A Classical Arabinogalactan Protein Is Essential for the Initiation of Female Gametogenesis in Arabidopsis

Acosta-García, Gerardo; Vielle‐Calzada, Jean‐Philippe

doi:10.1105/tpc.104.024588

Cited by 162 publications

(105 citation statements)

References 93 publications

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“…For whole-mount observations, individual gynoecia were dissected longitudinally by using hypodermic needles (1-ml insulin syringes, Becton Dickinson) and processed as described in ref. 32. ␤-Glucuronidase (GUS) staining assays were conducted as described in ref.…”

Section: Methodsmentioning

confidence: 99%

CHR11, a chromatin-remodeling factor essential for nuclear proliferation during female gametogenesis in Arabidopsis thaliana

Huanca‐Mamani¹,

García-Aguilar²,

León-Martínez³

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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111

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Chromatin-remodeling factors regulate the establishment of transcriptional programs during plant development. Although 42 genes encoding members of the SWI2͞SNF2 family have been identified in Arabidopsis thaliana, <10 have been assigned a precise function on the basis of a mutant phenotype, and none have been shown to play a specific role during the gametophytic phase of the plant life cycle. A. thaliana chromatin-remodeling protein 11 (CHR11) encodes an imitation of switch (ISWI)-like chromatin-remodeling protein abundantly expressed during female gametogenesis and embryogenesis in Arabidopsis. To determine the function of CHR11 in wild-type plants, we introduced a hairpin construct leading to the production of double-stranded RNA, which specifically degraded the endogenous CHR11 mRNA by RNA interference (RNAi). Transcription of the RNAi-inducing hairpin RNA was driven by either a constitutive cauliflower mosaic virus 35S promoter (CaMV35S) acting at most stages of the sporophytic phase or a newly identified specific promoter acting at the onset of the female gametophytic phase (pFM1). All adult transformants that constitutively lacked sporophytic CHR11 activity showed reduced plant height and small cotyledonary embryos with limited cell expansion. In contrast, RNAi lines in which CHR11 was specifically silenced at the onset of female gametogenesis (megagametogenesis) had normal height and embryo size but had defective female gametophytes arrested before the completion of the mitotic haploid nuclear divisions. These results show that CHR11 is essential for haploid nuclear proliferation during megagametogenesis and cell expansion during the sporophytic phase, demonstrating the functional versatility of SWI2͞SNF2 chromatinremodeling factors during both generations of the plant life cycle.imitation of switch proteins ͉ megagametophyte ͉ RNA interference ͉ seed development ͉ functional megaspore T he accessibility of DNA to transcription factors or other types of interacting molecules is regulated by enzymatic complexes that modify nucleosomal structure by means of ATP-dependent chromatin-remodeling or histone modification (1). ATPdependent chromatin-remodeling factors are multisubunit complexes that alter the chromatin structure by changing the conformational state of the nucleosome. These structural changes are accomplished without covalent modification and can be involved in either the activation or the repression of transcription (2). Members of the SWI2͞SNF2 family of ATP-dependent proteins share an ATPase domain that is essential for their chromatin-remodeling activity. In addition, SWI2͞SNF2 proteins have a large variety of Nand C-terminal domains that are often involved in their interaction with other members of specific chromatin-associated complexes. The largest eukaryotic group of SWI2͞SNF2, ATP-dependent, chromatin-remodeling proteins is the imitation of switch (ISWI) subfamily. Originally identified in Drosophila (3, 4), ISWI members are distinguished from other SWI2͞SNF2 proteins by the presence of t...

