84 



Walter Bonner and Rober Hill 



ing had a wide band with 707. transmission between 680 and 1000 ti^i 

 Figure 2 shows the development of a light-activated response 

 following chlorophyll formation in the mung bean leaves, a res- 

 ponse that corresponds to the oxidation of cytochrome f. 



Initial Response I Hour 



554-544 



Fig. 2 Development of the light activated cytochrome f oxidation 

 during greening of etiolated mung bean leaves. The times indi- 

 cated refer to the number of hours the leaves were exposed to 

 broad-band, low intensity red light. 



Light induced cytochrome f oxidation could be observed in a 

 relatively short time following initiation of chlorophyll form- 

 ation. Maximal response was obtained after three hours of 

 greening, at which time the leaves were very slightly tinged with 

 green. Further greeningof the leaves did not increase the extent 

 of the light induced cytochrome f oxidation, but did markedly in- 

 crease the rate of the response." A relatively high light inten- 

 sity was required for cytochrome f oxidation in these partially 

 greened leaves (Figure 3). "" 



