Abstract:
Leaf mesophyll cells of Zinnia elegans cv Envy could be induced to be frans differentiated in to tracheary
elements by anxin and cytokmin in cell suspension culture) with peak differentiation at 96 hours, which has
been used as a model system in studying the physiology and biochemistry of cellular differentiation. In the
present study, the involvement of calcium ions and calmodulin (CaM) in the process of tracheary element
(TE) differentiation was examined. Calcium chelator EGTA was used to deplete the Ca2+ concentration in
the medium while calmodulin inhibitors triffluoferazsn (TFP) and chlorpromazine (CPZ) were used to
inhibit the calmodulin activity. Blocking the Ca2+ sequestration with 0.1 mM EGTA and the inhibition of
calmodulin action by TFP and CPZ at 10 and 20 pM concentrations significantly inhibited the TE
differentiation process. It implies that, Ca2+ itself and Ca/CaM complex has a specific role to play in the
trans-differentiation process of Zinnia mesophyl! cells in to tracheary elements. Further increase in EGTA
upto O.SmM, TFP and CPZ upto 40 juM concentrations resulted a high rate of ceil death probably due to
non-specific toxic effects, which may lead to membrane damage.
