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1.
EMBO J ; 39(9): e103894, 2020 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-32187732

RESUMO

Production of reactive oxygen species (ROS) by NADPH oxidases (NOXs) impacts many processes in animals and plants, and many plant receptor pathways involve rapid, NOX-dependent increases of ROS. Yet, their general reactivity has made it challenging to pinpoint the precise role and immediate molecular action of ROS. A well-understood ROS action in plants is to provide the co-substrate for lignin peroxidases in the cell wall. Lignin can be deposited with exquisite spatial control, but the underlying mechanisms have remained elusive. Here, we establish a kinase signaling relay that exerts direct, spatial control over ROS production and lignification within the cell wall. We show that polar localization of a single kinase component is crucial for pathway function. Our data indicate that an intersection of more broadly localized components allows for micrometer-scale precision of lignification and that this system is triggered through initiation of ROS production as a critical peroxidase co-substrate.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Lignina/metabolismo , Proteínas Quinases/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Regulação da Expressão Gênica de Plantas , NADPH Oxidases/metabolismo , Peroxidases/metabolismo , Raízes de Plantas/metabolismo
2.
PLoS Genet ; 15(4): e1007847, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30998684

RESUMO

The embryonic cuticle is necessary for normal seed development and seedling establishment in Arabidopsis. Although mutants with defective embryonic cuticles have been identified, neither the deposition of cuticle material, nor its regulation, has been described during embryogenesis. Here we use electron microscopy, cuticle staining and permeability assays to show that cuticle deposition initiates de novo in patches on globular embryos. By combining these techniques with genetics and gene expression analysis, we show that successful patch coalescence to form a continuous cuticle requires a signalling involving the endosperm-specific subtilisin protease ALE1 and the receptor kinases GSO1 and GSO2, which are expressed in the developing embryonic epidermis. Transcriptome analysis shows that this pathway regulates stress-related gene expression in seeds. Consistent with these findings we show genetically, and through activity analysis, that the stress-associated MPK6 protein acts downstream of GSO1 and GSO2 in the developing embryo. We propose that a stress-related signalling pathway has been hijacked in some angiosperm seeds through the recruitment of endosperm-specific components. Our work reveals the presence of an inter-compartmental dialogue between the endosperm and embryo that ensures the formation of an intact and functional cuticle around the developing embryo through an "auto-immune" type interaction.


Assuntos
Arabidopsis/embriologia , Arabidopsis/fisiologia , Desenvolvimento Embrionário , Desenvolvimento Vegetal , Transdução de Sinais , Estresse Fisiológico , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Desenvolvimento Embrionário/genética , Endosperma/embriologia , Endosperma/genética , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Proteínas Quinases Ativadas por Mitógeno/genética , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Fenótipo , Desenvolvimento Vegetal/genética , Plantas Geneticamente Modificadas , Sementes/genética , Estresse Fisiológico/genética , Transgenes
3.
Plant Cell ; 29(7): 1642-1656, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28696222

RESUMO

Arabidopsis thaliana seed development requires the concomitant development of two zygotic compartments, the embryo and the endosperm. Following fertilization, the endosperm expands and the embryo grows invasively through the endosperm, which breaks down. Here, we describe a structure we refer to as the embryo sheath that forms on the surface of the embryo as it starts to elongate. The sheath is deposited outside the embryonic cuticle and incorporates endosperm-derived material rich in extensin-like molecules. Sheath production is dependent upon the activity of ZHOUPI, an endosperm-specific transcription factor necessary for endosperm degradation, embryo growth, embryo-endosperm separation, and normal embryo cuticle formation. We show that the peptide KERBEROS, whose expression is ZHOUPI dependent, is necessary both for the formation of a normal embryo sheath and for embryo-endosperm separation. Finally, we show that the receptor-like kinases GSO1 and GSO2 are required for sheath deposition at the embryo surface but not for production of sheath material in the endosperm. We present a model in which sheath formation depends on the coordinated production of material in the endosperm and signaling within the embryo, highlighting the complex molecular interaction between these two tissues during early seed development.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiologia , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Endosperma/fisiologia , Sementes/fisiologia , Proteínas de Arabidopsis/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Endosperma/genética , Epitopos/genética , Epitopos/metabolismo , Regulação da Expressão Gênica de Plantas , Mutação , Plantas Geneticamente Modificadas , Proteínas Quinases/genética , Proteínas Quinases/metabolismo , Sementes/crescimento & desenvolvimento , Serina Endopeptidases/genética , Serina Endopeptidases/metabolismo , Transdução de Sinais/genética
4.
Development ; 143(18): 3300-5, 2016 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-27287798

