ALUMINUM EFFECTS ON PYRIDINE-NUCLEOTIDE REDOX STATE IN ROOTS OF SCOTSPINE

After prolonged (3-9 weeks) hydroponic treatment of Scots pine seedlin gs with different concentrations (0.5-4.0 mM) of Al (Al(NO3)3), the le vels of pyridine nucleotides were determined in root homogenates. Afte r 3 weeks of Al stress, a significant decrease of the anabolic reducti on charge (ARC: NADPH/(NADP+ + NADPH) and an increase of the redox sta tus (NAD(P)H/NAD(P)+), catabolic reduction charge (CRC: NADH/(NAD+ + N ADH)) and phosphorylation capacity expressed as NADP+/NAD+ ratio was f ound in the 4.0 mM Al treatment. After 6 weeks, Al at concentrations o f 10.5 and 1.0 mM induced an enhancement of the NADH level and a reduc tion of NADPH level, but the redox ratios were not changed significant ly. After 9 weeks treatment with Al concentrations ranging from 0.5 to 4.0 mM, decreases of the relative level of NADP+ NADPH and NADH and i ncreases of NAD+ were found. Consequently, the CRC, NAD(P)H/NAD(P)+ an d NADP+/NAD+ ratios reached a minimum and ARC a maximum as compared to previous measurements.