Nitrogen source differently regulates barley (Hordeum vulgare) response to NaCl stress at seed germination and early seedling development stages

• Published in: Cereal research communications 2015-06, Vol.43 (2), p.225-235
• Main Authors: Ounissi, A, Manai, J, Rabhi, M, Gouia, H, Debouba, M
• Format: Article
• Language: English
• Subjects: Agriculture; ammonium compounds; Analysis; Barley; enzyme activity; Germination; glutamate dehydrogenase; glutamic acid; glutamine; grasses; Hordeum vulgare; Life Sciences; lipid peroxidation; malondialdehyde; nitrate reductase; nitrates; nitric oxide; nitrites; nitrogen; Nitrogen in the body; Physiological aspects; Physiology; Plant Breeding/Biotechnology; Plant Genetics and Genomics; Plant Physiology; salinity; salt stress; Salt stress (Botany); seed germination; Seedlings; seeds; sodium chloride
• ISSN: 0133-3720; 1788-9170
• DOI: 10.1556/CRC.2014.0039

Nitrogen (N) acts as nutrient and signaling molecule in plants all over their development stages. The involvement of various N forms in the regulation of seed germination response to salt stress was assessed in the present work. Nitrogen sources (NO, NO2−, NO3−, NH4+, glutamine and glutamate) were added at 1mMto the germination medium of barley (Hordeum vulgare, cv Ardhaoui) in combination or not with NaCl stress (14 g.L−1). The application of nitrogen monoxide (NO) alleviated by about 20% the NaCl-induced germination capacity decrease. However, the addition of ammonium ions (NH4+) and glutamic acid (Glu) accentuated the inhibitory effects of NaCl, decreasing germination capacity by about 50% compared to the control. The levels of malondialdehyde (MDA), which is an indicator of membrane lipid peroxidation by stresses, were increased by salinity in seeds treated with nitrite (NO2−), NO3−, Glu and Gln. In N-free medium, NaCl stress induced a severe nitrate reductase activity (NR, EC 1.6.1.6) inhibition. Such an effect was alleviated by the application of N treatments. Glutamate dehydrogenase (GDH, EC 1.4.1.2) aminating activity (NADH-GDH) of seedlings was inhibited by NaCl stress in the presence of NO, Glu and Gln. Conversely, there was stimulation by salt stress of NADH-GDH activity in seedlings treated with NaCl and NH4+. Deaminating GDH activity (NAD-GDH) was found to be enhanced by salt stress in NO2− and NO3− treatments. The differential effects of applied N forms on germination and early seedling development processes in this grass probably underlines different regulatory actions within N mobilization and assimilation.