

Previous papers of this symposium have described several iron response mechanisms. Another possible iron stress response is that of excretion of riboflavin which has been demonstrated with iron deficiency in many plant species (Frolich and Wallace, 1966; Nagarajah and Ulrich, 1966; Wallace et al., 1968, 1971a,b; and Welkie and Miller, 1960). After a short period of iron deficiency, roots of tobacco, soybeans, sugar beets. Ambrosia, and others excrete riboflavin. Enhanced iron transport in the xylem exudate of tobacco under iron deficiency was associated with riboflavin in the exudate (Wallace, 1971a). The same workers found improved greening of iron deficient tobacco plants after the riboflavin color had disappeared from the nutrient solution (Wallace, 1969). The role of riboflavin has never been fully evaluated even though riboflavin production has been frequently observed as an iron stress response mechanism.

Key words:

• Iron deficiency
• riboflavin