biologia plantarum

Biologia plantarum 43:61-66, 2000 | DOI: 10.1023/A:1026550929375

NaCl Effects on Root Plasma Membrane ATPase of Salt Tolerant Wheat

M.M.F. Mansour¹, P.R. Van Hasselt², P.J.C. Kuiper²

¹ Department of Botany, Faculty of Science, Ain Shams University, Cairo, Egypt

² Department of Plant Biology, University of Groningen, Haren, The Netherlands

Wheat seedlings of a salt tolerant cultivar were grown hydroponically in presence and absence of 100 mM NaCl. Roots were harvested, and the plasma membrane (PM) fraction was purified. PM ATPase required a divalent cations for activity (Mg > Mn > Ca > Co > Zn > Ni > Cu), and it was further stimulated by monovalent cations (K > Rb > NH₄ > Li > choline > Cs). The pH optima were 6.0 and 5.6 in absence and presence of 25 mM KCl, respectively. The enzyme was sensitive to vanadate and DCCD but insensitive to azide, oligomycine and nitrate. The enzyme displayed a high preference for ATP but was also able to hydrolyze other nucleotide tri- and diphosphates. The enzyme activity showed a simple Michaelis-Menten kinetics for the substrate Mg²⁺-ATP in both control and salt exposed roots. The polypeptide patterns of control and salt stressed PM fractions, detected by SDS-PAGE, were very similar. NaCl substantially reduced the PM ATPase specific activity, whereas it had little effect on the apparent K_m for Mg²⁺-ATP. Since the root PM ATPase of salt sensitive and resistant genotypes responded similarly to salinity stress, it seems unlikely that the mechanism of salt tolerance in wheat is primarily based on differences in PM ATPase characteristics.

Keywords: lipids; polypeptide pattern; salt stress; Triticum aestivum

Subjects: genotype differences, salt tolerance, ATPase; lipids, salt tolerance, ATPase; NaCl stress, root plasma membrane ATPase; polypeptide pattern, salt tolerance, ATPase; root plasma membrane ATPase; salinity, root plasma membrane ATPase; Triticum aestivum; wheat, salt tolerance, ATPase

Published: March 1, 2000  Show citation