SHORT-TERM SHIFTS IN NITROGEN-METABOLISM IN MULBERRY MORUS-ALBA UNDERSALT SHOCK

Important biochemical parameters of nitrogen metabolism were studied i n the leaves and roots of mulberry, Morus alba, subjected to NaCl sali nity. The total protein content of the shocked plants declined with a progressive increase in accumulation of free amino acids. Concurrently , the protease activity in the tissues was also increased. Nitrate red uctase (NR) activity declined under stress conditions. Ammonia was acc umulated significantly in the tissue under salt stress conditions. The enhanced activities of NADH- and NADPH-dependent glutamate dehydrogen ase (NADH- and NADPH-GDH) coupled with increased activities of asparta te aminotransferase (AAT) and alanine aminotransferase (AlAT) may be i nvolved in detoxifying the excess levels of ammonia (by assimilation) found under stress conditions. The increased activity of glutamine syn thetase (GS) during stress conditions paralleled the elevated levels o f glutamine in the tissue. The magnitude of these changes increases ov er time and with stress intensity.