Wang Shuyue, Tholen Danny, Zhu Xin-Guang
Key Laboratory of Computational Biology, CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Plant Cell Environ. 2017 Jan;40(1):80-94. doi: 10.1111/pce.12834. Epub 2016 Oct 7.
Engineering C 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 C metabolic cycle into a C leaf structure and without removing the C 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 C rice leaf. Our results show that integrating a C metabolic pathway into rice leaves with a C metabolism and mesophyll structure may lead to an improved photosynthesis under current ambient CO concentration. We analysed a number of physiological factors that influence the CO 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 C and C cycles. Among these, partitioning of energy between C and C photosynthesis and the partitioning of Rubisco between mesophyll and bundle-sheath cells are decisive factors controlling photosynthetic efficiency in an engineered C -C leaf. The implications of the results for the sequence of C evolution are also discussed.
将C4光合作用引入水稻被认为是提高光合作用和产量的一种有前景的策略。一个有待回答的问题是，在不消除C3背景代谢的情况下，将C4代谢循环引入C3叶片结构是否能提高光合效率。为了探究这个问题，我们建立了一个C3水稻叶片中维管束鞘细胞和相连叶肉细胞的三维反应扩散模型。我们的结果表明，在当前环境CO₂浓度下，将C4代谢途径整合到具有C3代谢和叶肉结构的水稻叶片中可能会提高光合作用。我们分析了许多影响CO₂吸收速率的生理因素，包括暴露于细胞间隙的叶绿体表面积、维管束鞘细胞壁厚度、维管束鞘叶绿体包膜通透性、 Rubisco浓度以及C3和C4循环之间的能量分配。其中，C3和C4光合作用之间的能量分配以及Rubisco在叶肉细胞和维管束鞘细胞之间的分配是控制工程化C3-C4叶片光合效率的决定性因素。还讨论了这些结果对C4进化顺序的影响。
