Zhang Meng-Meng, Fan Da-Yong, Sun Guang-Yu, Chow Wah Soon
College of Life Science, Northeast Forestry University, Harbin, Heilongjiang, 150040, China.
Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT 2601, Australia.
Funct Plant Biol. 2018 Oct;45(11):1138-1148. doi: 10.1071/FP18039.
The cyclic electron flux (CEF) around photosystem I (PSI) was discovered in isolated chloroplasts more than six decades ago, but its quantification has been hampered by the absence of net formation of a product or net consumption of a substrate. We estimated in vivo CEF in leaves as the difference (ΔFlux) between the total electron flux through PSI (ETR1) measured by a near infrared signal, and the linear electron flux through both photosystems by optimised measurement of chlorophyll a fluorescence (LEFfl). Chlorophyll fluorescence was excited by modulated green light from a light-emitting diode at an optimal average irradiance, and the fluorescence was detected at wavelengths >710nm. In this way, LEFfl matched the gross rate of oxygen evolution multiplied by 4 (LEFO2) in broad-spectrum white actinic irradiance up to half (spinach, poplar and rice) or one third (cotton) of full sunlight irradiance. This technique of estimating CEF can be applied to leaves attached to a plant.
六十多年前，在分离的叶绿体中发现了围绕光系统I（PSI）的循环电子流（CEF），但其定量一直受到缺乏产物净形成或底物净消耗的阻碍。我们将叶片中的体内CEF估计为通过近红外信号测量的通过PSI的总电子流（ETR1）与通过优化测量叶绿素a荧光的两个光系统的线性电子流（LEFfl）之间的差值（ΔFlux）。叶绿素荧光由发光二极管发出的调制绿光在最佳平均辐照度下激发，并在波长>710nm处检测荧光。通过这种方式，在高达全日照辐照度的一半（菠菜、杨树和水稻）或三分之一（棉花）的广谱白色光化辐照度下，LEFfl与氧气释放的总速率乘以4（LEFO2）相匹配。这种估计CEF的技术可应用于附着在植物上的叶片。
