Cell Differentiation and Morphogenesis Are Uncoupled in Arabidopsis raspberry Embryos.

Yadegari, Ramin; Paiva, G. R. De; Laux, Thomas; Koltunow, Anna M.; Apuya, Nestor R.; Zimmerman, J. Lynn; Fischer, Robert L.; Harada, John J.; Goldberg, Robert B.

doi:10.1105/tpc.6.12.1713

Cited by 191 publications

(144 citation statements)

References 34 publications

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“…2C, iii), mutant embryos (equivalent to approximately 24% to 29% of the total number; Table I) developed to the globular stage (Fig. 2C, vii), but began to take on an abnormal, raspberry-like appearance, with protuberances on the surface of the embryo proper (Yadegari et al, 1994;Apuya et al, 2002). By the time the normal embryos had reached the torpedo stage (Fig.…”

Section: Homozygous Oep80-1 Embryos Arrest At the Globular Stagementioning

confidence: 99%

“…The protuberances on the surface of the embryo proper, responsible for the raspberry-like appearance of the oep80 and tic110 mutant embryos, are in fact a characteristic feature of many mutants that arrest during this stage of embryogenesis. It is thought that they are caused by cellular maturation processes that normally occur during late embryogenesis and continue to proceed in the mutants in spite of the block in embryo growth and morphogenesis (Yadegari et al, 1994;Apuya et al, 2002). Unlike oep80, the tic110 mutation was also associated with abnormal, asymmetric, or unsynchronized cell divisions at earlier developmental stages in some embryos (Kovacheva et al, 2005).…”

Section: Homozygous Oep80-1 Embryos Arrest At the Globular Stagementioning

confidence: 99%

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The Omp85-Related Chloroplast Outer Envelope Protein OEP80 Is Essential for Viability in Arabidopsis

et al. 2008

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b-Barrel proteins of the Omp85 (Outer membrane protein, 85 kD) superfamily exist in the outer membranes of Gram-negative bacteria, mitochondria, and chloroplasts. Prominent Omp85 proteins in bacteria and mitochondria mediate biogenesis of other b-barrel proteins and are indispensable for viability. In Arabidopsis (Arabidopsis thaliana) chloroplasts, there are two distinct types of Omp85-related protein: Toc75 (Translocon at the outer envelope membrane of chloroplasts, 75 kD) and OEP80 (Outer Envelope Protein, 80 kD). Toc75 functions as a preprotein translocation channel during chloroplast import, but the role of OEP80 remains elusive. We characterized three T-DNA mutants of the Arabidopsis OEP80 (AtOEP80) gene. Selectable markers associated with the oep80-1 and oep80-2 insertions segregated abnormally, suggesting embryo lethality of the homozygous genotypes. Indeed, no homozygotes were identified among .100 individuals, and heterozygotes of both mutants produced approximately 25% aborted seeds upon self-pollination. Embryo arrest occurred at a relatively late stage (globular embryo proper) as revealed by analysis using Nomarski optics microscopy. This is substantially later than arrest caused by loss of the principal Toc75 isoform, atToc75-III (two-cell stage), suggesting a more specialized role for AtOEP80. Surprisingly, the oep80-3 T-DNA (located in exon 1 between the first and second ATG codons of the open reading frame) did not cause any detectable developmental defects or affect the size of the AtOEP80 protein in chloroplasts. This indicates that the N-terminal region of AtOEP80 is not essential for the targeting, biogenesis, or functionality of the protein, in contrast with atToc75-III, which requires a bipartite targeting sequence.

