5% CO 2 + HL

1. A 5% CO2 + HL Normal Air + HL 5% CO2 +HL B 5% CO2 + LL Normal Air + HL Normal Air + LL Supplemental Figure S1. Conditional lethal effect of MSX on Arabidopsis wild-type plants. A. Plants were grown on the selection medium with 5% CO2 at 150 mmol photons m–2 s–1 (HL) for 2 weeks and then kept in ambient air or 5% CO2 for 150 h. B. Plants were grown on the selection medium with 5% CO2 and 50 mmol photons m–2 s–1 (LL) for 2 weeks, and then kept in ambient air conditions at LL or HL for 150 h.

2. WT nara3 WT nara5 114 bp 76 bp 157 bp 134 bp 38 bp WT nara10 WT nara7 618 bp 1004 bp 403 bp 579 bp 215 bp 425 bp Supplemental Figure S2. Detection of nara3, nara5, nara7, and nara10 mutations using dCAPS markers. Gene segments containing nara mutations were amplified by PCR using the following dCAPS primer sets: nara3, 5’-TGGAGTACTAATCTCAATCG-3’/5’-TGGAGTACTAATCTCAATCG-3’; nara5, 5’-AACACTTTAGTTGCTCTCGC-3’/5’-GTACCCGTAAAAGCTACCG-3’; nara7, 5’-CGGTCTTAGAGCTGCTCTTG-3’/5’-ACTTCATACCGCGAAATGGG-3’; nara10, 5’-ATGGCCAACCCGTTT-3’/5’-CCAAGATCCTCGAGTGT-3’. Each PCR product was then digested by restriction enzymes, Bsr DI for nara3, Mnl I for nara5, Pvu II for nara7, and SfcI for nara10.

3. Normal air (0.037 % CO2) High CO2 (0.3 % CO2) WT nara7 Supplemental Figure S3. Lethal photorespiratory phenotype of nara7. Plants were grown on soil in ambient air or 0.3% CO2 for 14 days. Bar = 1 cm.

4. C A B G to A T-DNA NARA5 Exon1 Exon 2 D E F2 progeny nara5-1 (homozygote) ×nara5-2 (heterozygote) Col Yellow (nara5 ) Green (WT) A + B B + C D + E ( + MnlI ) Supplemental Figure S4. Allelism between nara5-1 and nara5-2. DNA was extracted from yellow (nara5) and green (WT) F1 progenies in a seed capsule resulting from outcrossing between nara5-1 and nara5-2. nara5 mutation was confirmed by PCR using dCAPS primers (D and E) as described in Supplemental Figure S2. T-DNA insertions were detected by PCR using the following primers: forward primer A, 5’-TTTCGGAGCTTCTGGGAACT-3’; reverse primer B, 5’-ATGATAGGCTAGTTTGACGCCTTA-3’; forward primer C, 5’-CCCATTTGGACGTGAATGTAGACAC-3’.

5. A B Relative transcript level Relative transcript level shoot root RL CL ST I Supplemental Figure S5. Relative NARA5 mRNA levels in different tissues of wild-type Arabidopsis. A. Transcript level of NARA5 in shoots or roots of 8-d-old seedlings cultured in MS medium supplemented with 3% sucrose. Values shown are relative to those of expression in shoots. B. Transcript level of NARA5 in 4-week-old soil-grown plants in rosette leaves (RL), cauline leaves (CL), stems (ST), and inflorescences (I). Inflorescences include inflorescence meristems, closed flower buds, and open flowers. Values shown are relative to transcript levels in R. Data represent means ± SD (n = 3). Each transcript was normalized against Act8 transcript, and the relative transcript level represents the transcript level in each sample relative to that in shoot or RL. Act8 was used to standardize the amount of cDNA from the different tissues because it shows relatively uniform distribution in nearly all vegetative tissues in Arabidopsis thaliana (An et al., 1996)

6. SUPPLEMENTAL LITERATURE CITEDAn YQ, McDowell JM, Huang S, McKinney EC, Chambliss S, Meagher RB (1996) Strong, constitutive expression of the Arabidopsis ACT2/ACT8 actin subclass in vegetative tissues. Plant J 10:107–121