Characterization of Plasma membrane of winter wheat (TritiCum aestivum L.) Seedlings and Changes in ATP hydrolysing activity under low temparature stress

Plasma membranes were isolated from young seedlings of cold hardened and non-hardened winter wheat using aqueous polymer two phase system consisting of dextran-polyethyleneglycol. Electron microscopic analysis and activities of various marker enzymes revealed that the upper phase was enriched in plasma membrane and free from contamination by other membranes. The fraction thus obtained possessed Mg ATP hydrolysing activity with an optimum pH 6.5 and the activity was stimulated by K⁺. The activity was highly sensitive to orthovanadate, diethylstilbesterol, dicyclohexylcarbodimide, insensitive to azide and nitrate. It was suggested that the ATP hydrolysis was catalysed by H⁺ ATPase. Mg ATP hydrolysing activity in cold hardened seedlings was 38% higher than that from non-hardened seedlings.