Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 47
Filtrar
Filtros adicionais











Intervalo de ano
1.
Development ; 145(10)2018 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-29695610

RESUMO

The epidermis is hypothesized to play a signalling role during plant development. One class of mutants showing defects in signal transduction and radial patterning are those in sterol biosynthesis. The expectation is that living cells require sterols, but it is not clear that all cell types express sterol biosynthesis genes. The HYDRA1 (HYD1) gene of Arabidopsis encodes sterol Δ8-Δ7 isomerase, and although hyd1 seedlings are defective in radial patterning across several tissues, we show that the HYD1 gene is expressed most strongly in the root epidermis. Transgenic activation of HYD1 transcription in the epidermis of hyd1 null mutants reveals a major role in root patterning and growth. HYD1 expression in the vascular tissues and root meristem, though not endodermis or pericycle, also leads to some phenotypic rescue. Phenotypic rescue is associated with rescued patterning of the PIN1 and PIN2 auxin efflux carriers. The importance of the epidermis in controlling root growth and development is proposed to be, in part, due to its role as a site for sterol biosynthesis, and auxin is a candidate for the non-cell-autonomous signal.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/crescimento & desenvolvimento , Meristema/crescimento & desenvolvimento , Raízes de Plantas/crescimento & desenvolvimento , Esteroide Isomerases/metabolismo , Esteróis/metabolismo , Arabidopsis/embriologia , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Regulação da Expressão Gênica de Plantas/genética , Ácidos Indolacéticos/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Meristema/embriologia , Epiderme Vegetal/citologia , Epiderme Vegetal/genética , Epiderme Vegetal/metabolismo , Plântula/embriologia , Plântula/genética , Transdução de Sinais/genética , Esteroide Isomerases/genética , Ativação Transcricional/genética
2.
PLoS Genet ; 13(9): e1007036, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28961247

RESUMO

Chaperonins are a class of molecular chaperones that assist in the folding and assembly of a wide range of substrates. In plants, chloroplast chaperonins are composed of two different types of subunits, Cpn60α and Cpn60ß, and duplication of Cpn60α and Cpn60ß genes occurs in a high proportion of plants. However, the importance of multiple Cpn60α and Cpn60ß genes in plants is poorly understood. In this study, we found that loss-of-function of CPNA2 (AtCpn60α2), a gene encoding the minor Cpn60α subunit in Arabidopsis thaliana, resulted in arrested embryo development at the globular stage, whereas the other AtCpn60α gene encoding the dominant Cpn60α subunit, CPNA1 (AtCpn60α1), mainly affected embryonic cotyledon development at the torpedo stage and thereafter. Further studies demonstrated that CPNA2 can form a functional chaperonin with CPNB2 (AtCpn60ß2) and CPNB3 (AtCpn60ß3), while the functional partners of CPNA1 are CPNB1 (AtCpn60ß1) and CPNB2. We also revealed that the functional chaperonin containing CPNA2 could assist the folding of a specific substrate, KASI (ß-ketoacyl-[acyl carrier protein] synthase I), and that the KASI protein level was remarkably reduced due to loss-of-function of CPNA2. Furthermore, the reduction in the KASI protein level was shown to be the possible cause for the arrest of cpna2 embryos. Our findings indicate that the two Cpn60α subunits in Arabidopsis play different roles during embryo development through forming distinct chaperonins with specific AtCpn60ß to assist the folding of particular substrates, thus providing novel insights into functional divergence of Cpn60α subunits in plants.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Chaperoninas/metabolismo , Regulação da Expressão Gênica de Plantas , Genes de Plantas , 3-Oxoacil-(Proteína de Transporte de Acila) Sintase/genética , 3-Oxoacil-(Proteína de Transporte de Acila) Sintase/metabolismo , Proteína de Transporte de Acila/genética , Proteína de Transporte de Acila/metabolismo , Sequência de Aminoácidos , Arabidopsis/embriologia , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/genética , Chaperoninas/genética , Cloroplastos/genética , Cloroplastos/metabolismo , Clonagem Molecular , Cotilédone/embriologia , Cotilédone/genética , Duplicação Gênica , Conformação Proteica , Plântula/embriologia , Espectrometria de Massas em Tandem
3.
Protoplasma ; 254(3): 1317-1322, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-27631339

RESUMO

In 2009, the draft genome of the reference inbred line of maize (Zea mays L. spp. mays cv. B73) was published so that, using this specific corn variety, molecular analyses of physiological processes became possible. However, the morphology and developmental patterns of B73 maize, compared with that of the more frequently used hybrid varieties, have not yet been analyzed. Here, we describe organ development in seedlings of B73 maize and in those of six other hybrid cultivars, and document significant morphological as well as quantitative differences between these varieties of Z. mays. In a second set of experiments, we used etiolated seedlings of B73 maize to analyze the effect of blue light (BL) on the patterns of proteins in the tip vs. growing region of this sheath-like organ. By using two-dimensional difference gel electrophoresis (2D DIGE), coupled with tandem mass spectrometry, we detected, in the microsomal fraction of maize coleoptile tips, rapid changes in the abundance of protein spots of maize phototropin 1 and several metabolic enzymes. In the sub-apical (growing) region of the coleoptile, proteomic changes were less pronounced. These results suggest that the tip of the coleoptile of B73 maize may serve as a unique model system for dissecting BL responses in a light-sensitive plant organ of known function.


