Isolation and preliminary characterization of ATPase from olive calli grown at different auxin/cytokinin ratio

ATPase activity was studied in calli from olive (Olea europaea L.) petioles cultured in media modified in their auxin/cytokinin ratio in order to indu ce different morphogenetic responses, Addition of 0.54 mu M alpha-naphthale neacetic acid (NAA) or 14 mu M zeatin (ZEA) did not induce any morphogenesi s in calli and proton pump activity in vivo was very low, while calli produ ced roots at 27 or 11 mu M NAA + 0.28 mu M ZEA and possessed clearly detect able proton pump activity, ATPase activity associated with microsomes isola ted by differential centrifugation from different callus cultures had the s ame pH optimum and similar sensitivity toward nitrate and azide, However, m icrosomes isolated fi om non-morphogenetic calli had higher specific ATPase activity which was very poorly (6 %) inhibited by vanadate. Also, the frac tionation of these microsomes on a continuous sucrose gradient showed two p eaks of ATPase activity, the more pronounced one co-purifying with the Golg i marker enzyme, Triton-stimulated UDPase activity, suggesting thus the pre sence of very high ATPase activity in Golgi secretory vesicles, On the cont rary, ATPase activity of microsomes from calli producing roots was more sen sitive to vanadate (30 - 40 % inhibition), Furthermore, the component of AT Pase activity attributable to Golgi secretory vesicles was less abundant.