Effect of salicylic acid on the synthesis of ribulose-1,5-bisphosphate carboxylase/oxygenase in barley leaves

Abstract

Hordeum vulgare L. (cv. Alfa) was grown for 7 days over a range of salicylic acid (SA) concentrations (100 μmol/L-1 mmol/L), and the effect on the level of ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) was examined. The treated plants showed a decrease in the level of total soluble protein, in particular in the level of RubisCO. In the presence of 1 mmol/L SA the level of total soluble protein on a fresh weight basis was about 68% of the control, whereas the level of RubisCO was about 50% that of control plants. The percentage of inhibition on the small subunit was higher, as a result of which the small/large subunit ratio was lower for the experimental variants. When 7-day-old barley seedlings were supplied with SA through the transpiration stream for 24 h no changes in the levels of total soluble protein and RubisCO were observed. The influence of SA on the synthesis of RubisCO was followed by in vivo labelling with a 14C-amino acid mixure (14C-AAM). Results demonstrated that SA inhibited both the synthesis of total soluble protein and, more pronounced, the synthesis of RubisCO.