LIGHT-INDUCED CIRCADIAN-RHYTHMS IN NADP+-GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE MESSENGER-RNA IN CORN SEEDLINGS

Chloroplast GAPDH (NADP+-glyceraldehyde-3-phosphate dehydrogenase) (EC 1.2.1.13) is one of the photosynthetic enzymes which make up the set of reactions responsible for carbon fixation in plants. We here report that fully expanded green corn leaves showed diurnal variations in GAPDH mRNA level as well as enzyme activity in response to light:dark cycles. In continuous bright light the mRNA, but not the enzyme activity rhythm persisted. This is the first time a circadian rhythm in GAPDH mRNA level is reported; the existence of light-driven rhythms in higher plants is thus further established.