1. Fig. S1. Immunoblotting of PLDα1 in Zhongshuang 9. Proteins extracted from abaxial epidermal peels were separated by 8% SDS-PAGE, transferred to a polyvinylidene difluoride membrane, and blotted with PLDα1 antibodies. The protein was visualized by staining with alkaline phosphatase.

2. Fig. S2. Relative water content (a) and relative ionic conductivity (b) of AtPLDα1-OE and WT plants under well-watered condiction of Westar cultivar. Values are means ± SD (n = 3).

3. Fig. S3. Plant growth traits of AtPLDα1-OE and WT plants in the field. (a) and (b) Silique number and silique length, respectively, of the lord inflorescence of Westar WT and OE plants. (c) and (d) Silique number and silique length, respectively, of the lord inflorescence of Zhongshuang 9 OE and WT plants. Values are means ± SD (n = 6-10, r = 3 for Westar and n = 6-9, r = 3 for Zhongshuang 9). Bars with different letters denote significant difference at P < 0.05, based on ANOVA analysis and Duncan’s multiple range test.

4. Fig. S4. Yield of AtPLDα1-OE and WT plants in the field. (a) and (b) Seed number per silique and weight per 1000 seeds, respectively, of Westar WT and OE plants. (c) and (d) Seed number per silique and weight per 1000 seeds, respectively, of Zhongshuang 9 WT and OE plants. Values are means ± SD (n = 6-10, r = 3 for Westar and n = 6-9, r = 3 for Zhongshuang 9). Bars with different letters denote significant difference at P < 0.05, based on ANOVA analysis and Duncan’s multiple range test.

5. Supplemental Table 1 Primers used for PCR and Real-time PCR