Effect of non-metabolic conditions on the uptake of aluminum by plant roots

Abstract

The mechanism of A1 uptake by plant roots in relation to non-metabolic conditions was investigated. Under normal conditions A1 is absorbed in an exchangeable manner at almost all the Ca existing sites on the cell walls of roots. Various kinds of metabolic inhibitors, especially chloroform gas and DNP, increased the A1 uptake by roots significantly. N4 gas treatment injured irreversibly the membranes of the cells of the cortex and the endodermis which are regarded as the barrier to the passive movement of Al, and consequently A1 uptake by roots increased appreciably. Resistance of cell membranes to the N2 gas treatment was in the order of cucumber, bottle gourd, rice, asparagus ≫ pea, Japanese radish > barley, edible burdock, spinach. This order was similar to that of Al tolerance among plant species. From these results, it was demonstrated that the maintenance of the normal physiological function of roots and the improvement of root environment are essential to minimize Al toxicity.