Rubisco and Photosynthesis in Cereal Crops(Recent Topics of the Agricultunal Biological Science in Tohoku University)

概要

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Genetic modification to enhance Rubisco efficiency in cereal crops would have great agronomic importance as the prospects for enhancement of photosynthesis. There are substantial variations in the kinetic properties of Rubisco exist among higher plants. Since the difference in Rubisco specific activity reflects difference in the photosynthetic rate at atmospheric CO_2 levels, lower specific activity from rice provides the possibility to improve leaf photosynthesis by the introduction of a more efficient Rubisco into rice. An attempt to increase Rubisco content by overexpressing the rbcS gene shows increases in Rubisco content for a given leaf N content in rice. However, it leads to an unbalance between the in-vivo capacities of Rubisco and other photosynthetic limiting factors. To maintain this balance, the enhancement of cytochrome b6/f complex content may be required as a determinant for RuBP regeneration. Another approach to improving photosynthesis is to introduce C_4 characteristics into rice. An optimal protein allocation with a lower amount of Rubisco of a high Vmax/Km(CO_2) type as well as Kranz leaf anatomy is important for an improvement of photosynthesis.
東北大学の論文