Influence of NaCl Stress on NH_4~+ Assimilation and Activity of Glutamine Synthetase of Two Mulberry Species

The effects of exogenous NaCl stress on the enzymes related to nitrogen metabolism and ammonium accumulations were studied in two mulberry species seedlings (Shinichinose and Yu151)cultivated in sands by shoot cuttage.The results showed that NaCl stress obviously inhibited the vegetative growth of two mulberry species,led to NH + 4 accumulation in mulberry leaves,while little changes in roots,and resulted in decreases in activities of glutamine synthetase both in leaves and roots,obvious increases in activities of glutamate dehydrogenase in leaves.The activity of nitrate reductase extracted from roots was stimulated at any rates under NaCl stress,while that in leaves was apparently declined.The consequences suggested that NaCl stress could affect the nitrogen metabolism of mulberry in salinity through weakening NH + 4 assimilation via the glutamine synthetase glutamate synthase cycle,enhancing the pathway of glutamate dehydrogenase,and influencing NO - 3 reduction.