Metabolite pools and carbon flow during C4 photosynthesis in maize: 13CO2 labeling kinetics and cell type fractionation.
Metabolite pools and carbon flow during C4 photosynthesis in maize: 13CO2 labeling kinetics and cell type fractionation.
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DOI：
10.1093/jxb/erw414
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发表时间：
2017-01
影响因子：
6.9
通讯作者：
Stitt M
中科院分区：
文献类型：
--
作者：
Arrivault S;Obata T;Szecówka M;Mengin V;Guenther M;Hoehne M;Fernie AR;Stitt M
对代谢物的标记动力学、池大小和浓度梯度的分析揭示了玉米在Calvin-Benson循环和CO2浓缩穿梭之间的多条脱羧基途径的操作和碳的快速移动。世界范围内将C4光合作用转化为C3作物的努力需要深入了解这一复杂的途径是如何运作的。二氧化碳被结合到叶肉中的四碳代谢物中，这些代谢物移动到维管束鞘中，在那里它们被脱羧化，使二氧化碳集中在Rubisco周围。我们在玉米上进行了13CO2的动态标记，以分析C4光合作用中的碳流。总的标记动力学反映了C4光合作用的拓扑结构。对分离后的细胞特异性标记模式的分析表明，在主要的二氧化碳浓缩穿梭中，浓度梯度驱动苹果酸而不是丙酮酸在细胞间扩散。他们还揭示了天冬氨酸、丙氨酸和丙酮酸的胞间浓度梯度，以驱动第二个磷酸烯醇式丙酮酸羧激酶(PEPCK)类型的穿梭，该穿梭将10-14%的碳携带到束鞘中。3-磷酸甘油酸和磷酸三糖的细胞间交换也存在梯度。在卡尔文-本森循环和二氧化碳浓缩航天飞机之间有快速的碳交换，相当于碳增量的10%。相比之下，从碳浓度中的大量代谢物中泄漏出来的碳很少，进入呼吸代谢。我们推测，多个航天飞机的存在，以及它们之间的碳转移和卡尔文-本森循环，赋予了C4光合作用极大的灵活性。
Analysis of labeling kinetics, pool sizes, and concentration gradients of metabolites reveals the operation of multiple decarboxylation pathways and rapid movement of carbon between the Calvin–Benson cycle and the CO2-concentrating shuttles in maize. Worldwide efforts to engineer C4 photosynthesis into C3 crops require a deep understanding of how this complex pathway operates. CO2 is incorporated into four-carbon metabolites in the mesophyll, which move to the bundle sheath where they are decarboxylated to concentrate CO2 around RuBisCO. We performed dynamic 13CO2 labeling in maize to analyze C flow in C4 photosynthesis. The overall labeling kinetics reflected the topology of C4 photosynthesis. Analyses of cell-specific labeling patterns after fractionation to enrich bundle sheath and mesophyll cells revealed concentration gradients to drive intercellular diffusion of malate, but not pyruvate, in the major CO2-concentrating shuttle. They also revealed intercellular concentration gradients of aspartate, alanine, and phosphenolpyruvate to drive a second phosphoenolpyruvate carboxykinase (PEPCK)-type shuttle, which carries 10–14% of the carbon into the bundle sheath. Gradients also exist to drive intercellular exchange of 3-phosphoglycerate and triose-phosphate. There is rapid carbon exchange between the Calvin–Benson cycle and the CO2-concentrating shuttle, equivalent to ~10% of carbon gain. In contrast, very little C leaks from the large pools of metabolites in the C concentration shuttle into respiratory metabolism. We postulate that the presence of multiple shuttles, alongside carbon transfer between them and the Calvin–Benson cycle, confers great flexibility in C4 photosynthesis.
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影响因子：
4.9
作者：
Dong, LY;Masuda, T;Izui, K
通讯作者：
Izui, K
影响因子：
7.4
作者：
DAI, ZY;KU, MSB;EDWARDS, GE
通讯作者：
EDWARDS, GE
影响因子：
11.6
作者：
Gibon, Y;Blaesing, OE;Stitt, M
通讯作者：
Stitt, M
影响因子：
6.9
作者：
Braeutigam, Andrea;Schliesky, Simon;Weber, Andreas P. M.
通讯作者：
Weber, Andreas P. M.
DOI：
10.1016/0005-2728(83)90195-0
发表时间：
1983-01-01
期刊：
BIOCHIMICA ET BIOPHYSICA ACTA
影响因子：
--
作者：
FLUGGE, UI;GERBER, J;HELDT, HW
通讯作者：
HELDT, HW