RIBULOSE-1,5-BISPHOSPHATE CARBOXYLASE AND PHOSPHOENOLPYRUVATE CARBOXYLASE ACTIVITY IN BARLEY AND ITS VIRESCENS MUTANT

The most pronounced difference in carboxylase activities between Gateway barley and its virescens mutant occurred in seedlings grown in the light for 4 days. At this stage seedlings of Gateway had 11 times more ribulose-1,5-bisphosphate carboxylase and 18 times higher activity per gram fresh weight than the mutant. Although phosphoenolpyruvate carboxylase represented only 8% of the sum of the two carboxylase activities for the normal it accounted for 70% in the mutant. It represented 17% and 30% of the activity in 8-day dark-grown seedlings of the normal and mutant respectively but accounted for only 3% and 11% after 8 days in light. The high activity of phosphoenolpyruvate carboxylase in young seedlings of the mutant grown in light suggests an adaptation within the mutant during the period when the amount of RuBP-carboxylase is low. © 1979.