A comparison based on delayed light emission and fluorescence induction of intact chloroplasts isolated from mesophyll protoplasts and bundle-sheath cells of maize.

Chloroplasts or cells from maize (Zea mays) bundle sheath show a very low intensity of delayed light emission compared with mesophyll protoplasts or chloroplasts. The bundle-sheath chloroplasts retain only the fast (less than 1 ms) component of the emission. They also fail to show fluorescence induction in contrast to the mesophyll, which behaved normally. The mesophyll material could be made to resemble the bundle-sheath chloroplasts in respect of both phenomena by adding to it 1-(3',4'-dichlorophenyl)-3,3-dimethyl-urea and hydroxylamine, together. It is concluded that Photosystem II, that gives rise to both effects, is not active in the bundle sheath but may be present in an inhibited form.