RESUMO

Seed development in angiosperms demands the tightly coordinated development of three genetically distinct structures. The embryo is surrounded by the endosperm, which is in turn enclosed within the maternally derived seed coat. In Arabidopsis, final seed size is determined by early expansion of the coenocytic endosperm, which then cellularises and subsequently undergoes developmental programmed cell death, breaking down as the embryo grows. Endosperm breakdown requires the endosperm-specific basic helix-loop-helix transcription factor ZHOUPI. However, to date, the mechanism underlying the Arabidopsis endosperm breakdown process has not been elucidated. Here, we provide evidence that ZHOUPI does not induce the developmental programmed cell death of the endosperm directly. Instead ZHOUPI indirectly triggers cell death by regulating the expression of cell wall-modifying enzymes, thus altering the physical properties of the endosperm to condition a mechanical environment permitting the compression of the cellularised endosperm by the developing embryo.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Endosperma/metabolismo , Sementes/metabolismo , Morte Celular/fisiologia , Estresse Mecânico
5.
Development ; 141(6): 1222-7, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24553285

RESUMO

In Arabidopsis seeds, embryo growth is coordinated with endosperm breakdown. Mutants in the endosperm-specific gene ZHOUPI (ZOU), which encodes a unique basic helix-loop-helix (bHLH) transcription factor, have an abnormal endosperm that persists throughout seed development, significantly impeding embryo growth. Here we show that loss of function of the bHLH-encoding gene INDUCER OF CBP EXPRESSION 1 (ICE1) causes an identical endosperm persistence phenotype. We show that ZOU and ICE1 are co-expressed in the endosperm and interact in yeast via their bHLH domains. We show both genetically and in a heterologous plant system that, despite the fact that both ZOU and ICE1 can form homodimers in yeast, their role in endosperm breakdown requires their heterodimerization. Consistent with this conclusion, we confirm that ZOU and ICE1 regulate the expression of common target genes in the developing endosperm. Finally, we show that heterodimerization of ZOU and ICE1 is likely to be necessary for their binding to specific targets, rather than for their nuclear localization in the endosperm. By comparing our results with paradigms of bHLH function and evolution in animal systems we propose that the ZOU/ICE1 complex might have ancient origins, acquiring novel megagametophyte-specific functions in heterosporous land plants that were conserved in the angiosperm endosperm.


Assuntos
Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/metabolismo , Arabidopsis/embriologia , Arabidopsis/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/química , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Fatores de Transcrição/química , Fatores de Transcrição/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Endosperma/embriologia , Endosperma/genética , Endosperma/metabolismo , Evolução Molecular , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Hibridização In Situ , Mutação , Plantas Geneticamente Modificadas , Domínios e Motivos de Interação entre Proteínas , Multimerização Proteica , Fatores de Transcrição/genética , Técnicas do Sistema de Duplo-Híbrido
6.
Plant J ; 84(3): 574-86, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26361885

