1. (a) (b) (c) (d) (e) (f) (g) Figure S1.

2. Figure S1. Comparison of OsPCR1-6 and GW2 transcript levels in the grains of developing gw2 and wild-type isogenic lines. OsPCR1-6 (a-f) and GW2 (g) expression in gw2 and the corresponding WT seedlings (HS vs. CR413, HY vs. gw2 k/o). RNA was extracted from developing grains (3 days before pollination (DBP) to 12 DAP, from Hwaseong (HS), gw2-NIL (CR413), Hwayeong (HY), and GW2 knockout (gw2 k/o) plants grown in rice paddy soil). Expression analysis was performed using qRT-PCR and a gene-specific primer set. The values were normalized to actin transcript levels and indicate the average and standard error (n=3).

3. OsPCR1 sense lines OsPCR1 anti-sense lines Figure S2. Analysis of correlation between grain weight and OsPCR1 expression level in OsPCR1 transgenic plants. The OsPcr1 mRNA levels were analyzed by qRT-PCR and compared to the grain weight shown in figure. qRT-PCR was performed with the total RNAs using the OsPCR1RT-F and OsPCR1RT-R primers and actin primers for an internal standard. The graph was generated by GraPad Prism, and correlation analysis between phenotype and OsPCR1 expression level was performed using nonlinear regression (curve fit) parameter with polynomial fourth order in GraPad Prism program.

4. OsPCR1-YFP FM4-64Merged Back/white Figure S3. Tissue-specific expression of OsPCR1 and subcellular localization of OsPCR1-YFP. in root cells of transgenic rice. (a) OsPCR1 expression patterns in different tissues of 2-week-old seedlings and plants of 5 day-after-pollination stage (5 DAP). R: root, S: shoot, N II: node II, N I: node I, LS I: leaf sheath I, FL: flag leaf, I II: internode II, I I: internode I, Ra: rachis, Sp: spikelet. (b) Subcellular localization of OsPCR1-YFP in root cells of transgenic rice. Roots were treated with FM4-64 for 30 min to label the plasma membrane. Bar = 10 µm. SeedlingsPlants of 5 DAP RS N IIN ILS IFLI III RaSp OsPCR1 OsActin1 (a) (b)

5. Figure S4. Sequence divergence of rice PCR1 genes in different Oryza. The phylogenetic tree was constructed using the neighbor-joining method implemented in MEGA version 4.0 and was based on multiple alignments of PCR1 genomic DNA sequences from different rice accessions. The bootstrap values (percentage) of 1000 replicates are shown at the branching points. The scale bars indicate unit of branch length.

6. HS GR 20 21 22 23242526 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 HS GR 20 21 22 23242526 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 Figure S5. Genotype analysis of OsPCR1 in 25 Korean rice accessions. (a) A 320- bp fragment was detected in japonica-type using the HS-PCR1 marker. (b) A 290-bp fragment was amplified from indica-type rice using the primer set of GR-PCR1. The sample numbers are the same as in Table S1. The products were divided into japonica- or indica-type PCR1 by DNA band analysis using Perkin Elmer LabChip GX (Caliper Life Sciences, Inc., Hopkinton, MA, USA). (a) (b)

7. Ch55Os Ch55 SalI PCR1 CO: PCR1 OC: ½ SG½ SG, 30 µM Cd PCR1 EV Os Ch55 OC CO PCR1 EV Os Ch55 OC CO (a) (b) Figure S6.

8. Figure S6. Comparison of Cd resistance in DTY 167 yeast strains expressing the PCR1 genes from Hwaseong and the weedy rice Ch55. (a) Comparison of PCR1 amino acid sequences of O. sativa cv. Hwaseong and Ch55, which exhibits lead resistance (Yang et al. 2000). (b) Phenotype analysis of DTY 167 yeast cells transformed with OsPCR1, Ch55 PCR1, a swapping mutant of japonica-type (N’) and Ch55 (C’) PCR1 (OCPCR1; white and blue bar), and a swapping mutant of indica- (N’) and japonica- (C’) type PCR1 (COPCR1; blue and white bar). Yeast cells were grown in the absence of uracil on synthetic glucose (SD ura- ) liquid medium, spotted on uracil-free synthetic galactose (SG ura- ) agar plates in the absence or presence of CdCl 2 and cultured at 30 º C for 3-5 days.