DOF6 ENFORCES PRIMARY SEED DORMANCY VIA ITS DOWNSTREAM TARGETS, MLP329 AND BAT1, IN ARABIDOPSIS THALIANA

Abstract

Seed dormancy prevents seeds from germinating during unfavorable conditions. Freshly harvested, mature seeds exhibit primary dormancy. Previously, our lab identified a novel RGA-LIKE2 (RGL2) - DNA BINDING1 ZINC FINGER6 (DOF6) protein complex that promotes primary seed dormancy in Arabidopsis. Using RNA sequencing, we found that MAJOR LATEX PROTEIN-LIKE PROTEIN329 (MLP329) and BRASSINOSTEROID-RELATED ACYLTRANSFERASE1 (BAT1) are regulated by DOF6. DOF6 upregulated both MLP329 and BAT1 expressions. However, the presence of RGL2 suppresses DOF6-dependent MLP329 induction, while RGL2 further promotes DOF6-dependent BAT1 expression. We demonstrated that MLP329 promotes primary dormancy by modulating endogenous GA/ABA ratio. Previously, BAT1 was shown to play a role in inhibiting BR biosynthesis. Suppression of the expression of BR biosynthetic genes was also observed when DOF6 was overexpressed, thereby highlighting the role of BR in dormancy release. Thus, our findings demonstrate how DOF6 enforces primary seed dormancy through hormonal crosstalk via its downstream targets MLP329 and BAT1.