Salinity affects indirectly nitrate acquisition associated with glutamine accumulation in cowpea roots

Abstract

The aim of this study was to test the hypothesis that salinity can affect indirectly the nitrate acquisition by a negative modulation triggered by glutamine accumulation. Cowpea plants were exposed to a mild NaCl concentration (50 mM) in order to restrict growth and N-demand. After 21 d, pretreated plants and control plants were supplied with 0, 5 and 10 mM of Ca(NO3)2 for 3 d in absence of NaCl. Salt pretreated plants showed a great limitation in acquisition of NO3 -, indicated by decline in the nitrate uptake rate, NO3 - accumulation, nitrate reductase activity and protein content. The restriction of NO3 - utilization was positively associated with increased glutamine synthetase activity and glutamine accumulation, especially in roots.

Keywords

• glutamine synthetase
• nacl stress
• nitrate reductase
• nitrate uptake
• vigna unguiculata