ATP Levels and Energy Requirements of Ion Transport in Cells of Slices of Greening Barley Leaves

Abstract

Leaf slices obtained from 6 days old etiolated barley seedlings at various time intervals during greening were kept for 1 h in experimental solutions under various conditions. Under N2 in the dark ATP levels are rather low and independent of the time of greening. Under N2 in the light ATP levels significantly increase from the low level during the first 4 h of greening and then remain constant. In air ATP levels are similar in the light and in the dark, and rather independent of the time of greening; they are similar to the levels obtained in light + N 2 after 4 h of greening or longer. These results are compared with earlier experiments on ion uptake and photosynthesis of greening barley leaves. Ion uptake rates appear to be highly correlated with ATP levels. In light + N2 changes of ATP levels, of 36 C1 − and 86 Rb + uptake and of photosynthetic O 2 evolution during greening have the same kinetics.