Total protein of both untransformed and transgenic plants was obtained by centrifugation at 2000×g, and 5-fold concentration. Protein concentration was estimated by the procedure of Bradford (1976). Western blotting was carried out as described in Sambrook et al. (1995). Proteins were separated in sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE, 15% acrylamide), and transferred to a Polyvinylidene fluoride (PVDF) membrane (Amersham) using a semi-dry transfer apparatus (Bio-Rad). The membranes were blocked for 1 h at room temperature with 150 mM NaCl, 10 mM Tris/HCl pH 8.0, 0.1% Tween 20 and 1% Triton X-100, and 5% (w/v) skimmed milk.