The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Masao Tasaka - One of the best experts on this subject based on the ideXlab platform.
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macchi bou 2 is required for early embryo patterning and Cotyledon organogenesis in arabidopsis
Plant and Cell Physiology, 2011Co-Authors: Takako Sono, Masao Tasaka, Masahiko FurutaniAbstract:The phytohormone auxin is a key regulator of organogenesis in plants and is distributed asymmetrically via polar transport. However, the precise mechanisms underlying auxin-mediated organogenesis remain elusive. Here, we have analyzed the macchi-bou 2 (mab2) mutant identified in a pinoid (pid) enhancer mutant screen. Seedlings homozygous for either mab2 or pid showed only mild phenotypic effects on Cotyledon positions and/or numbers. In contrast, mab2 pid double mutant seedlings completely lacked Cotyledons, indicating a synergistic interaction. We found that mab2 homozygous embryos had defective patterns of cell division and showed aberrant Cotyledon organogenesis. Further analysis revealed that the mab2 mutation affected auxin response but not auxin transport in the embryos, suggesting the involvement of MAB2 in auxin response during embryogenesis. MAB2 encodes an Arabidopsis ortholog of MED13, a putative regulatory module component of the Mediator complex. Mediator is a multicomponent complex that is evolutionarily conserved in eukaryotes and its regulatory module associates with Mediator to control the interaction of Mediator and RNA polymerase II. MAB2 interacts with a regulatory module component in yeast cells. Taken together, our data suggest that MAB2 plays a crucial role in embryo patterning and Cotyledon organogenesis, possibly through modulating expression of specific genes such as auxin-responsive genes.
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the nac domain mediates functional specificity of cup shaped Cotyledon proteins
Plant Journal, 2004Co-Authors: Kenichiro Taoka, Mitsuhiro Aida, Yoshiko Yanagimoto, Yasufumi Daimon, Kenichiro Hibara, Masao TasakaAbstract:SummaryIn higher plants, although several genes involved in shoot apical meristem (SAM) formation and organseparation have been isolated, the molecular mechanisms by which they function are largely unknown. CUP-SHAPED Cotyledon (CUC) 1 and CUC2 are examples of two such genes that encode the NAC domainproteins. This study investigated the molecular basis for their activities. Nuclear localization assays indicatedthat green fluorescent protein (GFP)-CUC proteins accumulate in the nucleus. Yeast one-hybrid and transientexpression assays demonstrated that the C-terminal domain (CTD) of the CUC has transactivation activity.Domain-swapping experiments revealed that the functional specificity of the CUC for promoting adventitiousshoot formation resides in the highly conserved NAC domain, not in the CTD in which motifs specific to theCUC subfamily are located. Taken together, these observations suggest that CUC proteins transactivate thetarget genes involved in SAM formation and organ separation through a specific interaction between the NACdomain and the promoter region of the target genes.Keywords: CUC, NAC, transcription factor, shoot apical meristem, adventitious shoot, Arabidopsis.IntroductionInhigherplants,mostoftheaerialpartsarederivedfromtheshoot apical meristem (SAM). SAM of dicots is generatedbetween two Cotyledon primordia during embryogenesis.SAM formation can be induced in differentiated organs orcalli in vitro.InArabidopsis, several genes involved in SAMformation have been identified, including the CUP-SHAPEDCotyledon (CUC) 1, CUC2 and CUC3. Seedlings of thecuc1 cuc2 double mutant completely lack an embryonicSAM, and two Cotyledons are fused along both edges toform one cup-shaped structure (Aida et al., 1997). In addi-tion, calli derived from the hypocotyls of the cuc1 cuc2double mutant are less competent in forming adventitiousshoots (Aida et al., 1997; Daimon et al., 2003). Expression ofthese genes is observed in the presumptive SAM at theglobular stage during embryogenesis and later as a stripe atthe apex of the mature embryo between two Cotyledonprimordia (Aida et al., 