1. Diversity in photosynthetic electron transport under [CO 2 ]-limitation: the cyanobacterium Synechococcus sp. PCC 7002 and green alga Chlamydomonas reinhardtii drive an O 2 -dependent alternative electron flow and non-photochemical quenching of chlorophyll fluorescence during CO 2 -limited photosynthesis / Photosynth Res / Ginga Shimakawa, Seiji Akimoto, Yoshifumi Ueno, Ayumi Wada, Keiichiro Shaku, Yuichiro Takahashi, and Chikahiro Miyake / Ginga Shimakawa; Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan; e-mail: gshimakawa@stu.kobe-u.ac.jp.

2. Supplemental Fig. S1. Dependence of Y(II) on [O 2 ] during CO 2 -limited photosynthesis in ambient [CO 2 ] grown S. 6803 and S. 7942. Blue symbols and black symbols represent Y(II) in S. 6803 and S. 7942, respectively. Measurements were performed three times indicated by circles, triangles, and squares respectively. For the measurements, -glucose (5 mM), catalase (250 units mL −1 ), and glucose oxidase (5 units mL −1 ) were added to the reaction mixture containing 50 mM HEPES (pH 7.5) and 10 µg Chl mL −1 cells at 25˚C. Cells were illuminated with red actinic light (AL; 150 µmol photons m −2 s −1 ). Diversity in photosynthetic electron transport under [CO 2 ]-limitation: the cyanobacterium Synechococcus sp. PCC 7002 and green alga Chlamydomonas reinhardtii drive an O 2 -dependent alternative electron flow and non-photochemical quenching of chlorophyll fluorescence during CO 2 -limited photosynthesis / Photosynth Res / Ginga Shimakawa, Seiji Akimoto, Yoshifumi Ueno, Ayumi Wada, Keiichiro Shaku, Yuichiro Takahashi, and Chikahiro Miyake / Ginga Shimakawa; Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan; e-mail: gshimakawa@stu.kobe-u.ac.jp.

3. Supplemental Fig. S2. Responses of Y(I) and Y(II) to CO 2 -limitation in ambient [CO 2 ] grown S. 7002. Measurements on medium with cyanobacteria (10 μg Chl mL −1 ) started by illumination with red actinic light (AL; 150 μmol photons m −2 s −1 ). The red line shows relative Chl fluorescence yields. Blue diamonds and white circles respectively show Y(I) and Y(II). Glucose (5 mM) and catalase (250 units mL −1 ) were added at the points indicated as black arrow, and glucose oxidase (5 units mL −1 ) was added as red one. Measurements were performed three times, and the representative data was shown. Diversity in photosynthetic electron transport under [CO 2 ]-limitation: the cyanobacterium Synechococcus sp. PCC 7002 and green alga Chlamydomonas reinhardtii drive an O 2 -dependent alternative electron flow and non-photochemical quenching of chlorophyll fluorescence during CO 2 -limited photosynthesis / Photosynth Res / Ginga Shimakawa, Seiji Akimoto, Yoshifumi Ueno, Ayumi Wada, Keiichiro Shaku, Yuichiro Takahashi, and Chikahiro Miyake / Ginga Shimakawa; Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan; e-mail: gshimakawa@stu.kobe-u.ac.jp.

4. Supplemental Fig. S3. The effect of white light on [O 2 ] (red) and relative Chl fluorescence (black) in ambient [CO 2 ] grown S. 7002. Initially media containing the cells (10 μg Chl mL −1 ) were kept dark; illumination with measuring light (ML) and white actinic light (AL; 140 μmol photons m −2 s −1 ) started as indicated. The downward shift in the Chl fluorescence signal (F o ) after the start of ML illumination is due to increasing the instrument amplification from 200 to 100 mV. Chl fluorescence parameters have the usual definitions (see the legend of Fig. 1). NaHCO 3 (final concentration 10 mM) was added as indicated. Indicated α, β, and γ denote times at which O 2 evolution rates were determined. Blue shadings indicate that the oxygen electrode chamber was closed, the O 2 signal amplitude was doubled, and measurement time scale was reduced to 1/10. Measurements were performed three times and representative data are shown. O 2 evolution rates were −15 ± 6, 50 ± 4, 16 ± 8, 55 ± 8 respectively at dark, α, β, and γ. Y(II) were 0.28 ± 0.01, 0.26 ± 0.01, 0.30 ± 0.02 respectively at α, β, and γ (mean ± SD). Diversity in photosynthetic electron transport under [CO 2 ]-limitation: the cyanobacterium Synechococcus sp. PCC 7002 and green alga Chlamydomonas reinhardtii drive an O 2 -dependent alternative electron flow and non-photochemical quenching of chlorophyll fluorescence during CO 2 -limited photosynthesis / Photosynth Res / Ginga Shimakawa, Seiji Akimoto, Yoshifumi Ueno, Ayumi Wada, Keiichiro Shaku, Yuichiro Takahashi, and Chikahiro Miyake / Ginga Shimakawa; Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan; e-mail: gshimakawa@stu.kobe-u.ac.jp.