Kou, JiancunTakahashi, ShunichiOguchi, RiichiBadger, MurrayChow, Wah SoonKuang, T.Lu, C.Zhang, L.2014-05-052014-05-05August 22-Kou, J., Takahashi, S., Oguchi, R., Badger, M. R., Chow, W. S. (2012). Quantification of cyclic electron flow in spinach leaf discs. In T. Kuang, C. Lu, L. Zhang (Eds), Photosynthesis research for food, fuel and future: 15th International Congress on Photosynthesis (pp. 271-274). Beijing: The Institute of Botany, Chinese Academy of Sciences and International Society of Photosynthesis Research978-7-308-09694-2973-3-642-32033-0978-3-642-32034-7http://hdl.handle.net/1885/11611We quantified the photosynthetic cyclic electron flux (CEF) around Photosystem I as the difference between the total electron flux through PS I (ETR1) and the linear electron flux through both photosystems. Both measurements were made in the whole tissue of spinach leaf discs illuminated in the same geometry and in CO2-enriched air to suppress photorespiration. (1) CEF was negligibly small below 300 μmol photons m-2 s-1. Above this irradiance, CEF increased approximately linearly up to the highest irradiance used (1900 μmol photons m-2 s-1). (2) CEF at a fixed irradiance of 980 μmol m-2 s-1 increased by a factor of almost 3 as the temperature was increased from 5°C to 40°C. It did not decline, even when the linear electron flux decreased at high temperatures. (3) Antimycin A, at a high concentration, decreased CEF to about 10% of the control value without affecting the linear electron flux. This method appears to be reliable for quantifyin! g CEF non-intrusively. By contrast, estimation of the linear electron flux from chlorophyll fluorescence over-estimated CEF in the above treatments.A China Scholarship Council fellowship to (JK) and grants from the Australian Research Council to WSC (DP1093827)and MRB (Centre of Excellence in Plant Energy Biology)supported this work.4 pages© Zhejiang University Press, Hangzhou and Springer - Verlag GmbHAntimycin AcyclicelectronflowlinearP700Photosystem I2012-07-012021-08-01