1999; Takada et al., 2001). Ectopicexpression of the CUC1 gene causes ectopic meristem for-mation on Cotyledons (Hibara et al., 2003; Takada et al.,2001), and overexpression of either the CUC1 or the CUC2gene in the callus promotes adventitious shoot formation(Daimon et al., 2003). CUC3 was identified from analyses ofan enhancer trap line showing restricted GUS expression ina region containing the embryonic SAM (Vroemen et al.,2003).ExpressionofCUC3isdetectedintheapicalhalfoftheembryo at the octant stage during embryogenesis and laterthe expression becomes restricted to the boundariesbetween the SAM and the Cotyledons and the boundaries ofthe Cotyledon margins in mature embryos (Vroemen et al.,2003). Reduced CUC3 expression causes an increase in thefrequency of fused Cotyledon in cuc1 and/or cuc2 mutantbackgrounds (Vroemen et al., 2003). These results stronglysuggest that the CUC1, CUC2, and CUC3 genes haveredundant function and are essential for embryonic SAMformation. However, the molecular function of the CUCproteins is still unknown.Sequence analysis revealed that the CUC1, CUC2 andCUC3 genes encode the NAC domain proteins (Aida et al.,1997; Takada et al., 2001; Vroemen et al., 2003). Some NACdomain proteins have the capacity to bind DNA and/or
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pin formed1 and pinoid regulate boundary formation and Cotyledon development in arabidopsis embryogenesis
Development, 2004Co-Authors: Masahiko Furutani, Teva Vernoux, Jan Traas, Takehide Kato, Masao Tasaka, Mitsuhiro AidaAbstract:In diCotyledonous plants, two Cotyledons are formed at bilaterally symmetric positions in the apical region of the embryo. Single mutations in the PIN-FORMED1 ( PIN1 ) and PINOID ( PID ) genes, which mediate auxin-dependent organ formation, moderately disrupt the symmetric patterning of Cotyledons. We report that the pin1 pid double mutant displays a striking phenotype that completely lacks Cotyledons and bilateral symmetry. In the double mutant embryo, the expression domains of CUP-SHAPED Cotyledon1 ( CUC1 ), CUC2 and SHOOT MERISTEMLESS ( STM ), the functions of which are normally required to repress growth at Cotyledon boundaries, expand to the periphery and overlap with a Cotyledon-specific marker, FILAMENTOUS FLOWER . Elimination of CUC1, CUC2 or STM activity leads to recovery of Cotyledon growth in the double mutant, suggesting that the negative regulation of these boundary genes by PIN1 and PID is sufficient for primordium growth. We also show that PID mRNA is localized mainly to the boundaries of Cotyledon primordia and early expression of PID mRNA is dependent on PIN1 . Our results demonstrate the redundant roles of PIN1 and PID in the establishment of bilateral symmetry, as well as in the promotion of Cotyledon outgrowth, the latter of which involves the negative regulation of CUC1, CUC2 and STM genes, which are boundary-specific downstream effectors.
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shoot apical meristem and Cotyledon formation during arabidopsis embryogenesis interaction among the cup shaped Cotyledon and shoot meristemless genes
Development, 1999Co-Authors: Mitsuhiro Aida, Tetsuya Ishida, Masao TasakaAbstract:The shoot apical meristem and Cotyledons of higher plants are established during embryogenesis in the apex. Redundant CUP-SHAPED Cotyledon 1 (CUC1) and CUC2 as well as SHOOT MERISTEMLESS (STM) of Arabidopsis are required for shoot apical meristem formation and Cotyledon separation. To elucidate how the apical region of the embryo is established, we investigated genetic interactions among CUC1, CUC2 and STM, as well as the expression patterns of CUC2 and STM mRNA. Expression of these genes marked the incipient shoot apical meristem as well as the boundaries of Cotyledon primordia, consistent with their roles for shoot apical meristem formation and Cotyledon separation. Genetic and expression analyses indicate that CUC1 and CUC2 are redundantly required for expression of STM to form the shoot apical meristem, and that STM is required for proper spatial expression of CUC2 to separate Cotyledons. A model for pattern formation in the apical region of the Arabidopsis embryo is presented.