RESUMO

In angiosperm seeds the embryo is embedded within the endosperm, which is in turn enveloped by the seed coat, making inter-compartmental communication essential for coordinated seed growth. In this context the basic helix-loop-helix domain transcription factor AtZHOUPI (AtZOU) fulfils a key role in both the lysis of the transient endosperm and in embryo cuticle formation in Arabidopsis thaliana. In maize (Zea mays), a cereal with a persistent endosperm, a single gene, ZmZOU, falls into the same phylogenetic clade as AtZOU. Its expression is limited to the endosperm where it peaks during the filling stage. In ZmZOU-RNA interference knock-down lines embryo size is slightly reduced and the embryonic suspensor and the adjacent embryo surrounding region show retarded breakdown. Ectopic expression of ZmZOU reduces stomatal number, possibly due to inappropriate protein interactions. ZmZOU forms functional heterodimers with AtICE/AtSCREAM and the closely related maize proteins ZmICEb and ZmICEc, but its interaction is more efficient with the ZmICEa protein, which shows sequence divergence and only has close homologues in other monocotyledonous species. Consistent with the observation that these complexes can trans-activate target gene promoters from Arabidopsis, ZmZOU partially complements the Atzou-4 mutant. However, structural, trans-activation and gene expression data support the hypothesis that ZmZOU and ZmICEa may have coevolved to form a functional complex unique to monocot seeds. This divergence may explain the reduced functionality of ZmZOU in Arabidopsis, and reflect functional specificities which are unique to the monocotyledon lineage.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Proteínas de Plantas/metabolismo , Sementes/crescimento & desenvolvimento , Zea mays/crescimento & desenvolvimento , Proteínas de Arabidopsis/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Endosperma/genética , Regulação da Expressão Gênica de Plantas , Técnicas de Silenciamento de Genes , Teste de Complementação Genética , Mutação , Proteínas de Plantas/genética , Estômatos de Plantas/genética , Estômatos de Plantas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas , Multimerização Proteica , Sementes/genética , Zea mays/genética
7.
Development ; 140(4): 770-9, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23318634

RESUMO

Seed production in angiosperms requires tight coordination of the development of the embryo and the endosperm. The endosperm-specific transcription factor ZHOUPI has previously been shown to play a key role in this process, by regulating both endosperm breakdown and the formation of the embryonic cuticle. To what extent these processes are functionally linked is, however, unclear. In order to address this issue we have concentrated on the subtilisin-like serine protease encoding gene ABNORMAL LEAF-SHAPE1. Expression of ABNORMAL LEAF-SHAPE1 is endosperm specific, and dramatically decreased in zhoupi mutants. We show that, although ABNORMAL LEAF-SHAPE1 is required for normal embryonic cuticle formation, it plays no role in regulating endosperm breakdown. Furthermore, we show that re-introducing ABNORMAL LEAF-SHAPE1 expression in the endosperm of zhoupi mutants partially rescues embryonic cuticle formation without rescuing their persistent endosperm phenotype. Thus, we conclude that ALE1 can normalize cuticle formation in the absence of endosperm breakdown, and that ZHOUPI thus controls two genetically separable developmental processes. Finally, our genetic study shows that ZHOUPI and ABNORMAL LEAF-SHAPE1 promotes formation of embryonic cuticle via a pathway involving embryonically expressed receptor kinases GASSHO1 and GASSHO2. We therefore provide a molecular framework of inter-tissue communication for embryo-specific cuticle formation during embryogenesis.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/embriologia , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Regulação da Expressão Gênica de Plantas/fisiologia , Sementes/embriologia , Serina Endopeptidases/metabolismo , Transdução de Sinais/fisiologia , Proteínas de Arabidopsis/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Primers do DNA/genética , Regulação da Expressão Gênica no Desenvolvimento/genética , Regulação da Expressão Gênica de Plantas/genética , Genótipo , Técnicas Histológicas , Proteínas Quinases/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Sementes/citologia , Transdução de Sinais/genética , Cloreto de Tolônio
8.
Nat Genet ; 39(6): 792-6, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17496893

RESUMO

Plant roots are able to sense soil nutrient availability. In order to acquire heterogeneously distributed water and minerals, they optimize their root architecture. One poorly understood plant response to soil phosphate (P(i)) deficiency is a reduction in primary root growth with an increase in the number and length of lateral roots. Here we show that physical contact of the Arabidopsis thaliana primary root tip with low-P(i) medium is necessary and sufficient to arrest root growth. We further show that loss-of-function mutations in Low Phosphate Root1 (LPR1) and its close paralog LPR2 strongly reduce this inhibition. LPR1 was previously mapped as a major quantitative trait locus (QTL); the molecular origin of this QTL is explained by the differential allelic expression of LPR1 in the root cap. These results provide strong evidence for the involvement of the root cap in sensing nutrient deficiency, responding to it, or both. LPR1 and LPR2 encode multicopper oxidases (MCOs), highlighting the essential role of MCOs for plant development.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Oxirredutases/metabolismo , Fosfatos/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Sequência de Aminoácidos , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/metabolismo , Mapeamento Cromossômico , Cromossomos de Plantas , Clonagem Molecular , Cobre/química , Regulação da Expressão Gênica de Plantas , Dados de Sequência Molecular , Mutação/genética , Oxirredutases/genética , Coifa/química , Coifa/metabolismo , Raízes de Plantas/genética , Locos de Características Quantitativas , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA de Plantas/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Homologia de Sequência de Aminoácidos , Solo/análise
9.
Plant J ; 77(1): 46-58, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24147836

