The DAG1 transcription factor negatively regulates the seed-to-seedling transition in Arabidopsis acting on ABA and GA levels.

Alessandra Boccaccini,Anne Frey,Veronica Ruta,Annie Marion-Poll,Riccardo Lorrai,Miroslav Strnad,Paola Vittorioso,Danuše Tarkowská,Paolo Costantino,Stephanie Mercey-Boutet

doi:10.1186/s12870-016-0890-5

Abstract

BackgroundIn seeds, the transition from dormancy to germination is regulated by abscisic acid (ABA) and gibberellins (GAs), and involves chromatin remodelling. Particularly, the repressive mark H3K27 trimethylation (H3K27me3) has been shown to target many master regulators of this transition. DAG1 (DOF AFFECTING GERMINATION1), is a negative regulator of seed germination in Arabidopsis, and directly represses the GA biosynthetic gene GA3ox1 (gibberellin 3-β-dioxygenase 1). We set to investigate the role of DAG1 in seed dormancy and maturation with respect to epigenetic and hormonal control.ResultsWe show that DAG1 expression is controlled at the epigenetic level through the H3K27me3 mark during the seed-to-seedling transition, and that DAG1 directly represses also the ABA catabolic gene CYP707A2; consistently, the ABA level is lower while the GA level is higher in dag1 mutant seeds. Furthermore, both DAG1 expression and protein stability are controlled by GAs.ConclusionsOur results point to DAG1 as a key player in the control of the developmental switch between seed dormancy and germination.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-016-0890-5) contains supplementary material, which is available to authorized users.

Highlights

In seeds, the transition from dormancy to germination is regulated by abscisic acid (ABA) and gibberellins (GAs), and involves chromatin remodelling
DOF AFFECTING GERMINATION1 (DAG1) is expressed during seed maturation and dormancy and is modulated via epigenetic control We have previously shown that inactivation of DAG1 reduces seed dormancy [12]
To assess whether and when DAG1 is involved in the establishment of dormancy, we analysed its expression from late-maturation to nondormant wild type seeds by means of Quantitative reverse transcriptase-polymerase chain reaction (RT-quantitative PCR (qPCR))

Summary

Introduction

The transition from dormancy to germination is regulated by abscisic acid (ABA) and gibberellins (GAs), and involves chromatin remodelling. DAG1 (DOF AFFECTING GERMINATION1), is a negative regulator of seed germination in Arabidopsis, and directly represses the GA biosynthetic gene GA3ox (gibberellin 3-β-dioxygenase 1). The transition from a growth-arrested seed to a germinating seed represents a crucial developmental switch in the life cycle of a plant [1]. Seeds of several annuals, including Arabidopsis, develop dormancy during the late stages of their development: mature, these seeds are not capable of germinating even under favourable environmental conditions. Development of the Arabidopsis embryo consists of two phases: embryogenesis (from 0 to 6 days after pollination, DAP), and the embryo growth phase (from 7 to 10 DAP). Seed maturation takes place until 21 DAP, when the seed is fully developed. Dormancy is established once embryo development is completed [2], and it is released within few weeks to several months after seed harvest, depending on the ecotype [3, 4]

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