Carbon isotope discrimination as a diagnostic tool for C4 photosynthesis in C3-C4 intermediate species.
Carbon isotope discrimination as a diagnostic tool for C4 photosynthesis in C3-C4 intermediate species.
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DOI：
10.1093/jxb/erv555
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发表时间：
2016-05
影响因子：
6.9
通讯作者：
von Caemmerer S
中科院分区：
文献类型：
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作者：
Alonso-Cantabrana H;von Caemmerer S
结合气体交换和碳同位素鉴别测量和建模用于检测和估计C3-C4中间物种中C4循环的贡献。C3-C4中间物质中C4循环的存在和活性已证明难以分析，尤其是当这种活性低时。本研究提出了一种检测C4活性并估算其对中间植物光合作用的贡献的策略，通过将可调谐二极管激光吸收光谱（TDLAS）与气体交换系统耦合，同时测量低O2分压下CO2同化（A）和碳同位素辨别（Δ）的CO2响应。C3-C4光合作用和Δ的数学模型然后使用相同的一组常数同时拟合两种响应。该策略应用于中间种Flaveria floridana和F. brownii和F. pringlei和F.黄顶菊作为C3和C4对照。我们的研究结果支持F中存在功能性C4循环。floridana，可以固定12-21%的碳。In F. brownii，75-100%的碳是通过C4循环固定的，叶肉Rubisco对整个碳同化的贡献随着两种中间植物中CO2分压的增加而增加。结合气体交换和Δ测量和建模是C4光合作用的强大诊断工具。
Combined gas exchange and carbon isotope discrimination measurement and modeling is used to detect and estimate the contribution of the C4 cycle in the C3-C4 intermediate species. The presence and activity of the C4 cycle in C3-C4 intermediate species have proven difficult to analyze, especially when such activity is low. This study proposes a strategy to detect C4 activity and estimate its contribution to overall photosynthesis in intermediate plants, by using tunable diode laser absorption spectroscopy (TDLAS) coupled to gas exchange systems to simultaneously measure the CO2 responses of CO2 assimilation (A) and carbon isotope discrimination (Δ) under low O2 partial pressure. Mathematical models of C3-C4 photosynthesis and Δ are then fitted concurrently to both responses using the same set of constants. This strategy was applied to the intermediate species Flaveria floridana and F. brownii, and to F. pringlei and F. bidentis as C3 and C4 controls, respectively. Our results support the presence of a functional C4 cycle in F. floridana, that can fix 12–21% of carbon. In F. brownii, 75–100% of carbon is fixed via the C4 cycle, and the contribution of mesophyll Rubisco to overall carbon assimilation increases with CO2 partial pressure in both intermediate plants. Combined gas exchange and Δ measurement and modeling is a powerful diagnostic tool for C4 photosynthesis.