The development of photophosphorylation and photosynthesis in greening bean leaves

Abstract

Photophosphorylation and oxygen evolution were measured in 8-day-old dark-grown bean leaves (Phaseolus vulgaris) after various times of greening in far red light and in white light. The sequence of development was the same for both greening regimes, but the processes were much more rapid in white light. The capacity for photophosphorylation, as assayed by the firefly luciferase assay, appeared after 12 hours in far red light. At this stage and for times up to 24 hours, photophosphorylation was not inhibited by 10(-5)m 3-(3,4-dichlorophenyl)-1,1-dimethylurea. At 24 hours, the capacity for oxygen evolution appeared and photophosphorylation became partially inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethylurea at concentrations which inhibited oxygen evolution. In white light photophosphorylation appeared after 15 minutes, and oxygen evolution at one hour. Photophosphorylation became partially sensitive to 3-(3,4-dichlorophenyl)-1,1-dimethylurea when oxygen evolution appeared. Carbonylcyanide m-chlorophenyl-hydrazone inhibited photophosphorylation and photosynthesis at low concentrations, 10(-5)m, with immature leaves, but the leaves developed resistance to carbonylcyanide m-chlorophenyl-hydrazone as they greened.