A, Expression of WRKY6 was analyzed by qRT-PCR in wild-type plants (WT) during seed germination and early seedling development. The wild-type imbibed seeds were germinated and grown on MS medium, and then the plants were harvested at the indicated time. Data are shown as mean ± SE (n = 3). B, qRT-PCR analysis of WRKY6 expression in response to exogenous ABA. Wild-type imbibed seeds were germinated on MS medium (MS) or MS medium with 0.5 μM ABA (MS+ABA) for 1 d, and then the seeds were harvested. Data are shown as mean ± SE (n = 3). C, qRT-PCR analysis of WRKY6 expression in 7-d-old wild-type seedlings treated with or without 100 μM ABA for 3 h. Data are shown as mean ± SE (n = 3). D, Expression of WRKY6 was analyzed by qRT-PCR in the wrky6 mutants (wrky6-1 and wrky6-2) and WRKY6-overexpressing lines (35S:WRKY6-5 and 35S:WRKY6-9). Data are shown as mean ± SE (n = 3). E, Phenotypic comparison. Imbibed seeds were transferred to MS or MS + 0.5 μM ABA medium and grown for 10 d. F-H, Seed germination assay. Imbibed seeds were transferred to MS (F), MS medium containing 0.5 μM ABA (G) or 2 μM ABA (H), and then the seed germination rates were calculated at the indicated time. Data are shown as mean ± SE (n = 3). More than 300 seeds were measured in each replicate. I, Cotyledon-greening analysis. Imbibed seeds were transferred to MS or MS + 0.5 μM ABA medium for 7 d before determining cotyledon-greening percentages. Data are shown as mean ± SE (n = 3). More than 300 seeds were measured in each replicate. J-K, Primary root length measurement with and without ABA addition. The 4-d-old seedlings were transferred to MS or MS + 15 μM ABA medium for 7 d, and then the photos were taken and the primary root length was measured. Asterisks in G, H, I and K indicate statistically significant differences compared with wild-type plants: *, P < 0.05; **, P < 0.01. Wild-type plant (WT) was used as a control (#).

https://doi.org/10.1371/journal.pgen.1008032.g001