Total protein was extracted from transgenic and wild-type plants using extraction buffer [0.1 M HEPES/KOH pH 7.0, 20 mM 2-mercaptoethanol, 0.1 mg ml )1 PMSF, 0.1% w/v Triton X-100, 1 mM EDTA, 20% w/v glycerol and protease inhibitor cocktail (Sigma-Aldrich, http://www.sigmaaldrich.com/)]. An aliquot of total protein was precipitated using trichloroacetic acid and quantified by the Bradford method (Bradford, 1976) . Reaction products were resolved by 12% SDS-PAGE and visualized by Western blotting using c-myc antibody (9E10; Santa Cruz Biotechnology, http://www.scbt.com) and an ECL kit (GE Healthcare, http://www.gehealthcare.com).