Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette Cedex, France.
Photosynth Res. 2020 Apr;144(1):63-72. doi: 10.1007/s11120-020-00733-y. Epub 2020 Mar 18.
In photosynthesis research, non-invasive in vivo spectroscopic analyses have been used as a practical tool for studying photosynthetic electron transport. Klas-NIR spectrophotometer has been recently developed by Klughammer and Schreiber (Photosynth Res 128:195-214, 2016) for in vivo measurements of redox changes of P700, plastocyanin (Pcy) and ferredoxin (Fd). Here we show examples using the Klas-NIR spectrophotometer for the evaluation of the redox states and quantities of these components in plant leaves and cyanobacterial suspensions. The redox poise under light of the electron transport components is different in leaves from higher plants compared with cyanobacteria. During a short illumination with an actinic light, P700, Pcy, and Fd are kept reduced in barley leaves but are oxidized in cyanobacteria. During far-red light illumination, P700 and Pcy are mostly oxidized in the leaves but are partially kept reduced in cyanobacteria. In the cyanobacterium, Thermosynechococcus elongatus, which has no Pcy but uses cytochrome c (cyt c) as the electron donor to photosystem I, a cyt c signal was detected in vivo. To show the potential of Klas-NIR spectrophotometer for studying different developmental stages of a leaf, we performed measurements on fully mature and early senescing barley leaves. Pcy content in leaves decreased during senescence at an early stage. The Pcy loss was quantitatively analyzed using Klas-NIR spectrophotometer, giving absolute ratios of Pcy to PSI of 2.5 and 1.6 in younger and older leaves, respectively. For quantification of the signals in vivo, in vitro data (Sétif et al. in Photosynth Res142:307-319, 2019) obtained with Klas-NIR spectrophotometer were used.
在光合作用研究中，非侵入性的体内光谱分析已被用作研究光合作用电子传递的实用工具。Klas-NIR 分光光度计是由 Klughammer 和 Schreiber（Photosynth Res 128:195-214, 2016）最近开发的，用于活体测量 P700、质体蓝素（Pcy）和铁氧还蛋白（Fd）的氧化还原变化。在这里，我们展示了使用 Klas-NIR 分光光度计评估植物叶片和蓝细菌悬浮液中这些成分的氧化还原状态和数量的实例。与蓝细菌相比，高等植物叶片中电子传递成分的氧化还原平衡点在光照下有所不同。在短暂的强光照射下，P700、Pcy 和 Fd 在大麦叶片中保持还原状态，但在蓝细菌中被氧化。在远红光照射下，P700 和 Pcy 在叶片中大部分被氧化，但在蓝细菌中部分保持还原。在没有 Pcy 但使用细胞色素 c（cyt c）作为电子供体给光系统 I 的蓝细菌 Thermosynechococcus elongatus 中，体内检测到 cyt c 信号。为了展示 Klas-NIR 分光光度计在研究叶片不同发育阶段的潜力，我们对完全成熟和早期衰老的大麦叶片进行了测量。在衰老的早期，叶片中 Pcy 的含量下降。使用 Klas-NIR 分光光度计对 Pcy 的损失进行了定量分析，在较年轻和较老的叶片中分别给出了 Pcy 与 PSI 的绝对比值为 2.5 和 1.6。为了对体内信号进行定量分析，使用了 Klas-NIR 分光光度计获得的体外数据（Sétif 等人，Photosynth Res142:307-319, 2019）。
