1. (b) (f) P700 + levels (d) P700 + levels (a) F. brownii (C 4 -like) F. palmeri (C 4 -like) F. anomala (C 3 -C 4 ) F. ramosissima (C 3 -C 4 ) F. pringlei (C 3 ) F. robusta (C 3 ) 0 0.2 0.4 0.6 0.8 1.0 (c) time, s 051015 2025 30 (e) time, s 051015 2025 30 (f) 0 0.2 0.4 0.6 0.8 1.0 0 0.2 0.4 0.6 0.8 1.0 Figure S1. P700 oxidation kinetics in leaf discs infiltrated with distilled water (dH 2 O) or methyl viologen (MV) under far-red light illumination in C 3, C 3 -C 4, and C 4 -like Flaveria species. P700 oxidation kinetics in leaf discs of F. pringlei (a), F. robusta (b), F. anomala (c), F. ramosissima (d), F. brownii (e), and F. palmeri (f) infiltrated with dH 2 O (grey line) or 50 μmol MV (black line). Plants were dark-adapted for 2 h. Kinetics shown are the average of three individual plants.

2. 116 88 62 47 35 28 (kDa) PEPC PPDK NADP-ME rbcL (RuBisCO large subunit) F. bidentis (C 4 ) F. anomala (C 3 -C 4 ) F. palmeri (C 4 -like) F. brownii (C 4 -like) F. robusta (C 3 ) F. pringlei (C 3 ) F. ramosissima (C 3 -C 4 ) Figure S2. SDS-PAGE of total leaf soluble proteins from C 3, C 3 -C 4, C 4 -like, and C 4 Flaveria species. Total soluble protein (20 μg) extracted from leaves of C 3 F. pringlei, C 3 F. robusta, C 3 -C 4 F. anomala, C 3 -C 4 F. ramosissima, C 4 -like F. brownii, C 4 -like F. palmeri, C 4 F. bidentis, and C 4 F. trinervia were separated by electrophoresis on 12.5% acrylamide gels and stained with Coomassie brilliant blue R-250.

3. (a) Chlorophyll fluorescence time (b) ML OFF AL ON SP FR ON ML ON Chlorophyll fluorescence AL OFF 1min30s4min 1 min 30 s ML OFFFR ONAL OFF B A NDH activity (a. u.) (c) F. bidentis F. brownii F. anomala F. pringlei F. palmeri F. robusta F. ramosissima F. pringlei (C 3 ) F. anomala (C 3 -C 4 ) F. ramosissima (C 3 -C 4 ) F. robusta (C 3 ) F. bidentis (C 4 ) F. brownii (C 4 -like) F. palmeri (C 4 -like) Figure S3. NDH activity in C 3, C 3 -C 4, C 4 -like, and C 4 Flaveria species. (a) Left curve shows typical trace of chlorophyll fluorescence of C 4 F. bidentis. Plants were dark-adapted for 2 h and then exposed to actinic light (AL; 53 μmol photon m -2 s -1 ) for 4 min. Transient increase in chlorophyll fluorescence after actinic light illumination is ascribed to NDH activity. Right box shows magnified trace of transient increase in chlorophyll fluorescence from left curve. A and B indicate maximum values and minimum values, respectively, for amplitude of transient increase in chlorophyll fluorescence. (b) Magnified trace of transient increase in chlorophyll fluorescence after actinic light illumination in leaves of C 3 F. pringlei, C 3 F. robusta C 3 -C 4 F. anomala, C 3 -C 4 F. ramosissima, C 4 -like F. brownii, C 4 -like F. palmeri, C 4 F. bidentis, and C 4 F. trinervia. Chlorophyll fluorescence levels were normalised to F m (maximum fluorescence at closed PSII centre in the dark). (c) Quantification of NDH activity estimated from peak amplitude of transient increase in chlorophyll fluorescence in each Flaveria species. Values for NDH activity were calculated as follows: NDH activity = (A-B)/maximum fluorescence. Values are means ± SD (n=3).

4. (a)(b)(c) (d)(e)(f) Figure S4. Background labelling with rabbit serum in in situ immunolocalisation. Transverse sections were labelled with rabbit serum and then labelled with secondary antibodies conjugated to FITC. FITC fluorescence in green (a-c) and overlaid images of FITC fluorescence in green and bright field (d-f) were visualised by confocal microscopy. Scale bar = 50 μm.

5. Bundle-sheath chloroplasts Mesophyll chloroplasts (a)(b) (c)(d) (e)(f) Figure S5. Measurement of total length of grana thylakoid and stroma thylakoid membranes of BS chloroplasts or M chloroplasts in C 4 F. bidentis. Electron micrograph shows part of BS chloroplast (a, c, e) and M chloroplast (b, d, f) used for measurements. Pink lines in c and d show trace of grana thylakoid and those in e and f show stroma thylakoid.