Assuntos
Cotilédone/metabolismo , Luz , Proteínas de Plantas/metabolismo , Caules de Planta/metabolismo , Plântula/crescimento & desenvolvimento , Zea mays/embriologia , Quimera/crescimento & desenvolvimento , Glucosiltransferases/metabolismo , Lipoxigenases/metabolismo , Fototropinas/metabolismo , Proteoma/metabolismo , Proteômica , Plântula/embriologia , Zea mays/metabolismo
4.
Sci Rep ; 6: 25581, 2016 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-27151146

RESUMO

Early establishment of endophytes can play a role in pathogen suppression and improve seedling development. One route for establishment of endophytes in seedlings is transmission of bacteria from the parent plant to the seedling via the seed. In wheat seeds, it is not clear whether this transmission route exists, and the identities and location of bacteria within wheat seeds are unknown. We identified bacteria in the wheat (Triticum aestivum) cv. Hereward seed environment using embryo excision to determine the location of the bacterial load. Axenic wheat seedlings obtained with this method were subsequently used to screen a putative endophyte bacterial isolate library for endophytic competency. This absence of bacteria recovered from seeds indicated low bacterial abundance and/or the presence of inhibitors. Diversity of readily culturable bacteria in seeds was low with 8 genera identified, dominated by Erwinia and Paenibacillus. We propose that anatomical restrictions in wheat limit embryo associated vertical transmission, and that bacterial load is carried in the seed coat, crease tissue and endosperm. This finding facilitates the creation of axenic wheat plants to test competency of putative endophytes and also provides a platform for endophyte competition, plant growth, and gene expression studies without an indigenous bacterial background.


Assuntos
Bactérias/metabolismo , Endófitos/fisiologia , Plântula/embriologia , Plântula/microbiologia , Sementes/embriologia , Sementes/microbiologia , Triticum/embriologia , Triticum/microbiologia , Bactérias/isolamento & purificação , RNA Ribossômico 16S/genética
5.
Plant Cell ; 27(5): 1497-511, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25966764

RESUMO

Phospholipids are highly conserved and essential components of biological membranes. The major phospholipids, phosphatidylethanolamine and phosphatidylcholine (PtdCho), are synthesized by the transfer of the phosphoethanolamine or phosphocholine polar head group, respectively, to the diacylglycerol backbone. The metabolism of the polar head group characterizing each phospholipid class is poorly understood; thus, the biosynthetic pathway of major phospholipids remains elusive in Arabidopsis thaliana. The choline/ethanolamine kinase (CEK) family catalyzes the initial steps of phospholipid biosynthesis. Here, we analyzed the function of the four CEK family members present in Arabidopsis. Knocking out of CEK4 resulted in defective embryo development, which was complemented by transformation of genomic CEK4. Reciprocal genetic crossing suggested that CEK4 knockout causes embryonic lethality, and microscopy analysis of the aborted embryos revealed developmental arrest after the heart stage, with no defect being found in the pollen. CEK4 is preferentially expressed in the vasculature, organ boundaries, and mature embryos, and CEK4 was mainly localized to the plasma membrane. Overexpression of CEK4 in wild-type Arabidopsis increased the levels of PtdCho in seedlings and mature siliques and of major membrane lipids in seedlings and triacylglycerol in mature siliques. CEK4 may be the plasma membrane-localized isoform of the CEK family involved in the rate-limiting step of PtdCho biosynthesis and appears to be required for embryo development in Arabidopsis.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimologia , Colina Quinase/metabolismo , Fosfotransferases (Aceptor do Grupo Álcool)/metabolismo , Sequência de Aminoácidos , Arabidopsis/citologia , Arabidopsis/embriologia , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Membrana Celular/enzimologia , Colina/metabolismo , Colina Quinase/genética , Diglicerídeos/metabolismo , Etanolaminas/metabolismo , Técnicas de Inativação de Genes , Genes Reporter , Isoenzimas , Dados de Sequência Molecular , Mutagênese Insercional , Fosfatidilcolinas/metabolismo , Fosfatidiletanolaminas/metabolismo , Fosfotransferases (Aceptor do Grupo Álcool)/genética , Plântula/citologia , Plântula/embriologia , Plântula/enzimologia , Plântula/genética , Alinhamento de Sequência
6.
J Exp Bot ; 66(11): 3071-83, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25805716

