Effect of abscisic acid on growth and certain osmoregulatory metabolites in the leaf callus of Gymnocarpos decandrum

Callus from the desert plant Gymnocarpos decandrum was developed and recult ured in a medium supplemented with Abscisic acid (ABA). Growth, osmotic pot ential, water content and some osmoregulatory metabolites were analyzed. Ad dition of ABA in the callus medium enhanced a callus growth without counter acting other growth regulators in the medium. Added ABA increased callus wa ter uptake, important in resing imposed stresses. The acid also enhanced os moregulation, regardless of callus water content, by accumulation of some m etabolites and not by nutrient elements. The latter were exhausted by incre ased callus growth activity. Apart of this, there was an increase in the am ino acids which reversed ABA inhibitory effect and a decrease in those whic h enhanced its effect; even some of them could not be detected with time of ABA application. The accumulation of proline was a function of ABA and not of water content, while the reverse was true for quaternary ammonium compo unds (QAC).