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

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ABSTRACT

Background: In 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.

Results: We 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.

Conclusions: Our results point to DAG1 as a key player in the control of the developmental switch between seed dormancy and germination.

Electronic supplementary material: The online version of this article (doi:10.1186/s12870-016-0890-5) contains supplementary material, which is available to authorized users.

No MeSH data available.


DAG1 controls ABA and GA metabolism during seed storage. Relative expression level of: aCYP707A2, NCED6 and NCED9; bGA3ox1, GA3ox2 and GA2ox2, in dag1 and WT dry seeds at 0, 14 and 28 DAH. The values of relative expression levels are means of three biological replicates, presented with SD values. Expression levels were normalized with that of the UBQ10 (At4g05320) reference gene. Significant differences were analyzed by t-test (*P ≤ 0,05)
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Fig3: DAG1 controls ABA and GA metabolism during seed storage. Relative expression level of: aCYP707A2, NCED6 and NCED9; bGA3ox1, GA3ox2 and GA2ox2, in dag1 and WT dry seeds at 0, 14 and 28 DAH. The values of relative expression levels are means of three biological replicates, presented with SD values. Expression levels were normalized with that of the UBQ10 (At4g05320) reference gene. Significant differences were analyzed by t-test (*P ≤ 0,05)

Mentions: To verify whether the post-harvest control of DAG1 on dormancy is exerted via the same hormones and genes, we compared the expression of the ABA and GAs metabolic genes in dag1 mutant and wild type dry seeds at 0, 14 and 28 DAH. Interestingly, only the ABA catabolic gene CYP707A2 and the GA biosynthetic gene GA3ox1 were deregulated by DAG1 inactivation: expression of CYP707A2 was increased up to 4-fold at 28 DAH, while GA3ox1 was significantly upregulated at 0, 14 and 28 DAH (Fig. 3a and b).Fig. 3


The DAG1 transcription factor negatively regulates the seed-to-seedling transition in Arabidopsis acting on ABA and GA levels
DAG1 controls ABA and GA metabolism during seed storage. Relative expression level of: aCYP707A2, NCED6 and NCED9; bGA3ox1, GA3ox2 and GA2ox2, in dag1 and WT dry seeds at 0, 14 and 28 DAH. The values of relative expression levels are means of three biological replicates, presented with SD values. Expression levels were normalized with that of the UBQ10 (At4g05320) reference gene. Significant differences were analyzed by t-test (*P ≤ 0,05)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5016951&req=5

Fig3: DAG1 controls ABA and GA metabolism during seed storage. Relative expression level of: aCYP707A2, NCED6 and NCED9; bGA3ox1, GA3ox2 and GA2ox2, in dag1 and WT dry seeds at 0, 14 and 28 DAH. The values of relative expression levels are means of three biological replicates, presented with SD values. Expression levels were normalized with that of the UBQ10 (At4g05320) reference gene. Significant differences were analyzed by t-test (*P ≤ 0,05)
Mentions: To verify whether the post-harvest control of DAG1 on dormancy is exerted via the same hormones and genes, we compared the expression of the ABA and GAs metabolic genes in dag1 mutant and wild type dry seeds at 0, 14 and 28 DAH. Interestingly, only the ABA catabolic gene CYP707A2 and the GA biosynthetic gene GA3ox1 were deregulated by DAG1 inactivation: expression of CYP707A2 was increased up to 4-fold at 28 DAH, while GA3ox1 was significantly upregulated at 0, 14 and 28 DAH (Fig. 3a and b).Fig. 3

View Article: PubMed Central - PubMed

ABSTRACT

Background: In 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.

Results: We 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.

Conclusions: Our results point to DAG1 as a key player in the control of the developmental switch between seed dormancy and germination.

Electronic supplementary material: The online version of this article (doi:10.1186/s12870-016-0890-5) contains supplementary material, which is available to authorized users.

No MeSH data available.