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Section: Homozygous Oep80-1 Embryos Arrest At the Globular Stagementioning

confidence: 99%

Section: Homozygous Oep80-1 Embryos Arrest At the Globular Stagementioning

confidence: 99%

The Omp85-Related Chloroplast Outer Envelope Protein OEP80 Is Essential for Viability in Arabidopsis

et al. 2008

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“…Embryo GUS staining was performed as described (Yadegari et al, 1994) with the following modification. Siliques were opened longitudinally and then incubated with GUS staining solution at 37°C overnight.…”

Section: Analysis Of Gus Activitymentioning

confidence: 99%

Functional Characterization of the GATA Transcription Factors GNC and CGA1 Reveals Their Key Role in Chloroplast Development, Growth, and Division in Arabidopsis

et al. 2012

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Chloroplasts develop from proplastids in a process that requires the interplay of nuclear and chloroplast genomes, but key steps in this developmental process have yet to be elucidated. Here, we show that the nucleus-localized transcription factors GATA NITRATE-INDUCIBLE CARBON-METABOLISM-INVOLVED (GNC) and CYTOKININ-RESPONSIVE GATA1 (CGA1) regulate chloroplast development, growth, and division in Arabidopsis (Arabidopsis thaliana). GNC and CGA1 are highly expressed in green tissues, and the phytohormone cytokinin regulates their expression. A gnc cga1 mutant exhibits a reduction in overall chlorophyll levels as well as in chloroplast size in the hypocotyl. Ectopic overexpression of either GNC or CGA1 promotes chloroplast biogenesis in hypocotyl cortex and root pericycle cells, based on increases in the number and size of the chloroplasts, and also results in expanded zones of chloroplast production into the epidermis of hypocotyls and cotyledons and into the cortex of roots. Ectopic overexpression also promotes the development of etioplasts from proplastids in dark-grown seedlings, subsequently enhancing the deetiolation process. Inducible expression of GNC demonstrates that GNCmediated chloroplast biogenesis can be regulated postembryonically, notably so for chloroplast production in cotyledon epidermal cells. Analysis of the gnc cga1 loss-of-function and overexpression lines supports a role for these transcription factors in regulating the effects of cytokinin on chloroplast division. These data support a model in which GNC and CGA1 serve as two of the master transcriptional regulators of chloroplast biogenesis, acting downstream of cytokinin and mediating the development of chloroplasts from proplastids and enhancing chloroplast growth and division in specific tissues.

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“…For examination of embryo phenotypes, tissues were cleared as previously described (Yadegari et al 1994). Samples were visualized using Nomarsky differential interference contrast optics on a Leica DMRX E microscope (Leica Microsystems).…”

Section: Microscopymentioning

confidence: 99%

Characterization of EMU, the Arabidopsis homolog of the yeast THO complex member HPR1

Furumizu¹,

Tsukaya²,

Komeda³

2010

RNA

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Diverse and precise control is essential for eukaryotic gene expression. This is accomplished through the recruitment of a myriad of proteins to a nascent messenger RNA (mRNA) to mediate modifications, such as capping, splicing, 39-end processing, and export. Despite being important for every cell, however, the mechanism by which the formation of diverse messenger ribonucleoprotein (mRNP) particles contributes to maintaining intricate systems in the multicellular organism remains incompletely defined. We identified and characterized a mutant gene named erecta mRNA under-expressed (emu) that leads to the defective mRNA accumulation of ERECTA, a developmental regulator in the model plant Arabidopsis thaliana. EMU encodes a protein homologous to a component of the THO complex that is required for the generation of functional mRNPs. Further analysis suggested that EMU is genetically associated with SERRATE, HYPONASTIC LEAVES1, and ARGONAUTE1, which are required for proper RNA maturation or action. Furthermore, mutations in another THO-related gene led to embryonic lethality. These findings support the presence and importance of the THO-related complex in plants as well as yeast and vertebrates.

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Cell Differentiation and Morphogenesis Are Uncoupled in Arabidopsis raspberry Embryos.

Cited by 191 publications

References 34 publications

The Omp85-Related Chloroplast Outer Envelope Protein OEP80 Is Essential for Viability in Arabidopsis

The Omp85-Related Chloroplast Outer Envelope Protein OEP80 Is Essential for Viability in Arabidopsis

Functional Characterization of the GATA Transcription Factors GNC and CGA1 Reveals Their Key Role in Chloroplast Development, Growth, and Division in Arabidopsis

Characterization of EMU, the Arabidopsis homolog of the yeast THO complex member HPR1

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