Vascular plant one-zinc finger 1 (VOZ1) and VOZ2 negatively regulate phytochrome B-mediated seed germination inArabidopsis

Abstract

Seed germination is regulated by light. Phytochromes (Phys) act as red and far-red light photoreceptors to mediate seed germination. However, the mechanism of this process is not well understood. In this study, we found that the Arabidopsis thaliana mutants vascular plant one-zinc finger 1 (voz1) and voz2 showed higher seed germination percentage than wild type when PhyB was inactivated by far-red light. In wild type, VOZ1 and VOZ2 expression were downregulated after seed imbibition, repressed by PhyB, and upregulated by Phytochrome-interacting factor 1 (PIF1), a key negative regulator of seed germination. Red light irradiation and the voz1voz2 mutation caused increased expression of Gibberellin 3-oxidase 1 (GA3ox1), a gibberellin (GA) biosynthetic gene. We also found that VOZ2 is bound directly to the promoter of GA3ox1 in vitro and in vivo. Our findings suggest that VOZs play a negative role in PhyB-mediated seed germination, possibly by directly regulating GA3ox1 expression.

From the Outside to the Inside: New Insights on the Main Factors that Guide the Germination Process

“…The expression level of both VOZ genes is downregulated during imbibition in the light; in addition, in pif mutant seeds, expression of VOZ genes was reduced irrespective of light conditions, indicating that VOZ1 and VOZ2 act downstream PIF1 which induces their expression in the dark [23]. By means of a ChIP assay, it was proved that VOZ2 directly binds the GA3ox1 promoter to repress its expression, consistent with increased expression level of the GA3ox1 gene in voz1voz2 double mutant seeds [23]. Interestingly, this scenario is very reminiscent of the one previously shown for the DAG1 protein, which is induced indirectly by PIF1 and in turn represses GA3ox1 expression to inhibit phyB-dependent seed germination [17,24].…”

“…The VASCULAR PLANT ONE-ZINC FINGER 1 and 2 (VOZ1 and VOZ2) were recently added as downstream elements of the phyB-PIF1 signaling pathway; VOZ1 and VOZ2 transcription factors have been previously characterised as phyB-interacting proteins which redundantly promote flowering [22]. Interestingly, it has been demonstrated that voz1voz2 double mutant seeds -conversely to the single voz1 and voz2 mutants -show a higher germination rate than the wild type under phyB-off conditions, (after a pulse of far red light), suggesting that the VOZ proteins redundantly repress phyB-mediated seed germination [23]. The expression level of both VOZ genes is downregulated during imbibition in the light; in addition, in pif mutant seeds, expression of VOZ genes was reduced irrespective of light conditions, indicating that VOZ1 and VOZ2 act downstream PIF1 which induces their expression in the dark [23].…”

“…Interestingly, it has been demonstrated that voz1voz2 double mutant seeds -conversely to the single voz1 and voz2 mutants -show a higher germination rate than the wild type under phyB-off conditions, (after a pulse of far red light), suggesting that the VOZ proteins redundantly repress phyB-mediated seed germination [23]. The expression level of both VOZ genes is downregulated during imbibition in the light; in addition, in pif mutant seeds, expression of VOZ genes was reduced irrespective of light conditions, indicating that VOZ1 and VOZ2 act downstream PIF1 which induces their expression in the dark [23]. By means of a ChIP assay, it was proved that VOZ2 directly binds the GA3ox1 promoter to repress its expression, consistent with increased expression level of the GA3ox1 gene in voz1voz2 double mutant seeds [23].…”

From the Outside to the Inside: New Insights on the Main Factors That Guide Seed Dormancy and Germination

“…The VASCULAR PLANT ONE-ZINC FINGER 1 and 2 (VOZ1 and VOZ2) were recently added as downstream elements of the phyB-PIF1 signaling pathway; VOZ1 and VOZ2 transcription factors have been previously characterized as phyB-interacting proteins which redundantly promote flowering [23]. Interestingly, it has been demonstrated that voz1voz2 double mutant seeds-conversely to the single voz1 and voz2 mutants-show a higher germination rate than the wild type under phyB-off conditions, (after a pulse of far red light), suggesting that the VOZ proteins redundantly repress phyB-mediated seed germination [24]. The expression level of both VOZ genes is downregulated during imbibition in the light; in addition, in pif mutant seeds, expression of VOZ genes was reduced irrespective of light conditions, indicating that VOZ1 and VOZ2 act downstream PIF1 which induces their expression in the dark [24].…”

“…Interestingly, it has been demonstrated that voz1voz2 double mutant seeds-conversely to the single voz1 and voz2 mutants-show a higher germination rate than the wild type under phyB-off conditions, (after a pulse of far red light), suggesting that the VOZ proteins redundantly repress phyB-mediated seed germination [24]. The expression level of both VOZ genes is downregulated during imbibition in the light; in addition, in pif mutant seeds, expression of VOZ genes was reduced irrespective of light conditions, indicating that VOZ1 and VOZ2 act downstream PIF1 which induces their expression in the dark [24]. By means of a ChIP assay, it was proved that VOZ2 directly binds the GA3ox1 promoter to repress its expression, consistent with increased expression level of the GA3ox1 gene in voz1voz2 double mutant seeds [24].…”