Effect of glycinebetaine on chloroplast ultrastructure, chlorophyll and protein content, and RuBPCO activities in tomato grown under drought or salinity

The effect of foliar-applied glycinebetaine (GB) on chloroplast ultrastruct ure, the amount of chlorophyll and proteins and ribulose-1,5-bisphosphate c arboxylase/oxygenase (RuBPCO) activity in stressed tomato leaves were analy sed. Initial, and total activity and activation state state of RuBPCO were also measured. RuBPCO activities, chloroplast area, and the number of plast oglobuli remained unaffected, while the relative area of starch granules in creased in GB-treated, salt-stressed tomato leaflets. Under drought-stress, the relative area of plastoglobuli increased upon GB application. The prim ary effect of GB was,however, the increased protein and chlorophyll content .