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genes involved in organ separation in arabidopsis an analysis of the cup shaped Cotyledon mutant
The Plant Cell, 1997Co-Authors: M Aida, Tetsuya Ishida, H Fukaki, Hisao Fujisawa, Masao TasakaAbstract:Mutations in CUC1 and CUC2 (for CUP-SHAPED Cotyledon), which are newly identified genes of Arabidopsis, caused defects in the separation of Cotyledons (embryonic organs), sepals, and stamens (floral organs) as well as in the formation of shoot apical meristems. These defects were most apparent in the double mutant. Phenotypes of the mutants suggest a common mechanism for separating adjacent organs within the same whorl in both embryos and flowers. We cloned the CUC2 gene and found that the encoded protein was homologous to the petunia NO APICAL MERISTEM (NAM) protein, which is thought to act in the development of embryos and flowers.
Klaus Apel - One of the best experts on this subject based on the ideXlab platform.
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snowy Cotyledon 2 the identification of a zinc finger domain protein essential for chloroplast development in Cotyledons but not in true leaves
Plant Molecular Biology, 2008Co-Authors: Veronica Albrecht, Anke Ingenfeld, Klaus ApelAbstract:In Cotyledons of etiolated seedlings light-dependent transformation of etioplasts to chloroplasts marks the transition from heterotrophic to autotrophic growth. Genetic factors required for this developmental step were identified by isolating mutants of Arabidopsis thaliana that were impaired in chloroplast development in Cotyledons but not in true leaves. Several mutants with chlorophyll-deficient Cotyledons were isolated and dubbed snowy Cotyledon (sco). Here we describe the identification and detailed characterization of the snowy Cotyledon 2 mutant. The mutated SCO2 gene was identified using a map-based cloning strategy. SCO2 was shown to encode a novel protein which contains a single DnaJ-like zinc finger domain. The SCO2 protein fused to GFP was shown to be present in chloroplasts. Inactivation of SCO2 has almost no detectable impact on the levels of transcripts encoding plastid-specific proteins but leads to a significant reduction of plastid protein levels. Even though transcripts of SCO2 have been found ubiquitously in green tissues as well as in roots phenotypic changes due to SCO2 inactivation are confined to Cotyledons. The Cotyledons in embryos of sco2 are unaffected in their chloroplast biogenesis. Upon precocious germination seedlings of sco2 and wild type are indistinguishable. The SCO2 mutation affects chloroplast biogenesis only at the end of dormancy during seed germination. The transition from heterotrophic to autotrophic growth is dramatically impaired in sco2 when seedlings were kept in the dark for more than 5 days prior to light exposure.
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characterization of the snowy Cotyledon 1 mutant of arabidopsis thaliana the impact of chloroplast elongation factor g on chloroplast development and plant vitality
Plant Molecular Biology, 2006Co-Authors: Veronica Albrecht, Anke Ingenfeld, Klaus ApelAbstract:During seedling development chloroplast formation marks the transition from heterotrophic to autotrophic growth. The development and activity of chloroplasts may differ in Cotyledons that initially serve as a storage organ and true leaves whose primary function is photosynthesis. A genetic screen was used for the identification of genes that affect selectively chloroplast function in Cotyledons of Arabidopsis thaliana. Several mutants exhibiting pale Cotyledons and green true leaves were isolated and dubbed snowy Cotyledon (sco).One of the mutants, sco1, was characterized in more detail. The mutated gene was identified using map-based cloning. The mutant contains a point mutation in a gene encoding the chloroplast elongation factor G, leading to an amino acid exchange within the predicted 70S ribosome-binding domain. The mutation results in a delay in the onset of germination. At this early developmental stage embryos still contain undifferentiated proplastids, whose proper function seems necessary for seed germination. In light-grown sco1 seedlings the greening of Cotyledons is severely impaired, whereas the following true leaves develop normally as in wild-type plants. Despite this apparent similarity of chloroplast development in true leaves of mutant and wild-type plants various aspects of mature plant development are also affected by the sco1 mutation such as the onset of flowering, the growth rate, and seed production. The onset of senescence in the mutant and the wild-type plants occurs, however, at the same time, suggesting that in the mutant this particular developmental step does not seem to suffer from reduced protein translation efficiency in chloroplasts.