RESUMO

Towards the aim of examining the potential function of KORRIGAN (KOR), a highly conserved membrane-bound endoglucanase, in reproductive development, here transgenic evidence is provided that a cotton (Gossypium hirsutum) endoglucanase, GhKOR1, plays significant roles in endosperm and embryo development. RNA interference (RNAi)- and co-suppression-mediated down-regulation of GhKOR1 resulted in smaller filial tissue and reduced seed weight, which were characterized by disrupted endosperm cellularization and delayed embryo development, leading to a delayed germination and a weak growth of seedlings early in development. The transgenic seeds exhibited fewer and smaller endosperm cells with irregular and brittle cell walls, and their embryos developed only to the globular stage at 10 days post-anthesis (DPA) when the wild-type endosperm has become highly cellularized and the embryo has progressed to the heart stage. The transgenic seed also displayed a significant reduction of callose in the seed coat transfer cells and reduced cellulose content both in the seed coat and in mature fibres. These findings demonstrate that GhKOR1 is required for the developmental of both seed filial and maternal tissues and the establishment of seedling vigour.


Assuntos
Celulase/genética , Regulação da Expressão Gênica de Plantas , Gossypium/enzimologia , Parede Celular/metabolismo , Celulase/metabolismo , Regulação para Baixo , Endosperma/embriologia , Endosperma/enzimologia , Endosperma/genética , Endosperma/fisiologia , Regulação da Expressão Gênica no Desenvolvimento , Germinação , Gossypium/embriologia , Gossypium/genética , Gossypium/fisiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Interferência de RNA , Plântula/embriologia , Plântula/enzimologia , Plântula/genética , Plântula/fisiologia , Sementes/embriologia , Sementes/enzimologia , Sementes/genética , Sementes/fisiologia
7.
Genet Mol Res ; 14(1): 1096-105, 2015 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-25730049

RESUMO

Mature embryos in tissue cultures are advantageous because of their abundance and rapid germination, which reduces genomic instability problems. In this study, 2-day-old isolated mature barley embryos were infected with 2 Agrobacterium hypervirulent strains (AGL1 and EHA105), followed by a 3-day period of co-cultivation in the presence of L-cystein amino acid. Chimeric expression of the b-glucuronidase gene (gusA) directed by a viral promoter of strawberry vein banding virus was observed in coleoptile epidermal cells and seminal roots in 5-day-old germinated seedlings. In addition to varying infectivity patterns in different strains, there was a higher ratio of transient b-glucuronidase expression in developing coleoptiles than in embryonic roots, indicating the high competency of shoot apical meristem cells in the mature embryo. A total of 548 explants were transformed and 156 plants developed to maturity on G418 media after 18-25 days. We detected transgenes in 74% of the screened plant leaves by polymerase chain reaction, and 49% of these expressed neomycin phosphotransferase II gene following AGL1 transformation. Ten randomly selected T0 transformants were analyzed using thermal asymmetric interlaced polymerase chain reaction and 24 fragments ranged between 200-600 base pairs were sequenced. Three of the sequences flanked with transferred-DNA showed high similarity to coding regions of the barley genome, including alpha tubulin5, homeobox 1, and mitochondrial 16S genes. We observed 70-200-base pair filler sequences only in the coding regions of barley in this study.


Assuntos
Hordeum/genética , Plantas Geneticamente Modificadas/genética , Plântula/genética , Transformação Genética , Agrobacterium tumefaciens/genética , Vetores Genéticos , Genoma de Planta , Genômica , Germinação/genética , Hordeum/embriologia , Hordeum/crescimento & desenvolvimento , Canamicina Quinase/genética , Meristema/embriologia , Meristema/genética , Meristema/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/embriologia , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Plântula/embriologia , Plântula/crescimento & desenvolvimento , Sementes/genética , Sementes/crescimento & desenvolvimento , Transgenes
8.
Plant Cell Physiol ; 55(12): 2112-25, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25282558

RESUMO

LEC1, LEC2, FUS3 and ABI3 (collectively abbreviated LEC/ABI3 here) are required for embryo maturation and have apparent roles in repressing post-germinative development. lec mutant embryos exhibit some heterochronic characteristics, as exemplified by the development of true leaf-like cotyledons during embryogenesis. Although the roles of LEC/ABI3 as positive regulators of embryo maturation have been extensively studied, their roles in the negative regulation of post-germinative development have not been explored in detail. Based on microarray analyses, we chose PYK10, which encodes an endoplasmic reticulum (ER)-body-localized protein, as a molecular marker of post-germinative development. lec/abi3 embryos exhibited PYK10 misexpression and the formation of 'constitutive' ER-bodies, which develop specifically during the seedling stage, confirming the heterochronic nature of these mutants at both the gene expression and cellular levels. The PYK10 reporter expression in lec1 embryos started as early as the globular-heart transition stage. The onset of PYK10 promoter-enhanced green fluorescent protein (EGFP) reporter expression occurred in a stochastic, cell-by-cell manner in both developing lec/abi3 embryos and germinating wild-type seedlings. Additionally, clustered EGFP-positive cells were frequently found along cell files, probably representing the transmission of the expression state via cell division. These observations, together with the results of the experiments using PYK10-EGFP/PYK10-CFP double reporter transgenic lines and the analyses of H3K27me3 levels in the PYK10 chromatin, suggested the involvement of epigenetic mechanisms in repressing post-germinative genes during embryogenesis and derepressing these genes upon the transition to post-germinative development.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/embriologia , Epigênese Genética/fisiologia , Regulação da Expressão Gênica no Desenvolvimento , beta-Glucosidase/genética , Arabidopsis/citologia , Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas Estimuladoras de Ligação a CCAAT/genética , Proteínas Estimuladoras de Ligação a CCAAT/metabolismo , Cotilédone/citologia , Cotilédone/embriologia , Cotilédone/genética , Retículo Endoplasmático/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Genes Reporter , Germinação/genética , Mutação , Análise de Sequência com Séries de Oligonucleotídeos , Folhas de Planta/citologia , Folhas de Planta/embriologia , Folhas de Planta/genética , Plantas Geneticamente Modificadas , Plântula/citologia , Plântula/embriologia , Plântula/genética , Sementes/citologia , Sementes/embriologia , Sementes/genética , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , beta-Glucosidase/metabolismo
9.
Plant Cell ; 26(7): 3090-100, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25052714

