FIGURE 3.

Genetic/molecular elements implicated in the regulation of ABA/GA balance and seed transition between dormancy and germination. ABA inhibits GAMYB-mediated GA responses through modulating the expression of WRKY transcription factors (Xie et al., 2006). DELLA protein regulates the balance between GA and ABA responses, and thereby seed dormancy and germination through its interaction with XERICO, a RING-H2 zinc finger E3 ubiquitin ligase. In the absence of GA, DELLA induces the expression of XERICO, which in turn enhances ABA accumulation, and ABI5 activity (Piskurewicz et al., 2008), leading to dormancy maintenance/inhibition of seed germination. MOTHER OF FT AND TF1 (MFT) represses ABI5 and therefore ABA signaling through a negative feedback mechanism (Xi et al., 2010). The role of MFT in regulating the balance between ABA and GA responses and thereby seed dormancy and germination involves ABI3 and ABI5 that act as repressor and activator of MFT expression, respectively, and DELLA that acts as activator of MFT expression (Xi et al., 2010). DELAY OF GERMINATION1 (DOG1) regulates ABA signaling and therefore seed dormancy through its interaction with PP2C (Née et al., 2017), and likely through modulating the expression of ABI5 and interacting with ABI3 (Dekkers et al., 2016). DOG1 also regulates GA metabolism through the expressions of GA biosynthetic and inactivation genes in temperature dependent manner (Kendall et al., 2011; Graeber et al., 2014). SnRK2/PKABA1 binds to GAMYB and repress its transcription (Gómez-Cadenas et al., 2001). See the legends of Figure 1 and Figure 2 for descriptions of ABA and GA signaling components.