RESUMO

The transcription factors ARABIDOPSIS THALIANA MERISTEM L1 (ATML1) and PROTODERMAL FACTOR2 (PDF2) are indispensable for epidermal cell-fate specification in Arabidopsis embryos. However, the mechanisms of regulation of these genes, particularly their relationship with cell-cell signalling pathways, although the subject of considerable speculation, remain unclear. Here we demonstrate that the receptor kinase ARABIDOPSIS CRINKLY4 (ACR4) positively affects the expression of ATML1 and PDF2 in seedlings. In contrast, ATML1- and PDF2-containing complexes directly and negatively affect both their own expression and that of ACR4. By modelling the resulting feedback loop, we demonstrate a network structure that is capable of maintaining robust epidermal cell identity post-germination. We show that a second seed-specific signalling pathway involving the subtilase ABNORMAL LEAFSHAPE1 (ALE1) and the receptor kinases GASSHO1 (GSO1) and GASSHO2 (GSO2) acts in parallel to the epidermal loop to control embryonic surface formation via an ATML1/PDF2-independent pathway. Genetic interactions between components of this linear pathway and the epidermal loop suggest that an intact embryo surface is necessary for initiation and/or stabilization of the epidermal loop, specifically during early embryogenesis.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Comunicação Celular , Retroalimentação Fisiológica , Regulação da Expressão Gênica de Plantas , Proteínas de Homeodomínio/genética , Arabidopsis/citologia , Arabidopsis/embriologia , Arabidopsis/fisiologia , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Genótipo , Proteínas de Homeodomínio/metabolismo , Inflorescência/citologia , Inflorescência/embriologia , Inflorescência/genética , Inflorescência/fisiologia , Meristema/citologia , Meristema/embriologia , Meristema/genética , Meristema/fisiologia , Modelos Biológicos , Mutação , Fenótipo , Epiderme Vegetal/citologia , Epiderme Vegetal/embriologia , Epiderme Vegetal/genética , Epiderme Vegetal/fisiologia , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas/genética , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Plântula/citologia , Plântula/embriologia , Plântula/genética , Plântula/fisiologia , Sementes/citologia , Sementes/embriologia , Sementes/genética , Sementes/fisiologia , Transdução de Sinais
10.
Plant Cell ; 23(4): 1523-35, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21521698