RESUMO

Purine nucleotides can be fully catabolized by plants to recycle nutrients. We have isolated a urate oxidase (uox) mutant of Arabidopsis thaliana that accumulates uric acid in all tissues, especially in the developing embryo. The mutant displays a reduced germination rate and is unable to establish autotrophic growth due to severe inhibition of cotyledon development and nutrient mobilization from the lipid reserves in the cotyledons. The uox mutant phenotype is suppressed in a xanthine dehydrogenase (xdh) uox double mutant, demonstrating that the underlying cause is not the defective purine base catabolism, or the lack of UOX per se, but the elevated uric acid concentration in the embryo. Remarkably, xanthine accumulates to similar levels in the xdh mutant without toxicity. This is paralleled in humans, where hyperuricemia is associated with many diseases whereas xanthinuria is asymptomatic. Searching for the molecular cause of uric acid toxicity, we discovered a local defect of peroxisomes (glyoxysomes) mostly confined to the cotyledons of the mature embryos, which resulted in the accumulation of free fatty acids in dry seeds. The peroxisomal defect explains the developmental phenotypes of the uox mutant, drawing a novel link between uric acid and peroxisome function, which may be relevant beyond plants.


Assuntos
Arabidopsis/enzimologia , Peroxissomos/metabolismo , Urato Oxidase/metabolismo , Ácido Úrico/metabolismo , Arabidopsis/embriologia , Arabidopsis/genética , Arabidopsis/ultraestrutura , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Cotilédone/embriologia , Cotilédone/enzimologia , Cotilédone/genética , Cotilédone/ultraestrutura , Ácidos Graxos/metabolismo , Germinação , Mutação , Fenótipo , Componentes Aéreos da Planta/embriologia , Componentes Aéreos da Planta/enzimologia , Componentes Aéreos da Planta/genética , Componentes Aéreos da Planta/ultraestrutura , Regiões Promotoras Genéticas/genética , Nucleotídeos de Purina/metabolismo , Plântula/embriologia , Plântula/enzimologia , Plântula/genética , Plântula/ultraestrutura , Sementes/embriologia , Sementes/enzimologia , Sementes/genética , Sementes/ultraestrutura , Urato Oxidase/genética , Ácido Úrico/química , Xantina/química , Xantina/metabolismo , Xantina Desidrogenase/genética , Xantina Desidrogenase/metabolismo
10.
ScientificWorldJournal ; 2014: 263642, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24963505

RESUMO

An alternative in vitro protocol for embryo induction directly from intact living seedlings of Phalaenopsis aphrodite subspecies formosana was established in this study. Without the supplementation of plant growth regulators (PGRs), no embryos were obtained from all the seedlings when cultured on the solid medium. In contrast, embryos formed from the seedlings on the 2-layer medium and the 2-step culture system without the use of PGRs. It was found that the age of the seedlings affected embryo induction. The 2-month-old seedlings typically had higher embryogenic responses when compared with the 4-month-old seedlings in the 2-layer medium or 2-step system. For the 2-month-old seedlings, 1 mg/L TDZ resulted in the highest number of embryos at the distal site of the shoot. However, on the leaves' surface, 0.5 mg/L TDZ induced the highest number of embryos. When the 2-month-old seedlings were cultured using the 2-step method at 1 mg/L of TDZ, the highest embryogenic response was obtained, with an average of 44 embryos formed on each seedling. These adventitious embryos were able to convert into plantlets in a PGR-free 1/2 MS medium, and the plantlets had normal morphology and growth.