Dario Leister - One of the best experts on this subject based on the ideXlab platform.
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snowy Cotyledon 2 promotes chloroplast development and has a role in leaf variegation in both lotus japonicus and arabidopsis thaliana
Molecular Plant, 2017Co-Authors: Nicola Zagari, Omar Sandovalibanez, Niels Sandal, Junyi Su, Manuel Rodriguezconcepcion, Jens Stougaard, Mathias Pribil, Dario LeisterAbstract:Abstract Plants contain various factors that transiently interact with subunits or intermediates of the thylakoid multiprotein complexes, promoting their stable association and integration. Hence, assembly factors are essential for chloroplast development and the transition from heterotrophic to phototrophic growth. Snowy Cotyledon 2 (SCO2) is a DNAJ-like protein involved in thylakoid membrane biogenesis and interacts with the light-harvesting chlorophyll-binding protein LHCB1. In Arabidopsis thaliana , SCO2 function was previously reported to be restricted to Cotyledons. Here we show that disruption of SCO2 in Lotus japonicus results not only in paler Cotyledons but also in variegated true leaves. Furthermore, smaller and pale-green true leaves can also be observed in A. thaliana sco2 ( atsco2 ) mutants under short-day conditions. In both species, SCO2 is required for proper accumulation of PSII–LHCII complexes. In contrast to other variegated mutants, inhibition of chloroplastic translation strongly affects L. japonicus sco2 mutant development and fails to suppress their variegated phenotype. Moreover, inactivation of the suppressor of variegation AtClpR1 in the atsco2 background results in an additive double-mutant phenotype with variegated true leaves. Taken together, our results indicate that SCO2 plays a distinct role in PSII assembly or repair and constitutes a novel factor involved in leaf variegation.
Veronica Albrecht - One of the best experts on this subject based on the ideXlab platform.
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snowy Cotyledon 2 the identification of a zinc finger domain protein essential for chloroplast development in Cotyledons but not in true leaves
Plant Molecular Biology, 2008Co-Authors: Veronica Albrecht, Anke Ingenfeld, Klaus ApelAbstract:In Cotyledons of etiolated seedlings light-dependent transformation of etioplasts to chloroplasts marks the transition from heterotrophic to autotrophic growth. Genetic factors required for this developmental step were identified by isolating mutants of Arabidopsis thaliana that were impaired in chloroplast development in Cotyledons but not in true leaves. Several mutants with chlorophyll-deficient Cotyledons were isolated and dubbed snowy Cotyledon (sco). Here we describe the identification and detailed characterization of the snowy Cotyledon 2 mutant. The mutated SCO2 gene was identified using a map-based cloning strategy. SCO2 was shown to encode a novel protein which contains a single DnaJ-like zinc finger domain. The SCO2 protein fused to GFP was shown to be present in chloroplasts. Inactivation of SCO2 has almost no detectable impact on the levels of transcripts encoding plastid-specific proteins but leads to a significant reduction of plastid protein levels. Even though transcripts of SCO2 have been found ubiquitously in green tissues as well as in roots phenotypic changes due to SCO2 inactivation are confined to Cotyledons. The Cotyledons in embryos of sco2 are unaffected in their chloroplast biogenesis. Upon precocious germination seedlings of sco2 and wild type are indistinguishable. The SCO2 mutation affects chloroplast biogenesis only at the end of dormancy during seed germination. The transition from heterotrophic to autotrophic growth is dramatically impaired in sco2 when seedlings were kept in the dark for more than 5 days prior to light exposure.
