1. Overexpression of sweetpotato expansin cDNA (IbEXP1) increases seed yield in Arabidopsis Jung Myung Bae 1, *, Man Sup Kwak 1, Seol Ah Noh 1, Mi-Joung Oh 1, Youn-Sung Kim 2, Jeong Sheop Shin 1 1 Division of Life Sciences, Korea University, Seoul 136-701, Korea 2 NH Seed Research and Development Center, Gyeonggi-do 456-824, Korea

2. Col-0IbEXP1-ox #1IbEXP1-ox #4IbEXP1-ox #22 Protein (μg) a 3.18±0.045.04±0.165.01±0.114.04±0.18 Starch (μg) b 0.98±0.061.55±0.131.48±0.031.54±0.06 Table S1 Protein and starch content in IbEXP1-ox seeds. a Total protein content per each seed. One hundred mature dry seeds from Col-0 or IbEXP1- ox plants were used. b Total starch content per each seed. Mature dry seeds (1 g) from Col-0 or IbEXP1-ox plants were used. Starch content per seed was calculated on the basis of the 1,000-seed weight in Table 1.

3. 0 10 20 30 Col-0Exp-1Exp-4Exp-22 Rosette leaf length (mm) 0 4 8 12 Rosette leaf width (mm) Col-0Exp-1Exp-4Exp-22 a b cc a b c bc Fig. S1 Rosette leaf development in IbEXP1-ox Arabidopsis plants (a) Rosette leaf length of IbEXP1-ox plants at 3 weeks after planting. (b) Rosette leaf width of IbEXP1-ox plants at 3 weeks after planting. (a and b) Rosette leaf measurements were made on the fourth rosette leaf to emerge from T3 homozygous plants of each line. Mean values of >12 plants with standard deviations are shown. Different letters above the bars indicate significantly different means (P < 0.05) as analyzed by Duncan’s multiple range test using the IBM SPSS Statistics 21 program a b Fig. S1

4. 0 20 40 60 0 5 10 15 20 Rosette leaf length (mm) Rosette leaf width (mm) Col-0Exp-1Exp-4Exp-22 Col-0Exp-1Exp-4Exp-22 Fig. S2 a b Fig. S2 Rosette leaf size in IbEXP1-ox lines at reproductive stage. (a and b) Size of rosette leaves. The length (a) and width (b) of fourth rosette leaf to emerge from T3 homozygous plants of each line was measured. Data were collected from Col-0 and IbEXP1-ox lines at 6 weeks after planting. Mean values of >12 plants with standard deviations are shown. Different letters above the bars indicate significantly different means (P < 0.05) as analyzed by Duncan’s multiple range test using the IBM SPSS Statistics 21 program. aaaa aaaa

5. Exp-1 Exp-4 Col-0 Fig. S3 Rosette leaf development in IbEXP1-ox lines at reproductive stage. Picture was taken at 8 weeks after planting. Fig. S3

6. b c 0 10 20 30 Silique length (mm) Col-0Exp-1Exp-4Exp-22 0.0 0.4 0.8 1.2 1.6 Silique thickness (mm) Col-0Exp-1Exp-4Exp-22 2.0 Exp-1 Col-0 a Fig. S4 Fig. S4 Silique phenotype in IbEXP1-ox lines. (a - c) Silique size comparison between Col-0 and IbEXP1-ox plants. Thickness (b) and length (c) of siliques were measured with siliques on the primary inflorescence stem at 6 weeks after planting. Different letters above the bars indicate significantly different means (P 50 siliques from at least six different plants with standard deviations are shown. a a bbb aa a

7. Fig. S5 Col-0IbExp1-ox Fig. S5 Branching phenotype in IbEXP1-ox plants. Picture was taken prior to seed harvest at 7 weeks after planting. Aerial part of individual Col-0 or IbEXP1-ox plant #1 in Fig. 4 was enlarged.