Figure 6.

Pathways Mediating the Effect of Seed Maturation Temperature on Dormancy.

(A) Expression of DOG1, GA2ox6, NCED4, and CYP707A2 in dog1, aba2, and della mutant dry seeds matured at 17°C. Values represent the mean and se of two biological replicates. Germination data for the above seed lots are shown in Supplemental Figure 3 online.

(B) A proposed pathway mediating the regulation of dormancy by cold during seed maturation. Cold induction of CBF transcription is inhibited by an unknown seed-specific Repressor of CBF expression (SSR), although expression in the absence of cold means CBFs are still required for normal dormancy. Cold induces high levels of dormancy through more than one mechanism, including the elevation of DOG1 transcription and the action of DOG1 in the promotion of GA catabolism. ABA also promotes GA2ox6 expression during seed maturation (Seo et al., 2006). As dog1 and della mutants show little misregulation of ABA-related gene expression, we propose that this constitutes a second pathway, perhaps relying on FLC, which is required for normal CYP707A2 expression (Chiang et al., 2009).