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Genome-wide transcript profiling of endosperm without paternal contribution identifies parent-of-origin-dependent regulation of AGAMOUS-LIKE36.

Shirzadi R, Andersen ED, Bjerkan KN, Gloeckle BM, Heese M, Ungru A, Winge P, Koncz C, Aalen RB, Schnittger A, Grini PE - PLoS Genet. (2011)

Bottom Line: In Arabidopsis, analyses of mutants in the cell-cycle regulator CYCLIN DEPENDENT KINASE A;1 (CKDA;1) have revealed the importance of a paternal genome for the effective development of the endosperm and ultimately the seed.Among those, AGAMOUS-LIKE (AGL) genes encoding Type-I MADS-box transcription factors were significantly overrepresented.Interestingly, our data also show that the active maternal allele of AGL36 is regulated throughout endosperm development by components of the FIS Polycomb Repressive Complex 2 (PRC2), revealing a new type of dual epigenetic regulation in seeds.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biosciences (IMBV), University of Oslo, Oslo, Norway.

ABSTRACT
Seed development in angiosperms is dependent on the interplay among different transcriptional programs operating in the embryo, the endosperm, and the maternally-derived seed coat. In angiosperms, the embryo and the endosperm are products of double fertilization during which the two pollen sperm cells fuse with the egg cell and the central cell of the female gametophyte. In Arabidopsis, analyses of mutants in the cell-cycle regulator CYCLIN DEPENDENT KINASE A;1 (CKDA;1) have revealed the importance of a paternal genome for the effective development of the endosperm and ultimately the seed. Here we have exploited cdka;1 fertilization as a novel tool for the identification of seed regulators and factors involved in parent-of-origin-specific regulation during seed development. We have generated genome-wide transcription profiles of cdka;1 fertilized seeds and identified approximately 600 genes that are downregulated in the absence of a paternal genome. Among those, AGAMOUS-LIKE (AGL) genes encoding Type-I MADS-box transcription factors were significantly overrepresented. Here, AGL36 was chosen for an in-depth study and shown to be imprinted. We demonstrate that AGL36 parent-of-origin-dependent expression is controlled by the activity of METHYLTRANSFERASE1 (MET1) maintenance DNA methyltransferase and DEMETER (DME) DNA glycosylase. Interestingly, our data also show that the active maternal allele of AGL36 is regulated throughout endosperm development by components of the FIS Polycomb Repressive Complex 2 (PRC2), revealing a new type of dual epigenetic regulation in seeds.

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pAGL36::GUS is expressed only from its maternal allele (and only in the fertilization products).(A) A pAGL36::GUS construct was generated using 1752 bp of the promoter region of AGL36 that spans the ATG start codon. Transposable element sequences (hAT, Helitron, Arnoldy, DNA transposons, MuDR and Pogo transposons) in 5′and 3′regulatory regions are color coded as indicated. The numbers indicate the positions on Chromosome 5 (http://gbrowse.arabidopsis.org). Note, Helitron and Arnoldy transposable elements in the pAGL36::GUS promoter region. Plants expressing the transgene were used either as maternal (B) or paternal (C) partners in crosses with wild-type plants. Samples were taken at 3 DAP (left panel) and 6 DAP (right panel). pAGL36::GUS is absent in the seed-coat and only maternally expressed in the endosperm. The pAGL36::GUS signal is increased in 6 DAP versus 3 DAP samples.
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pgen-1001303-g004: pAGL36::GUS is expressed only from its maternal allele (and only in the fertilization products).(A) A pAGL36::GUS construct was generated using 1752 bp of the promoter region of AGL36 that spans the ATG start codon. Transposable element sequences (hAT, Helitron, Arnoldy, DNA transposons, MuDR and Pogo transposons) in 5′and 3′regulatory regions are color coded as indicated. The numbers indicate the positions on Chromosome 5 (http://gbrowse.arabidopsis.org). Note, Helitron and Arnoldy transposable elements in the pAGL36::GUS promoter region. Plants expressing the transgene were used either as maternal (B) or paternal (C) partners in crosses with wild-type plants. Samples were taken at 3 DAP (left panel) and 6 DAP (right panel). pAGL36::GUS is absent in the seed-coat and only maternally expressed in the endosperm. The pAGL36::GUS signal is increased in 6 DAP versus 3 DAP samples.

Mentions: To rule out that the observed maternal expression is due to expression of AGL36 in the ovule integument, which is a maternal tissue, we generated a reporter construct consisting of 1752 bp of the AGL36 promoter region fused to a GUS reporter (pAGL36::GUS) (Figure 4A). Single-copy lines carrying this construct were used in reciprocal crosses with wild-type Ler and Col plants to examine GUS expression at 3 and 6 DAP. When inherited maternally, pAGL36::GUS expression in the seed was indeed found to be restricted only to the fertilization product (Figure 4B, Figure S7D). In the reciprocal cross, when pAGL36::GUS was inherited from the paternal genome, no GUS expression was detected, (Figure 4C, Figure S7E). Consistent with the SNP analysis, this demonstrated that AGL36 was imprinted and only maternally active throughout its expression cycle. Furthermore, the 1.7 Kb promoter fragment used in this analysis appears to be sufficient to confer parent-of-origin specific expression of the reporter.


