Accumulation of membrane-bound polypeptides in roots of Al-sensitive and Al-resistant barley cultivars under Al, pH and metal stresses

Accumulation of five membrane-bound polypeptides in roots of Al-sensitive (Alfor) and Al-resistant (Bavaria) barley cultivars were observed under stress conditions induced by different aluminium (Al3+) concentrations, pH values of root medium, and some heavy metal (Cu2+, Cd2+, Co2+) treatments. Aluminium in concentrations ranging from 1 up to 150 micro M induced an increased accumulation of 24.5, 25.5, 25.0 and 26.5 kDa polypeptides in the Al-sensitive cultivar. These polypeptides accumulated already on the first day of Al treatment in Al-sensitive cultivar. The accumulation of these polypeptides was uniform without quantitative differences depending on Al dose. In Al-resistant barley the accumulation of 25.5 and 26.5 kDa polypeptides appeared on the fourth day after application of 10 micro M Al concentration while accumulation of 24.5 and 25.0 kDa polypeptides were not detected either at 10 or 150 micro M of Al. One polypeptide with molecular mass of 32 kDa was accumulated in both barley cultivars. The accumulation started at 10 micro M Al concentration on the fourth day of Al treatment without quantitative differences among the applied Al concentrations. Changes in pH values of root medium (pH 3.5-6.5) did not show any effect on the accumulation of the analysed polypeptides. However, differences were found between two barley cultivars during heavy metal treatment. Application of 10 micro M concentration of heavy metals (Cu, Cd, and Co) in the root medium of Al-sensitive cultivar Alfor resulted in accumulation of polypeptides with molecular mass of 24.5, 25.5, 25.0 and 26.5 kDa very similar to Al treatment. On the other hand, the metal stress did not induce accumulation of these polypeptides in roots of the Al-resistant cultivar Bavaria