ABA and ROS Are Required for GmSIN1 to Enhance Salt Tolerance and Root Growth. ABA and ROS Are Required for GmSIN1 to Enhance Salt Tolerance and Root Growth. (A) Phenotype of 7-d-old GmSIN1 OE transgenic plants compared with Wei6823 under control, 150 mM NaCl, 150 mM NaCl with 100 µM DPI, or 150 mM NaCl with 50 µM NDGA treatment. The treatments began at 3 d after germination and were maintained for 4 d. WT, wild type. (B) and (C) Root length (B) and root elongation (C) measured in the seedlings shown in (A). ND, no significant difference; WT, wild type. (D) Phenotype of 7-d-old GmSIN1 OE transgenic plants compared with Wei6823 under mock, 100 µM DPI, or 50 µM NDGA treatment. The treatments began at 3 d after germination and were maintained for 4 d. WT, wild type. (E) Root length of seedlings from (D). All data are given as means ± se (n = 20). OE-1, OE-2, and OE-3 are GmSIN1 OE transgenic lines. The roots of each genotype were collected from seedlings grown in 10 plastic growth bags with the same treatment. Each bag included three seedlings each from the wild type (WT) and the three transgenic lines. The data shown are a representative result from several independent experiments. ND, no significant difference. (F) Expression of GmSIN1 analyzed using RT-qPCR in response to 150 mM NaCl, 1 mM H2O2, and 100 µM ABA treatment. FLU (50 nM) or 100 µM DPI was supplemented or not with NaCl, ABA, or H2O2 in the roots of 6-d-old seedlings of cv Shengdou No. 9. (G) Expression of GmSIN1 analyzed using RT-qPCR in response to 150 mM NaCl for 48 h in soybean leaves transiently transformed with empty vector pB7GWIWG2(II), p35Spro:GmNCED3-RNAi, or p35Spro:GmRbohB-RNAi. Data are means ± se (n = 3). Significant differences between samples labeled with different Roman (a, b, c) or Greek letters (α, β, γ) were determined by one-way ANOVA and Tukey’s test, P < 0.05. The details of the sampling procedures are presented in the “Methods.” Shuo Li et al. Plant Cell 2019;31:2107-2130 ©2019 by American Society of Plant Biologists