Assuntos
Orchidaceae/embriologia , Técnicas de Embriogênese Somática de Plantas/métodos , Orchidaceae/efeitos dos fármacos , Reguladores de Crescimento de Planta/farmacologia , Plântula/efeitos dos fármacos , Plântula/embriologia
11.
J Plant Physiol ; 171(13): 1132-41, 2014 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-24973585

RESUMO

Deep dormancy of apple (Malus domestica Borkh.) embryos can be overcome by short-term pre-treatment with nitric oxide (NO) or hydrogen cyanide (HCN). Dormancy alleviation of embryos modulated by NO or HCN and the first step of germination depend on temporary increased production of reactive oxygen species (ROS). Direct oxidative attack on some amino acid residues or secondary reactions via reactive carbohydrates and lipids can lead to the formation of protein carbonyl derivatives. Protein carbonylation is a widely accepted covalent and irreversible modification resulting in inhibition or alteration of enzyme/protein activities. It also increases the susceptibility of proteins to proteolytic degradation. The aim of this work was to investigate protein carbonylation in germinating apple embryos, the dormancy of which was removed by pre-treatment with NO or HCN donors. It was performed using a quantitative spectrophotometric method, while patterns of carbonylated protein in embryo axes were analyzed by immunochemical techniques. The highest concentration of protein carbonyl groups was observed in dormant embryos. It declined in germinating embryos pre-treated with NO or HCN, suggesting elevated degradation of modified proteins during seedling formation. A decrease in the concentration of carbonylated proteins was accompanied by modification in proteolytic activity in germinating apple embryos. A strict correlation between the level of protein carbonyl groups and cotyledon growth and greening was detected. Moreover, direct in vitro carbonylation of BSA treated with NO or HCN donors was analyzed, showing action of both signaling molecules as protein oxidation agents.


Assuntos
Cianeto de Hidrogênio/farmacologia , Malus/fisiologia , Óxido Nítrico/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Cotilédone/efeitos dos fármacos , Cotilédone/embriologia , Cotilédone/fisiologia , Germinação , Peróxido de Hidrogênio/metabolismo , Malus/efeitos dos fármacos , Malus/embriologia , Oxirredução , Dormência de Plantas , Proteínas de Plantas/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/embriologia , Raízes de Plantas/fisiologia , Carbonilação Proteica , Plântula/efeitos dos fármacos , Plântula/embriologia , Plântula/fisiologia , Sementes/efeitos dos fármacos , Sementes/embriologia , Sementes/fisiologia
12.
J Exp Bot ; 65(1): 169-83, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24218326

RESUMO

Mitogen-activated protein kinase (MAPKs) cascades are signal transduction modules highly conserved in all eukaryotes regulating various aspects of plant biology, including stress responses and developmental programmes. In this study, we characterized the role of MAPK 6 (MPK6) in Arabidopsis embryo development and in post-embryonic root system architecture. We found that the mpk6 mutation caused altered embryo development giving rise to three seed phenotypes that, post-germination, correlated with alterations in root architecture. In the smaller seed class, mutant seedlings failed to develop the primary root, possibly as a result of an earlier defect in the division of the hypophysis cell during embryo development, but they had the capacity to develop adventitious roots to complete their life cycle. In the larger class, the MPK6 loss of function did not cause any evident alteration in seed morphology, but the embryo and the mature seed were bigger than the wild type. Seedlings developed from these bigger seeds were characterized by a primary root longer than that of the wild type, accompanied by significantly increased lateral root initiation and more and longer root hairs. Apparently, the increment in primary root growth resulted from an enhanced cell production and cell elongation. Our data demonstrated that MPK6 plays an important role during embryo development and acts as a repressor of primary and lateral root development.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/enzimologia , Regulação da Expressão Gênica de Plantas , Sistema de Sinalização das MAP Quinases , Proteínas Quinases Ativadas por Mitógeno/genética , Alelos , Arabidopsis/embriologia , Arabidopsis/genética , Arabidopsis/fisiologia , Proteínas de Arabidopsis/metabolismo , Divisão Celular , Tamanho Celular , Regulação da Expressão Gênica no Desenvolvimento , Germinação , Quinases de Proteína Quinase Ativadas por Mitógeno/genética , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Mutação , Fenótipo , Raízes de Plantas/embriologia , Raízes de Plantas/enzimologia , Raízes de Plantas/genética , Raízes de Plantas/fisiologia , Plantas Geneticamente Modificadas , Plântula/embriologia , Plântula/enzimologia , Plântula/genética , Plântula/fisiologia , Sementes/embriologia , Sementes/enzimologia , Sementes/genética , Sementes/fisiologia
13.
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
14.
Plant Cell ; 25(1): 134-48, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23362207