RESUMO

In Arabidopsis thaliana, the PHOSPHATE TRANSPORTER1 (PHT1) family encodes the high-affinity phosphate transporters. They are transcriptionally induced by phosphate starvation and require PHOSPHATE TRANSPORTER TRAFFIC FACILITATOR (PHF1) to exit the endoplasmic reticulum (ER), indicating intracellular traffic as an additional level of regulation of PHT1 activity. Our study revealed that PHF1 acts on PHT1, upstream of vesicle coat protein COPII formation, and that additional regulatory events occur during PHT1 trafficking and determine its ER exit and plasma membrane stability. Phosphoproteomic and mutagenesis analyses revealed modulation of PHT1;1 ER export by Ser-514 phosphorylation status. Confocal microscopy analysis of root tip cells showed that PHT1;1 is localized to the plasma membrane and is present in intracellular endocytic compartments. More precisely, PHT1;1 was localized to sorting endosomes associated with prevacuolar compartments. Kinetic analysis of PHT1;1 stability and targeting suggested a modulation of PHT1 internalization from the plasma membrane to the endosomes, followed by either subsequent recycling (in low Pi) or vacuolar degradation (in high Pi). For the latter condition, we identified a rapid mechanism that reduces the pool of PHT1 proteins present at the plasma membrane. This mechanism is regulated by the Pi concentration in the medium and appears to be independent of degradation mechanisms potentially regulated by the PHO2 ubiquitin conjugase. We propose a model for differential trafficking of PHT1 to the plasma membrane or vacuole as a function of phosphate concentration.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Proteínas de Transporte de Fosfato/metabolismo , Biossíntese de Proteínas , Sequência de Aminoácidos , Arabidopsis/metabolismo , Proteínas de Arabidopsis/química , Vesículas Revestidas pelo Complexo de Proteína do Envoltório/metabolismo , Compartimento Celular , Membrana Celular/metabolismo , Retículo Endoplasmático/metabolismo , Endossomos/metabolismo , Proteínas de Fluorescência Verde/metabolismo , Espaço Intracelular/metabolismo , Dados de Sequência Molecular , Especificidade de Órgãos , Proteínas de Transporte de Fosfato/química , Fosfatos/deficiência , Fosfatos/metabolismo , Fosforilação , Estabilidade Proteica , Transporte Proteico , Proteínas Recombinantes de Fusão/metabolismo
11.
Nat Commun ; 14(1): 67, 2023 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-36604410

RESUMO

In plants, as in animals, organ growth depends on mechanical interactions between cells and tissues, and is controlled by both biochemical and mechanical cues. Here, we investigate the control of seed size, a key agronomic trait, by mechanical interactions between two compartments: the endosperm and the testa. By combining experiments with computational modelling, we present evidence that endosperm pressure plays two antagonistic roles: directly driving seed growth, but also indirectly inhibiting it through tension it generates in the surrounding testa, which promotes wall stiffening. We show that our model can recapitulate wild type growth patterns, and is consistent with the small seed phenotype of the haiku2 mutant, and the results of osmotic treatments. Our work suggests that a developmental regulation of endosperm pressure is required to prevent a precocious reduction of seed growth rate induced by force-dependent seed coat stiffening.


Assuntos
Endosperma , Sementes , Endosperma/genética , Regulação da Expressão Gênica de Plantas
12.
Proc Natl Acad Sci U S A ; 106(33): 14174-9, 2009 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-19666499

RESUMO

Inadequate availability of inorganic phosphate (Pi) in the rhizosphere is a common challenge to plants, which activate metabolic and developmental responses to maximize Pi acquisition. The sensory mechanisms that monitor environmental Pi status and regulate root growth via altered meristem activity are unknown. Here, we show that PHOSPHATE DEFICIENCY RESPONSE 2 (PDR2) encodes the single P(5)-type ATPase of Arabidopsis thaliana. PDR2 functions in the endoplasmic reticulum (ER) and is required for proper expression of SCARECROW (SCR), a key regulator of root patterning, and for stem-cell maintenance in Pi-deprived roots. We further show that the multicopper oxidase encoded by LOW PHOSPHATE ROOT 1 (LPR1) is targeted to the ER and that LPR1 and PDR2 interact genetically. Because the expression domains of both genes overlap in the stem-cell niche and distal root meristem, we propose that PDR2 and LPR1 function together in an ER-resident pathway that adjusts root meristem activity to external Pi. Our data indicate that the Pi-conditional root phenotype of pdr2 is not caused by increased Fe availability in low Pi; however, Fe homeostasis modifies the developmental response of root meristems to Pi availability.


Assuntos
Adenosina Trifosfatases/fisiologia , Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Retículo Endoplasmático/metabolismo , Meristema/fisiologia , Oxirredutases/fisiologia , Adenosina Trifosfatases/biossíntese , Proteínas de Arabidopsis/biossíntese , Proteínas de Arabidopsis/fisiologia , Regulação da Expressão Gênica de Plantas , Imunoprecipitação , Microscopia Confocal/métodos , Modelos Biológicos , Modelos Genéticos , Oxirredutases/biossíntese , Oxirredutases/metabolismo , Fenótipo , Fosfatos/metabolismo , Raízes de Plantas/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Células-Tronco/metabolismo
13.
Plant J ; 64(5): 775-89, 2010 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21105925

