ASP1-mediated deSUMOylation of AL6 controls seed dormancy in Arabidopsis.

ASP1‑mediated deSUMOylation promotes AL6 degradation and reduces its association with the DOG1 locus, thereby regulating DOG1 expression and primary seed dormancy in Arabidopsis. In our previous study, we found that SAP AND MIZ1 DOMAIN-CONTAINING LIGASE1 (SIZ1)-mediated SUMOylation of ALFIN1-LIKE 6 (AL6) was involved in regulating seed dormancy. However, the SUMO protease that mediates AL6 deSUMOylation to control seed dormancy remains unknown. Here, we show that ARABIDOPSIS SUMO PROTEASE 1 (ASP1) regulates seed dormancy and that its SUMO protease activity is required for this function. ASP1 interacts with AL6 and mediates its deSUMOylation. ASP1-mediated deSUMOylation promotes AL6 degradation and reduces its association with the DELAY OF GERMINATION 1 (DOG1) locus, thereby modulating DOG1 expression and seed dormancy. Together, these findings identify ASP1-mediated deSUMOylation of AL6 as an important post-translational regulatory mechanism linking AL6 protein stability and chromatin association to DOG1 expression and the establishment of primary seed dormancy in Arabidopsis thaliana.