RESUMO

The seed maturation genes are specifically and highly expressed during late embryogenesis. In this work, yeast two-hybrid, bimolecular fluorescence complementation, and coimmunoprecipitation assays revealed that HISTONE DEACETYLASE19 (HDA19) interacted with the HIGH-LEVEL EXPRESSION OF SUGAR-INDUCIBLE GENE2-LIKE1 (HSL1), and the zinc-finger CW [conserved Cys (C) and Trp (W) residues] domain of HSL1 was responsible for the interaction. Furthermore, we found that mutations in HDA19 resulted in the ectopic expression of seed maturation genes in seedlings, which was associated with increased levels of gene activation marks, such as Histone H3 acetylation (H3ac), Histone H4 acetylation (H4ac), and Histone H3 Lys 4 tri-methylation (H3K4me3), but decreased levels of the gene repression mark Histone H3 Lys 27 tri-methylation (H3K27me3) in the promoter and/or coding regions. In addition, elevated transcription of certain seed maturation genes was also found in the hsl1 mutant seedlings, which was also accompanied by the enrichment of gene activation marks but decreased levels of the gene repression mark. Chromatin immunoprecipitation assays showed that HDA19 could directly bind to the chromatin of the seed maturation genes. These results suggest that HDA19 and HSL1 may act together to repress seed maturation gene expression during germination. Further genetic analyses revealed that the homozygous hsl1 hda19 double mutants are embryonic lethal, suggesting that HDA19 and HSL1 may play a vital role during embryogenesis.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/embriologia , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Histona Desacetilases/genética , Acetilação , Arabidopsis/citologia , Arabidopsis/fisiologia , Proteínas de Arabidopsis/metabolismo , Imunoprecipitação da Cromatina , Regulação da Expressão Gênica no Desenvolvimento , Histona Desacetilases/metabolismo , Histonas/genética , Histonas/metabolismo , Metilação , Mutação , Especificidade de Órgãos , Plantas Geneticamente Modificadas , Estrutura Terciária de Proteína , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Plântula/citologia , Plântula/embriologia , Plântula/genética , Plântula/fisiologia , Sementes/citologia , Sementes/embriologia , Sementes/genética , Sementes/fisiologia , Técnicas do Sistema de Duplo-Híbrido
15.
Plant J ; 73(5): 862-72, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23167545

RESUMO

Protein phosphorylation is a key molecular switch used to transmit information in biological signalling networks. The output of these signalling circuits is governed by the counteracting activities of protein kinases and phosphatases that determine the direction of the switch. Whereas many kinases have been functionally characterized, it has been difficult to ascribe precise cellular roles to plant phosphatases, which are encoded by enlarged gene families that may provide a high degree of genetic redundancy. In this work we have analysed the role in planta of catalytic subunits of protein phosphatase 2A (PP2A), a family encoded by five genes in Arabidopsis. Our results indicate that the two members of subfamily II, PP2A-C3 and PP2A-C4, have redundant functions in controlling embryo patterning and root development, processes that depend on auxin fluxes. Moreover, polarity of the auxin efflux carrier PIN1 and auxin distribution, determined with the DR5(pro) :GFP proxy, are affected by mutations in PP2A-C3 and PP2A-C4. Previous characterization of mutants in putative PP2A regulatory subunits had established a link between this class of phosphatases and PIN dephosphorylation and subcellular distribution. Building on those findings, the results presented here suggest that PP2A-C3 and PP2A-C4 catalyse this reaction and contribute critically to the establishment of auxin gradients for proper plant development.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimologia , Ácidos Indolacéticos/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Proteína Fosfatase 2/metabolismo , Arabidopsis/embriologia , Arabidopsis/genética , Arabidopsis/fisiologia , Proteínas de Arabidopsis/genética , Transporte Biológico , Padronização Corporal , Domínio Catalítico , Técnicas de Inativação de Genes , Proteínas de Membrana Transportadoras/genética , Meristema/embriologia , Meristema/enzimologia , Meristema/genética , Meristema/fisiologia , Mutação , Fenótipo , Fosforilação , Raízes de Plantas/embriologia , Raízes de Plantas/enzimologia , Raízes de Plantas/genética , Raízes de Plantas/fisiologia , Brotos de Planta/embriologia , Brotos de Planta/enzimologia , Brotos de Planta/genética , Brotos de Planta/fisiologia , Plantas Geneticamente Modificadas , Proteína Fosfatase 2/genética , Transporte Proteico , Proteínas Recombinantes de Fusão , Plântula/embriologia , Plântula/enzimologia , Plântula/genética , Plântula/fisiologia , Transdução de Sinais
16.
Plant J ; 72(6): 922-34, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22900828

RESUMO

A lack of individual plastid ribosomal proteins (PRPs) can have diverse phenotypic effects in Arabidopsis thaliana, ranging from embryo lethality to compromised vitality, with the latter being associated with photosynthetic lesions and decreases in the expression of plastid proteins. In this study, reverse genetics was employed to study the function of eight PRPs, five of which (PRPS1, -S20, -L27, -L28 and -L35) have not been functionally characterised before. In the case of PRPS17, only leaky alleles or RNA interference lines had been analysed previously. PRPL1 and PRPL4 have been described as essential for embryo development, but their mutant phenotypes are analysed in detail here. We found that PRPS20, -L1, -L4, -L27 and -L35 are required for basal ribosome activity, which becomes crucial at the globular stage and during the transition from the globular to the heart stage of embryogenesis. Thus, lack of any of these PRPs leads to alterations in cell division patterns, and embryo development ceases prior to the heart stage. PRPL28 is essential at the latest stages of embryo-seedling development, during the greening process. PRPS1, -S17 and -L24 appear not to be required for basal ribosome activity and the organism can complete its entire life cycle in their absence. Interestingly, despite the prokaryotic origin of plastids, the significance of individual PRPs for plant development cannot be predicted from the relative phenotypic severity of the corresponding mutants in prokaryotic systems.


