DIFFERENTIAL CADMIUM ACCUMULATION IN DURUM WHEAT: ROLE OF LOW MOLECULAR WEIGHT ORGANIC ACIDS

Pairs of isolines of durum wheat (Triticum turgidum var durum) differ in the amount of cadmium translocated to aboveground tissues; in the field, the high isolines have twice the cadmium in leaves and grain when compared to the low isolines. The hypothesis that differential cadmium translocation is associated with differential production of organic acids was tested by measuring cadmium in tissues, cadmium partitioning within the root, and organic acids in tissues and root exudates. When grown in soil, no differences between high and low isolines were found. When grown in hydroponics, no differences in one pair (W9261-BG) were found. In the other pair (W9260-BC), the low isoline had half the cadmium in its shoot, increased cadmium in the root symplast and increased concentrations of fumaric, malic, oxalic and succinic acids compared to the high isoline. This suggests that reduced translocation to aboveground tissues was associated with increased chelation of cadmium in the root

Production of Organic Acids and Adsorption of Cd on Roots of Durum Wheat (Triticum turgidum L. var. durum)

A number of isolines of durum wheat (Triticum turgidum var durum) differ in their translocation of Cd. In the field, the high isolines accumulate twice the Cd in leaves and grain when compared to the low isolines. The hypothesis that differential accumulation of Cd is associated with differential production of organic acids was tested by measuring Cd content in tissues, Cd partitioning within the root, and organic acids in tissues. In solution culture, the high and low isolines of W9261-BG did not differ in any of the variables measured. Within W9260-BC, the low isoline had half the Cd in its shoot, 30% more tightly-bound Cd in the root and higher concentrations of fumaric, malic, and succinic acids in the root compared to the high isoline. Differential Cd accumulation may be linked to differential adsorption and retention of Cd in the roots of the low Cd-accumulating isolines, possibly via chelation with organic acids