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Section: Methodsmentioning

confidence: 99%

CHR11, a chromatin-remodeling factor essential for nuclear proliferation during female gametogenesis in Arabidopsis thaliana

Huanca‐Mamani¹,

García-Aguilar²,

León-Martínez³

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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111

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“…The functional megaspore is an appropriate control for such experiments because its development requires de novo transcription of developmentally regulated genes. For example, AGP18, an arabinogalactan protein, is necessary for the early development of the female gametophyte and is specifically expressed in the differentiating megaspore (Acosta-Garcia and Vielle-Calzada, 2004). Heterozygous loss-of-function mutants for the AGP18 locus segregate as gametophytic lethal, with half of the gametophytes aborted in the ovules.…”

Section: Embryo and Endosperm Have Different Transcriptional Requiremmentioning

confidence: 99%

Embryo and Endosperm Inherit Distinct Chromatin and Transcriptional States from the Female Gametes in Arabidopsis

et al. 2010

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Whether deposited maternal products are important during early seed development in flowering plants remains controversial. Here, we show that RNA interference-mediated downregulation of transcription is deleterious to endosperm development but does not block zygotic divisions. Furthermore, we show that RNA POLYMERASE II is less active in the embryo than in the endosperm. This dimorphic pattern is established late during female gametogenesis and is inherited by the two products of fertilization. This juxtaposition of distinct transcriptional activities correlates with differential patterns of histone H3 lysine 9 dimethylation, LIKE HETEROCHROMATIN PROTEIN1 localization, and Histone H2B turnover in the egg cell versus the central cell. Thus, distinct epigenetic and transcriptional patterns in the embryo and endosperm are already established in their gametic progenitors. We further demonstrate that the non-CG DNA methyltransferase CHROMOMETHYLASE3 (CMT3) and DEMETER-LIKE DNA glycosylases are required for the correct distribution of H3K9 dimethylation in the egg and central cells, respectively, and that plants defective for CMT3 activity show abnormal embryo development. Our results provide evidence that cell-specific mechanisms lead to the differentiation of epigenetically distinct female gametes in Arabidopsis thaliana. They also suggest that the establishment of a quiescent state in the zygote may play a role in the reprogramming of the young plant embryo.

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“…The PMR6 gene, which encodes a putative pectate lyase, was identified in a genetic screen for mutants with noncompatible interactions with the powdery mildew fungus (Erysiphe cichoracearum) (Vogel et al, 2002). The Arabidopsis classical AGP, AGP18, was shown to be required for female gametophyte development (Acosta-García and Vielle-Calzada, 2004). Overexpression of the tomato (Lycopersicon esculentum) AGP, LeAGP-1, caused reduced plant growth and seed size (Sun et al, 2004a).…”

Section: Introductionmentioning

confidence: 99%

Glycosylphosphatidylinositol-Anchored Proteins Are Required for Cell Wall Synthesis and Morphogenesis in Arabidopsis

et al. 2005

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Mutations at five loci named PEANUT1-5 (PNT) were identified in a genetic screen for radially swollen embryo mutants. pnt1 cell walls showed decreased crystalline cellulose, increased pectins, and irregular and ectopic deposition of pectins, xyloglucans, and callose. Furthermore, pnt1 pollen is less viable than the wild type, and pnt1 embryos were delayed in morphogenesis and showed defects in shoot and root meristems. The PNT1 gene encodes the Arabidopsis thaliana homolog of mammalian PIG-M, an endoplasmic reticulum-localized mannosyltransferase that is required for synthesis of the glycosylphosphatidylinositol (GPI) anchor. All five pnt mutants showed strongly reduced accumulation of GPI-anchored proteins, suggesting that they all have defects in GPI anchor synthesis. Although the mutants are seedling lethal, pnt1 cells are able to proliferate for a limited time as undifferentiated callus and do not show the massive deposition of ectopic cell wall material seen in pnt1 embryos. The different phenotype of pnt1 cells in embryos and callus suggest a differential requirement for GPI-anchored proteins in cell wall synthesis in these two tissues and points to the importance of GPI anchoring in coordinated multicellular growth.

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A Classical Arabinogalactan Protein Is Essential for the Initiation of Female Gametogenesis in Arabidopsis

Cited by 162 publications

References 93 publications

CHR11, a chromatin-remodeling factor essential for nuclear proliferation during female gametogenesis in Arabidopsis thaliana

CHR11, a chromatin-remodeling factor essential for nuclear proliferation during female gametogenesis in Arabidopsis thaliana

Embryo and Endosperm Inherit Distinct Chromatin and Transcriptional States from the Female Gametes in Arabidopsis

Glycosylphosphatidylinositol-Anchored Proteins Are Required for Cell Wall Synthesis and Morphogenesis in Arabidopsis

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