Assuntos
Arabidopsis/crescimento & desenvolvimento , Proteínas de Cloroplastos/metabolismo , Regulação da Expressão Gênica de Plantas , Proteínas Ribossômicas/metabolismo , Arabidopsis/embriologia , Arabidopsis/genética , Arabidopsis/fisiologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Clorofila/metabolismo , Proteínas de Cloroplastos/genética , Mutagênese Insercional , Fenótipo , Fotossíntese , Plantas Geneticamente Modificadas , Plastídeos/metabolismo , Genética Reversa , Proteínas Ribossômicas/genética , Ribossomos/genética , Ribossomos/metabolismo , Plântula/embriologia , Plântula/genética , Plântula/crescimento & desenvolvimento , Plântula/fisiologia , Sementes/embriologia , Sementes/genética , Sementes/crescimento & desenvolvimento , Sementes/fisiologia
17.
Plant J ; 72(2): 249-60, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22762858

RESUMO

Previously, we identified HISTONE MONOUBIQUITINATION1 (HUB1) as an unconventional ubiquitin E3 ligase that is not involved in protein degradation but in the histone H2B modification that is implicated in transcriptional activation in plants. HUB1-mediated regulation of gene expression played a role in periodic and inducible processes such as the cell cycle, dormancy, flowering time and defense responses. Here, we determined the effects of the hub1-1 mutation on expression of a set of diurnally induced circadian clock genes identified from a comparative microarray analysis between the hub1-1 mutant and an HUB1 over-expression line. The hub1-1 mutation reduced the amplitudes of a number of induced clock gene expression peaks, as well as the HUB1-mediated histone H2BUb and H3K4Me3 marks associated with the coding regions, suggesting a role for HUB1 in facilitating transcriptional elongation in plants. Furthermore, double mutants between hub1-1 and elongata (elo) showed an embryo-lethal phenotype, indicating a synergistic genetic interaction. The double mutant embryos arrested at the torpedo stage, implying that together histone ubiquitination and acetylation marks are essential to activate expression of target genes in multiple pathways.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Relógios Circadianos/genética , Regulação da Expressão Gênica de Plantas/genética , Histonas/genética , Acetilação , Arabidopsis/embriologia , Arabidopsis/fisiologia , Cromatina/genética , Flores/embriologia , Flores/genética , Flores/fisiologia , Expressão Gênica , Perfilação da Expressão Gênica , Histona Acetiltransferases/genética , Histonas/metabolismo , Análise em Microsséries , Mutação , Fases de Leitura Aberta/genética , Folhas de Planta/embriologia , Folhas de Planta/genética , Folhas de Planta/fisiologia , Plantas Geneticamente Modificadas , RNA Mensageiro/genética , RNA de Plantas/genética , Plântula/embriologia , Plântula/genética , Plântula/fisiologia , Fatores de Tempo , Ativação Transcricional , Ubiquitina-Proteína Ligases/genética , Ubiquitinação
18.
Plant Cell ; 24(7): 2792-811, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22805435

RESUMO

The mitochondrial ATP synthase (F(1)F(o) complex) is an evolutionary conserved multimeric protein complex that synthesizes the main bulk of cytosolic ATP, but the regulatory mechanisms of the subunits are only poorly understood in plants. In yeast, the δ-subunit links the membrane-embedded F(o) part to the matrix-facing central stalk of F(1). We used genetic interference and an inhibitor to investigate the molecular function and physiological impact of the δ-subunit in Arabidopsis thaliana. Delta mutants displayed both male and female gametophyte defects. RNA interference of delta resulted in growth retardation, reduced ATP synthase amounts, and increased alternative oxidase capacity and led to specific long-term increases in Ala and Gly levels. By contrast, inhibition of the complex using oligomycin triggered broad metabolic changes, affecting glycolysis and the tricarboxylic acid cycle, and led to a successive induction of transcripts for alternative respiratory pathways and for redox and biotic stress-related transcription factors. We conclude that (1) the δ-subunit is essential for male gametophyte development in Arabidopsis, (2) a disturbance of the ATP synthase appears to lead to an early transition phase and a long-term metabolic steady state, and (3) the observed long-term adjustments in mitochondrial metabolism are linked to reduced growth and deficiencies in gametophyte development.