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characterization of the snowy Cotyledon 1 mutant of arabidopsis thaliana the impact of chloroplast elongation factor g on chloroplast development and plant vitality
Plant Molecular Biology, 2006Co-Authors: Veronica Albrecht, Anke Ingenfeld, Klaus ApelAbstract:During seedling development chloroplast formation marks the transition from heterotrophic to autotrophic growth. The development and activity of chloroplasts may differ in Cotyledons that initially serve as a storage organ and true leaves whose primary function is photosynthesis. A genetic screen was used for the identification of genes that affect selectively chloroplast function in Cotyledons of Arabidopsis thaliana. Several mutants exhibiting pale Cotyledons and green true leaves were isolated and dubbed snowy Cotyledon (sco).One of the mutants, sco1, was characterized in more detail. The mutated gene was identified using map-based cloning. The mutant contains a point mutation in a gene encoding the chloroplast elongation factor G, leading to an amino acid exchange within the predicted 70S ribosome-binding domain. The mutation results in a delay in the onset of germination. At this early developmental stage embryos still contain undifferentiated proplastids, whose proper function seems necessary for seed germination. In light-grown sco1 seedlings the greening of Cotyledons is severely impaired, whereas the following true leaves develop normally as in wild-type plants. Despite this apparent similarity of chloroplast development in true leaves of mutant and wild-type plants various aspects of mature plant development are also affected by the sco1 mutation such as the onset of flowering, the growth rate, and seed production. The onset of senescence in the mutant and the wild-type plants occurs, however, at the same time, suggesting that in the mutant this particular developmental step does not seem to suffer from reduced protein translation efficiency in chloroplasts.
Mitsuhiro Aida - One of the best experts on this subject based on the ideXlab platform.
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the nac domain mediates functional specificity of cup shaped Cotyledon proteins
Plant Journal, 2004Co-Authors: Kenichiro Taoka, Mitsuhiro Aida, Yoshiko Yanagimoto, Yasufumi Daimon, Kenichiro Hibara, Masao TasakaAbstract:SummaryIn higher plants, although several genes involved in shoot apical meristem (SAM) formation and organseparation have been isolated, the molecular mechanisms by which they function are largely unknown. CUP-SHAPED Cotyledon (CUC) 1 and CUC2 are examples of two such genes that encode the NAC domainproteins. This study investigated the molecular basis for their activities. Nuclear localization assays indicatedthat green fluorescent protein (GFP)-CUC proteins accumulate in the nucleus. Yeast one-hybrid and transientexpression assays demonstrated that the C-terminal domain (CTD) of the CUC has transactivation activity.Domain-swapping experiments revealed that the functional specificity of the CUC for promoting adventitiousshoot formation resides in the highly conserved NAC domain, not in the CTD in which motifs specific to theCUC subfamily are located. Taken together, these observations suggest that CUC proteins transactivate thetarget genes involved in SAM formation and organ separation through a specific interaction between the NACdomain and the promoter region of the target genes.Keywords: CUC, NAC, transcription factor, shoot apical meristem, adventitious shoot, Arabidopsis.IntroductionInhigherplants,mostoftheaerialpartsarederivedfromtheshoot apical meristem (SAM). SAM of dicots is generatedbetween two Cotyledon primordia during embryogenesis.SAM formation can be induced in differentiated organs orcalli in vitro.InArabidopsis, several genes involved in SAMformation have been identified, including the CUP-SHAPEDCotyledon (CUC) 1, CUC2 and CUC3. Seedlings of thecuc1 cuc2 double mutant completely lack an embryonicSAM, and two Cotyledons are fused along both edges toform one cup-shaped structure (Aida et al., 1997). In addi-tion, calli derived from the hypocotyls of the cuc1 cuc2double mutant are less competent in forming adventitiousshoots (Aida et al., 1997; Daimon et al., 2003). Expression ofthese genes is observed in the presumptive SAM at