Effect of 3 3 4 dichlorophenyl 1 1 dimethylurea on benzyladenine induced stimulation of chlorophyll formation in etiolated cucumber cucumis sativus cultivar aonagajibai cotyledons
Memoirs of the Faculty of Science Kyoto University Series of Biology 10(2): 115-126
3-(3,4-Dichlorophenyl)-1,1-dimethylurea (DCMU) depresses the rate of chlorophyll (Chl) formation during the steady-state phase under continuous illumination in excised etiolated cotyledons of cucumber (Cucumis sativus L. cv. Aonagajibai) preincubated in darkness with either benzyladenine (BA) or water. The inhibition appears at a light fluence rate higher than 14 .mu.mol m-2 s-1 and the extent of the inhibition increases with increasing fluence rate. Under 295 .mu.mol m-2 s-1, the extent of the inhibition is greater in cotyledons pretreated with BA for either a short (6 h) or a long (14 h) period compared to that in BA-untreated control; the extent of the stimulation by dark BA-pretreatment of the steady-state rate is greater under 295 .mu.mol m-1 s-2 than under a lower fluence rate (43 .mu.mol m-2 s-1). Photosynthesis may contribute to the increase in the steady-state rate to a greater extent in BA-pretreated cotyledons than that in water controls under a high light fluence. DCMU scarcely suppresses 5-aminolevulinic acid accumulation in the presence of levulinic acid in both BA-pretreated and untreated cotyledons.