NaCl induced changes of the H+-ATPase in root plasma membrane of two wheat cultivars

Plasma membrane (PM) vesicles were purified from two wheat (Tritium aestivum yiujian24 (Y-J24) and longchun20 (L-Ch20)) roots by discontinuous sucrose gradient centrifugation to study the regulatory mechanism of the H+-ATPase activities in response to NaCl treatment. Salt-stress reduced the PM H+-ATPase activity in YJ24 roots, but increased in L-Ch20 roots. Analysis of lipid peroxidation in the wheat root PM vesicles indicated that NaCl treatment induced a higher degree of oxidative damage on Y424 root PM, but did not affect lipid peroxidation of L-Ch20 root PM. Further studies showed that the PM protein thiol (P-SH) contents correlated with the changes of H+-ATPase activity in YJ24 and L-Ch20 root PM. Western blot analysis revealed a decrease in the amount of the PM H+-ATPase in Y424 roots exposed for 72 h to 100 mM NaCl, and an increase in L-Ch20 roots, respectively. Therefore, thiol oxidation and a decrease in the enzyme content might be responsible for the inhibition of the PM H+-ATPase activity in Y424 roots in response to salt-stress; the increased H+-ATPase activities in L-Ch20 root PM might be due to up-regulation of the expression of the PM HI-ATPase. (C) 2003 Elsevier Ireland Ltd. All rights reserved.