Abstract
BackgroundThe transcription factor DOF AFFECTING GERMINATION1 (DAG1) is a repressor of the light-mediated seed germination process. DAG1 acts downstream PHYTOCHROME INTERACTING FACTOR3-LIKE 5 (PIL5), the master repressor, and negatively regulates gibberellin biosynthesis by directly repressing the biosynthetic gene AtGA3ox1. The Dof protein DOF AFFECTING GERMINATION (DAG2) shares a high degree of aminoacidic identity with DAG1. While DAG1 inactivation considerably increases the germination capability of seeds, the dag2 mutant has seeds with a germination potential substantially lower than the wild-type, indicating that these factors may play opposite roles in seed germination.ResultsWe show here that DAG2 expression is positively regulated by environmental factors triggering germination, whereas its expression is repressed by PIL5 and DAG1; by Chromatin Immuno Precipitation (ChIP) analysis we prove that DAG1 directly regulates DAG2. In addition, we show that Red light significantly reduces germination of dag2 mutant seeds.ConclusionsIn agreement with the seed germination phenotype of the dag2 mutant previously published, the present data prove that DAG2 is a positive regulator of the light-mediated seed germination process, and particularly reveal that this protein plays its main role downstream of PIL5 and DAG1 in the phytochrome B (phyB)-mediated pathway.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0453-1) contains supplementary material, which is available to authorized users.
Highlights
The transcription factor DNA Binding With One Finger (DOF) AFFECTING GERMINATION1 (DAG1) is a repressor of the light-mediated seed germination process
We have previously shown that inactivation of the DNA BINDING WITH ONE FINGER (Dof) proteins DOF AFFECTING GERMINATION1 (DAG1) and Dof AFFECTING GERMINATION 2 (DAG2) affects in opposite ways seed germination: dag2 mutant seeds required more light and GA than wild-type seeds to germinate, whereas germination of dag1 seeds was less dependent on these factors [7,8,21]
As we have recently shown that DAG1 is a component of the phytochrome B (phyB)-mediated pathway controlling seed germination in Arabidopsis [22,23], we set up to verify whether DAG2 is a component of this regulatory network
Summary
The transcription factor DOF AFFECTING GERMINATION1 (DAG1) is a repressor of the light-mediated seed germination process. The number of Dof genes varies depending on the species; bioinformatic analysis of the Arabidopsis and rice genome predicts 36 and 30 Dof genes, respectively [1], while 26 are present in barley [2], 31 in wheat [4], and 28 in sorghum [5]. Members of this family have been found to be involved in the regulation of diverse plantspecific processes. Among the factors involved in phyB-mediated GA-induced seed germination, the bHLH
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