RESUMO

Phosphate is a crucial and often limiting nutrient for plant growth. To obtain inorganic phosphate (P(i) ), which is very insoluble, and is heterogeneously distributed in the soil, plants have evolved a complex network of morphological and biochemical processes. These processes are controlled by a regulatory system triggered by P(i) concentration, not only present in the medium (external P(i) ), but also inside plant cells (internal P(i) ). A 'split-root' assay was performed to mimic a heterogeneous environment, after which a transcriptomic analysis identified groups of genes either locally or systemically regulated by P(i) starvation at the transcriptional level. These groups revealed coordinated regulations for various functions associated with P(i) starvation (including P(i) uptake, P(i) recovery, lipid metabolism, and metal uptake), and distinct roles for members in gene families. Genetic tools and physiological analyses revealed that genes that are locally regulated appear to be modulated mostly by root development independently of the internal P(i) content. By contrast, internal P(i) was essential to promote the activation of systemic regulation. Reducing the flow of P(i) had no effect on the systemic response, suggesting that a secondary signal, independent of P(i) , could be involved in the response. Furthermore, our results display a direct role for the transcription factor PHR1, as genes systemically controlled by low P(i) have promoters enriched with P1BS motif (PHR1-binding sequences). These data detail various regulatory systems regarding P(i) starvation responses (systemic versus local, and internal versus external P(i) ), and provide tools to analyze and classify the effects of P(i) starvation on plant physiology.


Assuntos
Arabidopsis/genética , Perfilação da Expressão Gênica , Fosfatos/metabolismo , Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , RNA de Plantas/genética , Transdução de Sinais , Transcrição Gênica
14.
Plant Mol Biol ; 73(4-5): 533-46, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20437080

RESUMO

Many eukaryotic genomes have experienced ancient whole-genome duplication (WGD) followed by massive gene loss. These eliminations were not random since some gene families were preferentially retained as duplicates. The gene balance hypothesis suggests that those genes with dosage reduction can imbalance their interacting partners or complex, resulting in decreased fitness. In Arabidopsis, the cytoplasmic ribosomal proteins (RP) are encoded by gene families with at least two members. We have focused our study on the two RPS6 genes in an attempt to understand why they have been retained as duplicates. We demonstrate that RPS6 function is vital for the plant. We also show that reducing the level of RPS6 accumulation (in the knock-out rps6a or rps6b single mutants, or in the double heterozygous RPS6A/rps6a,RPS6B/rps6b), confers a slow growth phenotype (haplodeficiency). Importantly, we demonstrate that the functions of two RPS6 genes are redundant and interchangeable. Finally, like in most other described Arabidopsis rp mutants, we observed that a reduced RPS6 level slightly alters the dorsoventral leaf patterning. Our results support the idea that the Arabidopsis RPS6 gene duplicates were evolutionarily retained in order to maintain an expression level necessary to sustain the translational demand of the cell, in agreement with the gene balance hypothesis.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Arabidopsis/metabolismo , Citoplasma/metabolismo , Proteína S6 Ribossômica/metabolismo , Proteínas Ribossômicas/genética , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/metabolismo , Gametogênese , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Teste de Complementação Genética , Meristema/genética , Mutação/genética , Fenótipo , Folhas de Planta/genética , Pólen/crescimento & desenvolvimento , Polirribossomos/metabolismo , Proteínas Ribossômicas/metabolismo
15.
J Exp Bot ; 60(9): 2653-64, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19443614

