• germination
• ERF
• dormancy
• arabidopsis
• AP2
• abscisic acid
• ABA
• seed
• Soloist

Seeds generally undergo a variable period of quiescence, named dormancy, during which even in favourable conditions seed germination is prevented. Dormancy is a complex trait that mainly responds to the endogenous levels of abscisic acid (ABA) and gibberellins (GA). In the present work we identified the involvement of an AP2/ERF transcription factor in the germination process of Arabidopsis thaliana.
We inferred from RNA-seq data that only one of the previously proposed Soloist isoforms is significantly expressed in Arabidopsis. Interestingly, a qPCR survey showed an overall abundant expression of the gene throughout all plant organs. Confocal microscopy observations of a GFP-tagged overexpressing line showed a clear nuclear localization, data that strengthen the hypothesis of a transcriptional regulatory role. Furthermore, based on preliminary trans-activation assay results, we suggest a role for SOLOIST as transcriptional activator. We showed a significant down-regulation of Soloist mRNA level 3h after an ABA treatment. Because the ABA signaling cascade is known to play a role in seed germination, we compared germination percentages between wild type plants and a T-DNA insertion line showing reduced Soloist expression levels. The results suggest that SOLOIST may play a role as a promoter of seed germination, as knock-down plants showed reduced and delayed germination.