C₄ photosynthesis in C₃ rice: a theoretical analysis of biochemical and anatomical factors

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• 作者：Shuyue Wang ; Danny Tholen and Xin-Guang Zhu
• 刊名：Plant, Cell & Environment
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：40
• 期：1
• 页码：80-94
• 全文大小：1064K
• ISSN：1365-3040

文摘

Engineering C₄ photosynthesis into rice has been considered a promising strategy to increase photosynthesis and yield. A question that remains to be answered is whether expressing a C₄ metabolic cycle into a C₃ leaf structure and without removing the C₃ background metabolism improves photosynthetic efficiency. To explore this question, we developed a 3D reaction diffusion model of bundle-sheath and connected mesophyll cells in a C₃ rice leaf. Our results show that integrating a C₄ metabolic pathway into rice leaves with a C₃ metabolism and mesophyll structure may lead to an improved photosynthesis under current ambient CO₂ concentration. We analysed a number of physiological factors that influence the CO₂ uptake rate, which include the chloroplast surface area exposed to intercellular air space, bundle-sheath cell wall thickness, bundle-sheath chloroplast envelope permeability, Rubisco concentration and the energy partitioning between C₃ and C₄ cycles. Among these, partitioning of energy between C₃ and C₄ photosynthesis and the partitioning of Rubisco between mesophyll and bundle-sheath cells are decisive factors controlling photosynthetic efficiency in an engineered C₃–C₄ leaf. The implications of the results for the sequence of C₄ evolution are also discussed.