1. Supplemental Figures S1-S8

2. Supplemental Figure S1

3. Supplemental Figure S1. Amounts of sucrose (A,F), Glu (B,G), Fru (C,H), Fru 6-P (D,I) and starch (E,J) in WT tobacco and three transgenic lines with altered AOX amount, in both well- watered plants (A-E) and moderate drought-stressed plants (F-J). Data are the mean + S.E. of three independent experiments. Within a treatment, no significant differences were found across plant lines for any of these metabolites.

4. Supplemental Figure S2

5. Supplemental Figure S2. Light response curves for A n (A,E), ETR II (B,F), excitation pressure (C,G) and NPQ (D,H) in WT tobacco (closed circles) and three transgenic lines (B7, open circle; RI9, open triangle; RI29, open square) with altered AOX amount, in both well-watered plants (A-D) and moderate drought-stressed plants (E-H). Data are the mean + S.E. of three independent experiments.

6. Supplemental Figure S3

7. Supplemental Figure S3. CO 2 response curves for A n (A), ETR II (B), excitation pressure (C) and NPQ (D) of WT tobacco in both well-watered (open circles) and moderate drought- stressed (closed circles) plants. Data are the mean + S.E. of three independent experiments. These are re-plotted data from Fig.’s 2 and 3.

8. Supplemental Figure S4

9. Supplemental Figure S4. Light response curves for A n (A), ETR II (B), excitation pressure (C) and NPQ (D) of WT tobacco in both well-watered (open circles) and moderate drought- stressed (closed circles) plants. Data are the mean + S.E. of three independent experiments. These are re-plotted data from Fig. S3.

10. Supplemental Figure S5

11. Supplemental Figure S5. Photochemical quantum yield of PSI [Y(I)](A) and the relative rate of CET around PSI (B) in WT tobacco in both well-watered (open circles) and moderate drought-stressed (closed circles) plants. Data are the mean + S.E. of three independent experiments. These are re-plotted data from Fig.’s 5 and 6.

12. MitochondriaChloroplast Well-watered Drought Supplemental Figure S6 1 0.419 0.338 0.264

13. Supplemental Figure S6. Immunoblot analysis of AtpB amount in separate chloroplast and mitochondrial fractions isolated from either well-watered or moderate drought-stressed AOX knockdown (RI29) plants. Equal amounts of total protein (10µg) were loaded in each lane. Numbers below the blot indicate relative signal density of the different samples.

14. Supplemental Figure S7

15. Supplemental Figure S7. Maximal activities of the minor SOD isoforms FeSOD2 (A) and CuZnSOD2 (B) in WT tobacco and three transgenic lines with altered AOX amount, in both well-watered and moderate drought-stressed plants. Data are the mean + S.E. of six independent experiments. Activities are relative to that of the well-watered WT activity, which was set to 1. Within a treatment, no significant differences were found in either SOD activity across the different plant lines.

16. Supplemental Figure S8 AB

17. Supplemental Figure S8. A representative example of CO 2 response curves at low C i and three different PPFD (A) and a light response curve at low PPFD (B). Such data were used to estimate R L by either the Laisk method (A) or the Kok method (B), as described in Materials and Methods.