Response of Calmodulin-Dependent and Calmodulin-Independent NAD Kinase to Aluminium in Root Tips from Various Cultivated Plants

Abstract

The activity of NAD kinase (E.C. 2.7.1.23.) was studied in root apical meristems of various crops as well as aneuploid lines of Chinese Spring wheat cultivar growing for 4d in nutrient solution with or without alluminium. The level of aluminium tolerance in cereals (rye, wheat, barley and oat) corresponds to the level of total NAD kinase activity. In the most tolerant oat this activity is five times higher than in Al sensitive barley. Al stress causes a three-fold increase of the total NAD kinase activity in oat and two-fold in other cereals. Under these conditions calmodulin-dependent activity increases in sensitive genotypes, while it decreases in Al tolerant ones. In the two legume cultivars studied (lupine and pea) the response of total activity is exactly the reverse of that in cereals; however, the calmodulin-dependent activity follows the same course of reaction as in cereals. In Chinese Spring wheat cultivar the factors responsible for extinguishing the increase of calmodulindependent NAD kinase activity are located on the long arms of chromosomes 4D and 2D, whereas the genes located on the short arm of chromosome 5A control other mechanisms of Al tolerance.