Control of seed dormancy inArabidopsisby acis-acting noncoding antisense transcript

Abstract

Seed dormancy is one of the most crucial process transitions in a plant’s life cycle. Its timing is tightly controlled by the expression level of the Delay of Germination 1 gene (DOG1).DOG1is the major quantitative trait locus for seed dormancy inArabidopsisand has been shown to control dormancy in many other plant species. This is reflected by the evolutionary conservation of the functional short alternatively polyadenylated form of theDOG1mRNA. Notably, the 3′ region ofDOG1, including the last exon that is not included in this transcript isoform, shows a high level of conservation at the DNA level, but the encoded polypeptide is poorly conserved. Here, we demonstrate that this region ofDOG1contains a promoter for the transcription of a noncoding antisense RNA,asDOG1, that is 5′ capped, polyadenylated, and relatively stable. This promoter is autonomous andasDOG1has an expression profile that is different from knownDOG1transcripts. Using several approaches we show thatasDOG1strongly suppressesDOG1expression during seed maturation incis, but is unable to do so intrans. Therefore, the negative regulation of seed dormancy byasDOG1incisresults in allele-specific suppression ofDOG1expression and promotes germination. Given the evolutionary conservation of theasDOG1promoter, we propose that thiscis-constrained noncoding RNA-mediated mechanism limiting the duration of seed dormancy functions across the Brassicaceae.