Studies on photosynthetic electron transport,photophosphorylation and CO2 fixation in zinc deficient leaf cells of Zea mavs. L. |
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Authors: | CK Shrotri VS Rathore P Mohanty |
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Institution: | 1. Department of Biological Sciences , G.B. Pant University of Agriculture &2. Technology , Pantnagar, U.P., 263 145, India;3. School of Life Sciences , Jawharlal Nehru University , New Delhi, 110 067, India |
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Abstract: | The effect of Zn deficiency on rate of photosynthesis of leaf discs, isolated mesophyll and bundle sheath cells and chloroplasts of maize (Zea mays. L) was studied. The yield of mesophyll and bundle sheath cells obtained by enzymic digestion of the leaf tissues from Zn deficient plants is lower than the identical tissues from normal plants which suggests that Zn deficiency brings about some structural changes in the leaf cell. Photosynthetic oxygen evolution measured in the leaf discs is low due to Zn deficiency. Photosystem‐II dependent Hill reaction and non cyclic photophosphorylation of chloroplasts were also affected by Zn deficiency. Rate of photosynthetic carbon dioxide fixation by both bundle sheath and mesophyll cells obtained from Zn deficient leaf‐tissue waslower than the cells free from Zn deficiency. Addition of various metabolites like NADPH, ATP and PEP to Zn deficient mesophyll cells whowed marked enhancement in 14‐CO2 fixation. However, addition of NADPH, ATP and RuBP to Zn deficient bundle sheath cells showed no or very little enhancement in the rate of 14‐Cu2 fixation. Addition of exogenous Zn ions to isolated cells inhibited the CO2 fixation both in the non‐deficient and Zn deficient cell types. It is suggested that Zn deficie ‐ncy affects the primary electron transport and phospho‐rvlation ability for chloroplasts which in turn affects CO2 fixation in leaf cells. |
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Keywords: | Zn‐deficiency photosynthesis electron transport photophosphorylation |
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