Mitochondrial GFA2 Is Required for Synergid Cell Death in Arabidopsis

Christensen, Cory A.; Gorsich, Steven Ward; Brown, Raymond S.; Jones, Linda G.; Brown, Jessica; Shaw, Janet M.; Drews, Gary N.

doi:10.1105/tpc.002170

Cited by 158 publications

(165 citation statements)

References 93 publications

(120 reference statements)

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“…These mutants include nfd3, nfd4, nfd5, and nfd6 (Table III) identified in this study, as well as the previously reported mutants gfa2 (Christensen et al, 2002) and EDA28 and EDA35 (Pagnussat et al, 2005). Analysis of other nuclear fusion mutants as well as mitochondrial mutants in Arabidopsis and yeast should help to clarify the possible role of the mitochondrion in nuclear fusion in these two organisms.…”

Section: Discussionmentioning

confidence: 99%

“…Expression of GFP and MitoTracker stain was detected as described previously (Christensen et al, 2002), with the modification that roots were mounted in 1 3 Murashige and Skoog salts.…”

Section: Nfd1-gfp Protein Localizationmentioning

confidence: 99%

“…CLSM analysis of ovules was performed as described previously (Christensen et al, 1997(Christensen et al, , 1998(Christensen et al, , 2002) with use of a Zeiss LSM510 microscope as a modification. For analysis of female gametophytes at the terminal developmental stage (stage FG7), we emasculated flowers from heterozygous mutant plants at stage 12c (Christensen et al, 1997), waited 24 to 40 h, and harvested the specimens for fixation.…”

Section: Confocal Analysismentioning

confidence: 99%

“…However, a number of mutants affected in fusion of the polar nuclei during female gametophyte development have been identified, including magatama1 (maa1) and maa3 (Shimizu and Okada, 2000), gametophytic factor2 (gfa2; Christensen et al, 2002), Glc-6-P/phosphate translocator1 (gpt1; Niewiadomski et al, 2005), and EMBRYO SAC DEVELOPMENT ARREST24 (EDA24) to EDA41 (Pagnussat et al, 2005). GFA2 is a J-domain-containing protein similar to yeast Mdj1p, which functions as a chaperone in the mitochondrion (Christensen et al, 2002). GPT1 is required for fatty acid biosynthesis (Niewiadomski et al, 2005).…”

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confidence: 99%

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NUCLEAR FUSION DEFECTIVE1 Encodes the Arabidopsis RPL21M Protein and Is Required for Karyogamy during Female Gametophyte Development and Fertilization

et al. 2006

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Karyogamy, or nuclear fusion, is essential for sexual reproduction. In angiosperms, karyogamy occurs three times: twice during double fertilization of the egg cell and the central cell and once during female gametophyte development when the two polar nuclei fuse to form the diploid central cell nucleus. The molecular mechanisms controlling karyogamy are poorly understood. We have identified nine female gametophyte mutants in Arabidopsis (Arabidopsis thaliana), nuclear fusion defective1 (nfd1) to nfd9, that are defective in fusion of the polar nuclei. In the nfd1 to nfd6 mutants, failure of fusion of the polar nuclei is the only defect detected during megagametogenesis. nfd1 is also affected in karyogamy during double fertilization. Using transmission electron microscopy, we showed that nfd1 nuclei fail to undergo fusion of the outer nuclear membranes. nfd1 contains a T-DNA insertion in RPL21M that is predicted to encode the mitochondrial 50S ribosomal subunit L21, and a wildtype copy of this gene rescues the mutant phenotype. Consistent with the predicted function of this gene, an NFD1-green fluorescent protein fusion protein localizes to mitochondria and the NFD1/RPL21M gene is expressed throughout the plant. The nfd3, nfd4, nfd5, and nfd6 mutants also contain T-DNA insertions in genes predicted to encode proteins that localize to mitochondria, suggesting a role for this organelle in nuclear fusion.

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Section: Discussionmentioning

confidence: 99%

“…Expression of GFP and MitoTracker stain was detected as described previously (Christensen et al, 2002), with the modification that roots were mounted in 1 3 Murashige and Skoog salts.…”

Section: Nfd1-gfp Protein Localizationmentioning

confidence: 99%

Section: Confocal Analysismentioning

confidence: 99%

mentioning

confidence: 99%

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NUCLEAR FUSION DEFECTIVE1 Encodes the Arabidopsis RPL21M Protein and Is Required for Karyogamy during Female Gametophyte Development and Fertilization

et al. 2006

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“…Other mutants with reduced seed size have been reported and can be readily distinguished from iku because they are affected in other aspects of the plant life such as exs (Canales et al, 2002), which causes male sterility; ctr1 (Christensen et al, 2002;F. Berger, personal observations), which prevents cell elongation and ethylene signal transduction (Kieber et al, 1993); and ats (Léon-Kloosterziel et al, 1994), which causes reduction of layers in seed integument.…”

Section: Discussion the Haiku Mutations Affect Endosperm Growth And Mmentioning

confidence: 99%

Arabidopsis haiku Mutants Reveal New Controls of Seed Size by Endosperm

et al. 2003

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In flowering plants, maternal seed integument encloses the embryo and the endosperm, which are both derived from double fertilization. Although the development of these three components must be coordinated, we have limited knowledge of mechanisms involved in such coordination. The endosperm may play a central role in these mechanisms as epigenetic modifications of endosperm development, via imbalance of dosage between maternal and paternal genomes, affecting both the embryo and the integument. To identify targets of such epigenetic controls, we designed a genetic screen in Arabidopsis for mutants that phenocopy the effects of dosage imbalance in the endosperm. The two mutants haiku 1 and haiku 2 produce seed of reduced size that resemble seed with maternal excess in the maternal/paternal dosage. Homozygous haiku seed develop into plants indistinguishable from wild type. Each mutation is sporophytic recessive, and double-mutant analysis suggests that both mutations affect the same genetic pathway. The endosperm of haiku mutants shows a premature arrest of increase in size that causes precocious cellularization of the syncytial endosperm. Reduction of seed size in haiku results from coordinated reduction of endosperm size, embryo proliferation, and cell elongation of the maternally derived integument. We present further evidence for a control of integument development mediated by endosperm-derived signals.In flowering plants, the two female gametes, the egg cell and the central cell, are fertilized by one of the two male gametes delivered by the pollen tube. The zygotic product of the fusion of one male gamete with the egg cell develops into the embryo of the daughter plant. The fertilized central cell develops as the endosperm that nurtures embryo development. In most species, endosperm development is initiated by a proliferative syncytial phase accompanied by cell growth that generates a large multinucleate cell (Olsen, 2001; Berger, 2003). This syncytium is partitioned into individual cells by a specific type of cytokinesis called cellularization. In cereal species, the cellular endosperm stores the reserves of the seed during a phase marked by endoreduplication. Although the endosperm does not store the reserves of the seed in Arabidopsis, it most probably controls the flux of nutrients delivered by the vascular tissue of the mother to the embryo and protects the embryo from physical and osmotic stresses.Because the embryo is surrounded by the endosperm, which, in turn, is enclosed within the ovule integument, these three structures must coordinate their development to produce a mature seed of the appropriate size. The endosperm plays a central role in the control of seed size as indicated by a series of experiments in Arabidopsis and maize (Zea mays), where the dosage balance between maternal and paternal genomes was perturbed (Lin, 1984;Kermicle and Allemand, 1990;Scott et al., 1998). In most flowering plants, the endosperm contains two maternal copies and one paternal copy of the genome (2m/1p). In Arabidop...

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