RESUMO

Molecular chaperones of the heat shock cognate 70 kDa (HSC70) family are highly conserved in all living organisms and assist nascent protein folding in normal physiological conditions as well as in biotic and abiotic stress conditions. In the absence of specific inhibitors or viable knockout mutants, cytosolic/nuclear HSC70-1 overexpression (OE) and mutants in the HSC70 co-chaperone SGT1 (suppressor of G(2)/M allele of skp1) were used as genetic tools to identify HSC70/SGT1 functions in Arabidopsis development and abiotic stress responses. HSC70-1 OE caused a reduction in root and shoot meristem activities, thus explaining the dwarfism of those plants. In addition, HSC70-1 OE did not impair auxin-dependent phenotypes, suggesting that SGT1 functions previously identified in auxin signalling are HSC70 independent. While responses to abiotic stimuli such as UV-C exposure, phosphate starvation, or seedling de-etiolation were not perturbed by HSC70-1 OE, it specifically conferred gamma-ray hypersensitivity and tolerance to salt, cadmium (Cd), and arsenic (As). Cd and As perception was not perturbed, but plants overexpressing HSC70-1 accumulated less Cd, thus providing a possible molecular explanation for their tolerance phenotype. In summary, genetic evidence is provided for HSC70-1 involvement in a limited set of physiological processes, illustrating the essential and yet specific functions of this chaperone in development and abiotic stress responses in Arabidopsis.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/crescimento & desenvolvimento , Núcleo Celular/metabolismo , Citosol/metabolismo , Regulação da Expressão Gênica de Plantas , Proteínas de Choque Térmico HSC70/metabolismo , Estresse Fisiológico , Arabidopsis/genética , Arabidopsis/fisiologia , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/genética , Arsênio/metabolismo , Cádmio/metabolismo , Núcleo Celular/genética , Raios gama , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Glucosiltransferases/genética , Glucosiltransferases/metabolismo , Proteínas de Choque Térmico HSC70/genética , Ácidos Indolacéticos/metabolismo , Tolerância ao Sal , Transdução de Sinais , Raios Ultravioleta
16.
Science ; 364(6435): 57-62, 2019 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-30948546

RESUMO

Rho guanosine triphosphatases (GTPases) are master regulators of cell signaling, but how they are regulated depending on the cellular context is unclear. We found that the phospholipid phosphatidylserine acts as a developmentally controlled lipid rheostat that tunes Rho GTPase signaling in Arabidopsis Live superresolution single-molecule imaging revealed that the protein Rho of Plants 6 (ROP6) is stabilized by phosphatidylserine into plasma membrane nanodomains, which are required for auxin signaling. Our experiments also revealed that the plasma membrane phosphatidylserine content varies during plant root development and that the level of phosphatidylserine modulates the quantity of ROP6 nanoclusters induced by auxin and hence downstream signaling, including regulation of endocytosis and gravitropism. Our work shows that variations in phosphatidylserine levels are a physiological process that may be leveraged to regulate small GTPase signaling during development.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimologia , Arabidopsis/crescimento & desenvolvimento , Proteínas Monoméricas de Ligação ao GTP/metabolismo , Fosfatidilserinas/metabolismo , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Membrana Celular/química , Membrana Celular/metabolismo , Endocitose/genética , Regulação da Expressão Gênica de Plantas , Gravitropismo/genética , Ácidos Indolacéticos/metabolismo , Proteínas Monoméricas de Ligação ao GTP/genética , Fosfatidilserinas/farmacologia , Raízes de Plantas/enzimologia , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Transdução de Sinais , Imagem Individual de Molécula
17.
Nat Commun ; 8: 15300, 2017 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-28504266

RESUMO

Environmental cues profoundly modulate cell proliferation and cell elongation to inform and direct plant growth and development. External phosphate (Pi) limitation inhibits primary root growth in many plant species. However, the underlying Pi sensory mechanisms are unknown. Here we genetically uncouple two Pi sensing pathways in the root apex of Arabidopsis thaliana. First, the rapid inhibition of cell elongation in the transition zone is controlled by transcription factor STOP1, by its direct target, ALMT1, encoding a malate channel, and by ferroxidase LPR1, which together mediate Fe and peroxidase-dependent cell wall stiffening. Second, during the subsequent slow inhibition of cell proliferation in the apical meristem, which is mediated by LPR1-dependent, but largely STOP1-ALMT1-independent, Fe and callose accumulate in the stem cell niche, leading to meristem reduction. Our work uncovers STOP1 and ALMT1 as a signalling pathway of low Pi availability and exuded malate as an unexpected apoplastic inhibitor of root cell wall expansion.


