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We have established schedules of expression during maize leaf development in light and darkness for the messenger RNAs (mRNAs) and polypeptides for ribulose 1,5-bisphosphate carboxylase (RuBPCase) subunits, phosphoenolpyruvate carboxylase (PEPCase), and the light-harvesting chlorophyll a/b-binding protein (LHCP). Levels of mRNAs were measured by hybridization with cloned probes, and proteins were measured by immunodetection on protein gel blots . The initial synthesis in leaves of all four mRNAs follows a lightindependent schedule; illumination influences only the level to which each mRNA accumulates. The synthesis of RuBPCase small and large subunits and of PEPCase polypeptides also follows a light-independent schedule which is modified quantitatively by light. However, the accumulation of LHCP polypeptides absolutely requires illumination. The accumulation of each protein closely follows the accumulation of its mRNA during growth in light. Higher ratios of PEPCase and RuBPCase protein to mRNA occur during dark growth .

Yellow leaves of chlorophyll‐deficient seedlings and white leaves of Carotenoid deficient seedlings contain no detectable light‐harvesting chlorophyll a/b binding proteins (LHCP). Chlorophyll‐deficient leaves contain plastids which are arrested in development prior to chloroplast formation [Mascia, P. N. and Robertson, D. S. (1978) Planta (Berl.) 143, 207–211] while carotenoid‐deficient leaves contain plastids which are arrested in development at a rudimentary stage [Bachmann, M. D., Robertson, D. S., Bowen, C. C., and Anderson, I. C. (1967) J. Ultrastruc. Res. 21, 41–60]. Chlorophyll‐deficient leaves have normal levels of nuclear‐encoded LHCP mRNA while carotenoid‐deficient leaves contain only trace amounts of LHCP mRNA. Similar results were obtained with carotenoid deficiences caused by nuclear gene mutations and by treatment with the herbicide norflurazon which blocks carotenoid biosynthesis. We conclude that events at early stages of plastid development influence the accumulation of a nuclear‐encoded mRNA.