The role of chloroplastic NAD(P)H dehydrogenase in photoprotection

After a brief exposure to supra-saturating light, leaves of a tobacco trans formant, in which chloroplastic NAD(P)H dehydrogenase (NDH) Tvas defective, showed more severe photoinhibition than the wild-type, when judged by the parameter of chlorophyll fluorescence Fv/Fm, Repeated application of supra- saturating light eventually resulted in chlorosis in the NDH-defective muta nt, while the mild-type sustained less photodamage and was able to recover from it. The mechanism of the phenomena is discussed with respect to the po tential role of NDH in photosynthesis. (C) 1999 Federation of European Bioc hemical Societies.