Genome-wide transcript profiling of endosperm without paternal contribution identifies parent-of-origin-dependent regulation of AGAMOUS-LIKE36.

Shirzadi R, Andersen ED, Bjerkan KN, Gloeckle BM, Heese M, Ungru A, Winge P, Koncz C, Aalen RB, Schnittger A, Grini PE - PLoS Genet. (2011)

pAGL36::GUS is expressed only from its maternal allele (and only in the fertilization products).(A) A pAGL36::GUS construct was generated using 1752 bp of the promoter region of AGL36 that spans the ATG start codon. Transposable element sequences (hAT, Helitron, Arnoldy, DNA transposons, MuDR and Pogo transposons) in 5′and 3′regulatory regions are color coded as indicated. The numbers indicate the positions on Chromosome 5 (http://gbrowse.arabidopsis.org). Note, Helitron and Arnoldy transposable elements in the pAGL36::GUS promoter region. Plants expressing the transgene were used either as maternal (B) or paternal (C) partners in crosses with wild-type plants. Samples were taken at 3 DAP (left panel) and 6 DAP (right panel). pAGL36::GUS is absent in the seed-coat and only maternally expressed in the endosperm. The pAGL36::GUS signal is increased in 6 DAP versus 3 DAP samples.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3040660&req=5

pgen-1001303-g004: pAGL36::GUS is expressed only from its maternal allele (and only in the fertilization products).(A) A pAGL36::GUS construct was generated using 1752 bp of the promoter region of AGL36 that spans the ATG start codon. Transposable element sequences (hAT, Helitron, Arnoldy, DNA transposons, MuDR and Pogo transposons) in 5′and 3′regulatory regions are color coded as indicated. The numbers indicate the positions on Chromosome 5 (http://gbrowse.arabidopsis.org). Note, Helitron and Arnoldy transposable elements in the pAGL36::GUS promoter region. Plants expressing the transgene were used either as maternal (B) or paternal (C) partners in crosses with wild-type plants. Samples were taken at 3 DAP (left panel) and 6 DAP (right panel). pAGL36::GUS is absent in the seed-coat and only maternally expressed in the endosperm. The pAGL36::GUS signal is increased in 6 DAP versus 3 DAP samples.
Mentions: To rule out that the observed maternal expression is due to expression of AGL36 in the ovule integument, which is a maternal tissue, we generated a reporter construct consisting of 1752 bp of the AGL36 promoter region fused to a GUS reporter (pAGL36::GUS) (Figure 4A). Single-copy lines carrying this construct were used in reciprocal crosses with wild-type Ler and Col plants to examine GUS expression at 3 and 6 DAP. When inherited maternally, pAGL36::GUS expression in the seed was indeed found to be restricted only to the fertilization product (Figure 4B, Figure S7D). In the reciprocal cross, when pAGL36::GUS was inherited from the paternal genome, no GUS expression was detected, (Figure 4C, Figure S7E). Consistent with the SNP analysis, this demonstrated that AGL36 was imprinted and only maternally active throughout its expression cycle. Furthermore, the 1.7 Kb promoter fragment used in this analysis appears to be sufficient to confer parent-of-origin specific expression of the reporter.

Bottom Line: In Arabidopsis, analyses of mutants in the cell-cycle regulator CYCLIN DEPENDENT KINASE A;1 (CKDA;1) have revealed the importance of a paternal genome for the effective development of the endosperm and ultimately the seed.Among those, AGAMOUS-LIKE (AGL) genes encoding Type-I MADS-box transcription factors were significantly overrepresented.Interestingly, our data also show that the active maternal allele of AGL36 is regulated throughout endosperm development by components of the FIS Polycomb Repressive Complex 2 (PRC2), revealing a new type of dual epigenetic regulation in seeds.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biosciences (IMBV), University of Oslo, Oslo, Norway.

ABSTRACT
Seed development in angiosperms is dependent on the interplay among different transcriptional programs operating in the embryo, the endosperm, and the maternally-derived seed coat. In angiosperms, the embryo and the endosperm are products of double fertilization during which the two pollen sperm cells fuse with the egg cell and the central cell of the female gametophyte. In Arabidopsis, analyses of mutants in the cell-cycle regulator CYCLIN DEPENDENT KINASE A;1 (CKDA;1) have revealed the importance of a paternal genome for the effective development of the endosperm and ultimately the seed. Here we have exploited cdka;1 fertilization as a novel tool for the identification of seed regulators and factors involved in parent-of-origin-specific regulation during seed development. We have generated genome-wide transcription profiles of cdka;1 fertilized seeds and identified approximately 600 genes that are downregulated in the absence of a paternal genome. Among those, AGAMOUS-LIKE (AGL) genes encoding Type-I MADS-box transcription factors were significantly overrepresented. Here, AGL36 was chosen for an in-depth study and shown to be imprinted. We demonstrate that AGL36 parent-of-origin-dependent expression is controlled by the activity of METHYLTRANSFERASE1 (MET1) maintenance DNA methyltransferase and DEMETER (DME) DNA glycosylase. Interestingly, our data also show that the active maternal allele of AGL36 is regulated throughout endosperm development by components of the FIS Polycomb Repressive Complex 2 (PRC2), revealing a new type of dual epigenetic regulation in seeds.

Show MeSH
Related in: MedlinePlus