Assuntos
Proteínas de Arabidopsis/metabolismo , Transportadores de Ânions Orgânicos/metabolismo , Fosfatos/metabolismo , Raízes de Plantas/metabolismo , Fatores de Transcrição/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Crescimento Celular , Parede Celular/genética , Parede Celular/metabolismo , Regulação da Expressão Gênica de Plantas , Ferro/metabolismo , Malatos/metabolismo , Meristema/citologia , Meristema/genética , Meristema/metabolismo , Transportadores de Ânions Orgânicos/genética , Oxirredutases/genética , Oxirredutases/metabolismo , Peroxidase/genética , Peroxidase/metabolismo , Raízes de Plantas/citologia , Raízes de Plantas/genética , Plantas Geneticamente Modificadas , Transdução de Sinais/genética , Fatores de Transcrição/genética
18.
Nat Commun ; 6: 6382, 2015 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-25702924

RESUMO

Endogenous mechanical stresses regulate plant growth and development. Tensile stress in epidermal cells affects microtubule reorientation and anisotropic cell wall deposition, and mechanical stimulus at the meristem regulates trafficking and polar localization of auxin transporters. However, the mechanical regulation of other plant growth regulators has not been demonstrated. Here we propose that during seed growth, mechanical stress exerted by the expanding embryo and endosperm is perceived by a specific mechanosensitive cell layer in the seed coat. We show that the adaxial epidermis of the outer integument thickens its cell wall in a mechanosensitive fashion, demonstrates microtubule dynamics consistent with mechanical stress perception and shows mechanosensitive expression of ELA1, a regulator of seed size and gibberellic acid (GA) metabolism. By exploiting physical and genetic compartmentalization, and combining genetic and surgical techniques, we propose a mechanistic link between mechanical stress and GA accumulation that regulates seed development.


Assuntos
Arabidopsis/fisiologia , Parede Celular/fisiologia , Mecanotransdução Celular , Microtúbulos/fisiologia , Sementes/crescimento & desenvolvimento , Arabidopsis/citologia , Proteínas de Arabidopsis/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Giberelinas/metabolismo , Sementes/citologia
19.
Plant Signal Behav ; 8(6): e24368, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23531691

RESUMO

ZHOUPI, a unique and highly conserved bHLH transcription factor, controls both endosperm breakdown and embryonic surface formation during Arabidopsis seed development. We have demonstrated that these two processes are distinct, and that ZHOUPI regulates embryonic surface formation via a signaling pathway mediated by the subtilisin-like serine protease ABNORMAL LEAF SHAPE1, and the receptor-kinases GASSHO1 and GASSHO2. Gene expression profiling in mutant backgrounds has permitted the identification of genes whose expression depends on both ZHOUPI and ABNORMAL LEAF SHAPE1 and genes whose expression depends uniquely on ZHOUPI. The latter are presumably involved specifically in endosperm breakdown, and we discuss this poorly understood process in the light of our results. Finally, we consider the potential ancestral role of ZHOUPI and discuss how its relationship with ABNORMAL LEAF SHAPE1 may have evolved.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Sementes/crescimento & desenvolvimento , Serina Endopeptidases/metabolismo , Arabidopsis/crescimento & desenvolvimento , Morte Celular , Endosperma/metabolismo
20.
Plant Signal Behav ; 8(12): e27491, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24398513

RESUMO

The plant cuticle, a dynamic interface between plants and their environment, is formed by the secretion of hydrophobic lipids and waxes into the outer wall of aerial epidermal cells. Cuticle formation is such a ubiquitous feature of epidermal cells, and is of such fundamental importance for plant survival, that identifying and understanding specific developmental roles for this structure has been a major challenge for plant scientists. In recent work, we have tried to understand the functional relationships between a signaling feedback loop required for epidermal cell specification in developing plant embryos, and a seed specific signaling cascade, involving components localized both in the embryo and in the embryo surrounding endosperm, and necessary for embryo cuticle function. Analysis of the strongly synergistic genetic relationships between these 2 independent pathways, combined with mathematical simulations of the behavior of the signaling feedback loop, have allowed us to propose an important, and hitherto unsuspected, role for the embryonic cuticle as an apoplastic diffusion barrier, necessary for preventing the excessive diffusion of developmentally important signaling molecules away from developing embryo into surrounding tissues.


Assuntos
Epiderme Vegetal/embriologia , Transporte Biológico , Difusão , Modelos Biológicos , Transdução de Sinais
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