Aluminum toxicity and tolerance of wheat

To elucidate aluminum (Al) toxicity and Al-tolerant mechanism, the pattern of Al-accumulation in roots of wheat (Triticum aestivum L.), absorption of Al to cell walls and Al-induced secretion of organic acids from roots were compared in Al-tolerant cultivar, Atlas 66, and Al-sensitive cultivar, Scout 66, of wheat. After exposed the roots to Al solution, more inhibition of root elongation was found in Scout 66. Al was mainly accumulated in the terminal 0 to 5 cm of roots. Scout 66 accumulated more Al in root apices and cell wall separated from root apices after Al treatment. However, after Al treatment difference in Al absorption to the cell walls separated from root apices before Al treatment between the cultivars was not found. In other hand, Al-induced malate acid was found in root exudates of Atlas 66, while no organic acid was found in that of Scout 66. These results indicated that less Al was accumulated in the roots of Atlas 66 than that of Scout 66. This difference seems related to the Al-induced secretion of organic acids from roots, but not to the capacity of cell walls itself to Al-accumulation.