African Journal of
Biotechnology

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12145

Full Length Research Paper

Growth and nitrogen metabolism changes in NaCl-stressed tobacco (Nicotiana rustica L. var. Souffi) seedlings

Chokri Zaghdoud1*, Houda Maâroufi-Dguimi2, Youssef Ouni3, Mokhtar Guerfel4, Houda Gouia2, Kamel-Eddine Negaz1, Ali Ferchichi1 and Mohamed Debouba4
  1Laboratoire d'Aridoculture et Cultures Oasiennes. Institut des Régions Arides (IRA), Université de Gabès, Médenine 4119, Tunisia. 2Unité de recherche Nutrition et Métabolisme Azotés et Protéines de Stress 99/UR/C 09-20, Faculté des Sciences de Tunis, Université de Tunis el Manar, 1060 Tunis, Tunisie. 3Laboratory of Extremophile Plants, Biotechnology Centre of Borj-Cedria, University of Tunis El Manar, P.O. Box 901, Hammam-Lif 2050, Tunisia. 4Institut Supérieur de Biologie Appliquée de Médenine, route El Jorf - Km 22.5, 4119 Médenine, Université de Gabès, Tunisia.
Email: [email protected]

  •  Accepted: 05 December 2012
  •  Published: 31 March 2013

Abstract

 

While salinity effects have been largely documented in crop plants, little data are available on Nicotiana rustica species (snuff tobacco), mainly nitrogen metabolism changes. Here, tobacco (N. rustica L. var. Souffi) seedlings were grown for one month on control medium, and then exposed for seven days to different levels of salt stress (0, 50, 100 and 200 mM NaCl). A significant decrease in dry weight accumulation was observed only at 200 mM NaCl. Na+ and Cl- ions accumulation was greater in leaves relative to roots, while growth was similarly decreased in both organs. Referring to roots, leaf water content was less affected by salinity. The increase of endogenous levels of salt ions was accompanied by a drop in NO3-content in both leaves and roots, and a more pronounced decrease in K+ content in leaves. Under salinity, nitrate reductase activity (NR, EC 1.6.1.6) was inhibited in both leaves and roots. The activities of nitrite reductase (NiR, EC 1.7.7.1) and glutamine synthetase (GS, EC 6.3.1.2) were inhibited in leaves but not in roots by salt stress. In stressed seedlings, NH4+ contents, protease activity, aminating and deaminating activities of glutamate dehydrogenase (NADH-GDH and NAD-GDH, EC 1.4.1.2) were enhanced mainly in the leaves. It could be stated that tobacco leaves and roots exhibited similar salt sensitivity in terms of growth and NO3- assimilation (NR activity), however they showed differential response for salt ions accumulation and NH4+metabolism steps (GS and GDH).

 

Key words: Assimilation, growth, salt stress, nitrogen, mineral nutrition, tobacco.

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