Seed Dormancy in Arabidopsis is Controlled by Post-Translational Modifications of the DOG1 Protein

Seed dormancy controls the timing of seedling emergence under natural and agricultural conditions by preventing germination during unfavorable growing seasons. Freshly harvested seeds of many plant species, including Arabidopsis, show a high level of dormancy, which is gradually released during dry storage (after-ripening). The molecular mechanisms controlling the induction and release of seed dormancy are still poorly understood in comparison to those of other life history traits.

The gene DELAY OF GERMINATION 1 (DOG1) was recently identified as a major regulator of seed dormancy in Arabidopsis. The DOG1 gene is expressed in the vascular tissue of embryos. Loss-of-function dog1 mutants are completely non-dormant. DOG1 belongs to a conserved protein family in plants and its molecular function is unknown. The DOG1 protein accumulates during seed maturation and remains stable during seed storage and seed imbibition. The amount of DOG1 protein in freshly harvested seeds determines their dormancy level. DOG1 becomes modified during after-ripening and its abundance in stored seeds does not correlate with germination potential, suggesting that the protein becomes non-functional during seed storage. These data indicate that DOG1 protein abundance in freshly harvested seeds acts as a timer for seed dormancy release and that DOG1 post-translational modifications are a key element of the after-ripening mechanism. Identification of the modifications of the DOG1 protein is central to our understanding of dormancy and could enable the prediction and manipulation of dormancy levels in crop plants.