theglobular stage during embryogenesis and later as a stripe atthe apex of the mature embryo between two Cotyledonprimordia (Aida et al., 1999; Takada et al., 2001). Ectopicexpression of the CUC1 gene causes ectopic meristem for-mation on Cotyledons (Hibara et al., 2003; Takada et al.,2001), and overexpression of either the CUC1 or the CUC2gene in the callus promotes adventitious shoot formation(Daimon et al., 2003). CUC3 was identified from analyses ofan enhancer trap line showing restricted GUS expression ina region containing the embryonic SAM (Vroemen et al.,2003).ExpressionofCUC3isdetectedintheapicalhalfoftheembryo at the octant stage during embryogenesis and laterthe expression becomes restricted to the boundariesbetween the SAM and the Cotyledons and the boundaries ofthe Cotyledon margins in mature embryos (Vroemen et al.,2003). Reduced CUC3 expression causes an increase in thefrequency of fused Cotyledon in cuc1 and/or cuc2 mutantbackgrounds (Vroemen et al., 2003). These results stronglysuggest that the CUC1, CUC2, and CUC3 genes haveredundant function and are essential for embryonic SAMformation. However, the molecular function of the CUCproteins is still unknown.Sequence analysis revealed that the CUC1, CUC2 andCUC3 genes encode the NAC domain proteins (Aida et al.,1997; Takada et al., 2001; Vroemen et al., 2003). Some NACdomain proteins have the capacity to bind DNA and/or
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pin formed1 and pinoid regulate boundary formation and Cotyledon development in arabidopsis embryogenesis
Development, 2004Co-Authors: Masahiko Furutani, Teva Vernoux, Jan Traas, Takehide Kato, Masao Tasaka, Mitsuhiro AidaAbstract:In diCotyledonous plants, two Cotyledons are formed at bilaterally symmetric positions in the apical region of the embryo. Single mutations in the PIN-FORMED1 ( PIN1 ) and PINOID ( PID ) genes, which mediate auxin-dependent organ formation, moderately disrupt the symmetric patterning of Cotyledons. We report that the pin1 pid double mutant displays a striking phenotype that completely lacks Cotyledons and bilateral symmetry. In the double mutant embryo, the expression domains of CUP-SHAPED Cotyledon1 ( CUC1 ), CUC2 and SHOOT MERISTEMLESS ( STM ), the functions of which are normally required to repress growth at Cotyledon boundaries, expand to the periphery and overlap with a Cotyledon-specific marker, FILAMENTOUS FLOWER . Elimination of CUC1, CUC2 or STM activity leads to recovery of Cotyledon growth in the double mutant, suggesting that the negative regulation of these boundary genes by PIN1 and PID is sufficient for primordium growth. We also show that PID mRNA is localized mainly to the boundaries of Cotyledon primordia and early expression of PID mRNA is dependent on PIN1 . Our results demonstrate the redundant roles of PIN1 and PID in the establishment of bilateral symmetry, as well as in the promotion of Cotyledon outgrowth, the latter of which involves the negative regulation of CUC1, CUC2 and STM genes, which are boundary-specific downstream effectors.
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shoot apical meristem and Cotyledon formation during arabidopsis embryogenesis interaction among the cup shaped Cotyledon and shoot meristemless genes
Development, 1999Co-Authors: Mitsuhiro Aida, Tetsuya Ishida, Masao TasakaAbstract:The shoot apical meristem and Cotyledons of higher plants are established during embryogenesis in the apex. Redundant CUP-SHAPED Cotyledon 1 (CUC1) and CUC2 as well as SHOOT MERISTEMLESS (STM) of Arabidopsis are required for shoot apical meristem formation and Cotyledon separation. To elucidate how the apical region of the embryo is established, we investigated genetic interactions among CUC1, CUC2 and STM, as well as the expression patterns of CUC2 and STM mRNA. Expression of these genes marked the incipient shoot apical meristem as well as the boundaries of Cotyledon primordia, consistent with their roles for shoot apical meristem formation and Cotyledon separation. Genetic and expression analyses indicate that CUC1 and CUC2 are redundantly required for expression of STM to form the shoot apical meristem, and that STM is required for proper spatial expression of CUC2 to separate Cotyledons. A model for pattern formation in the apical region of the Arabidopsis embryo is presented.
