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Plant Physiology 60:640-644 (1977) © 1977 American Society of Plant Biologists Development of Photosystem I and Photosystem II Activities in Leaves of Light-grown Maize (Zea mays) 1a Department of Biology, University of York, Heslington, York Y01 5DD, United Kingdom
To compare chloroplast development in a normally grown plant with etiochloroplast development, green maize plants (Zea mays), grown under a diurnal light regime (16-hour day) were harvested 7 days after sowing and chloroplast biogenesis within the leaf tissue was examined. Determination of total chlorophyll content, ratio of chlorophyll a to chlorophyll b, and O2-evolving capacity were made for intact leaf tissue. Plastids at different stages of development were isolated and the electron-transporting capacities of photosystem I and photosystem II measured. Light saturation curves were produced for O2-evolving capacity of intact leaf tissue and for photosystem I and photosystem II activities of isolated plastids. Structural studies were also made on the developing plastids. The results indicate that the light-harvesting apparatus becomes increasingly efficient during plastid development due to an increase in the photosynthetic unit size. Photosystem I development is completed before that of photosystem II. Increases in O2-evolving capacity during plastid development can be correlated with increased thylakoid fusion. The pattern of photosynthetic membrane development in the light-grown maize plastids is similar to that found in greening etiochloroplasts.
2 Present address: Department of Biology, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom. 1 This work was supported by a Grant (GRA 38298) to R. M. L. from the Science Research Council. This article has been cited by other articles:
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