Assuntos
Arabidopsis/genética , Regulação da Expressão Gênica de Plantas/genética , Células Germinativas Vegetais/crescimento & desenvolvimento , Mitocôndrias/enzimologia , ATPases Mitocondriais Próton-Translocadoras/genética , Arabidopsis/embriologia , Arabidopsis/enzimologia , Arabidopsis/fisiologia , Respiração Celular , Cotilédone/embriologia , Cotilédone/enzimologia , Cotilédone/genética , Cotilédone/fisiologia , Regulação para Baixo/genética , Flores/embriologia , Flores/enzimologia , Flores/genética , Flores/fisiologia , Perfilação da Expressão Gênica , Células Germinativas Vegetais/citologia , Meristema/embriologia , Meristema/enzimologia , Meristema/genética , Meristema/fisiologia , Metaboloma , Mitocôndrias/genética , ATPases Mitocondriais Próton-Translocadoras/antagonistas & inibidores , ATPases Mitocondriais Próton-Translocadoras/metabolismo , Mutagênese Insercional , Oligomicinas/farmacologia , Análise de Sequência com Séries de Oligonucleotídeos , Estresse Oxidativo , Fenótipo , Infertilidade das Plantas , Plântula/embriologia , Plântula/enzimologia , Plântula/genética , Plântula/fisiologia , Transdução de Sinais , Transcriptoma
19.
Plant J ; 71(3): 503-16, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22679928

RESUMO

Interploidy crosses fail in many plant species due to abnormalities in endosperm development. In the inbreeding species Arabidopsis thaliana, both paternal and maternal excess interploidy crosses usually result in viable seed that exhibit parent-of-origin effects on endosperm development and final seed size. Paternal excess crosses result in extended proliferation of the endosperm and larger seeds, while conversely maternal excess crosses result in early endosperm cellularisation and smaller seeds. Investigations into the effect of parental gene dosage on seed development have revealed that MADS box transcription factors, particularly the AGAMOUS-like family, play important roles in controlling endosperm proliferation. The important crop genus Brassica contains self-incompatible outbreeding species and has a larger and more complex genome than the closely related Arabidopsis. Here we show that although Brassica oleracea displays strong parent-of-origin effects on seed development, triploid block due to lethal disruption of endosperm development was restricted to paternal excess, with maternal excess crosses yielding viable seed. In addition, transcriptome analyses of Brassica homologues of Arabidopsis genes linked to parent-of-origin effects revealed conservation of some mechanisms controlling aspects endosperm behaviour in the two species. However, there were also differences that may explain the failure of the paternal excess cross in B. oleracea.


Assuntos
Brassica/genética , Endosperma/genética , Dosagem de Genes/genética , Genoma de Planta/genética , Impressão Genômica/genética , Proteínas de Domínio MADS/genética , Arabidopsis/embriologia , Arabidopsis/genética , Arabidopsis/ultraestrutura , Brassica/embriologia , Brassica/ultraestrutura , Cruzamentos Genéticos , Endosperma/embriologia , Endosperma/ultraestrutura , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas/genética , Modelos Moleculares , Fenótipo , Proteínas de Plantas/genética , Plântula/embriologia , Plântula/genética , Plântula/ultraestrutura , Sementes/embriologia , Sementes/genética , Sementes/ultraestrutura , Fatores de Transcrição/genética , Triploidia
20.
Plant J ; 71(3): 427-42, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22429691

RESUMO

The transcription factor LEAFY COTYLEDON1 (LEC1) controls aspects of early embryogenesis and seed maturation in Arabidopsis thaliana. To identify components of the LEC1 regulon, transgenic plants were derived in which LEC1 expression was inducible by dexamethasone treatment. The cotyledon-like leaves and swollen root tips developed by these plants contained seed-storage compounds and resemble the phenotypes produced by increased auxin levels. In agreement with this, LEC1 was found to mediate up-regulation of the auxin synthesis gene YUCCA10. Auxin accumulated primarily in the elongation zone at the root-hypocotyl junction (collet). This accumulation correlates with hypocotyl growth, which is either inhibited in LEC1-induced embryonic seedlings or stimulated in the LEC1-induced long-hypocotyl phenotype, therefore resembling etiolated seedlings. Chromatin immunoprecipitation analysis revealed a number of phytohormone- and elongation-related genes among the putative LEC1 target genes. LEC1 appears to be an integrator of various regulatory events, involving the transcription factor itself as well as light and hormone signalling, especially during somatic and early zygotic embryogenesis. Furthermore, the data suggest non-embryonic functions for LEC1 during post-germinative etiolation.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Proteínas Estimuladoras de Ligação a CCAAT/genética , Regulação da Expressão Gênica de Plantas/genética , Reguladores de Crescimento de Planta/metabolismo , Transdução de Sinais/fisiologia , Ácido Abscísico/metabolismo , Arabidopsis/embriologia , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/ultraestrutura , Proteínas de Arabidopsis/metabolismo , Brassinosteroides/metabolismo , Proteínas Estimuladoras de Ligação a CCAAT/metabolismo , Perfilação da Expressão Gênica , Hipocótilo/embriologia , Hipocótilo/genética , Hipocótilo/crescimento & desenvolvimento , Hipocótilo/ultraestrutura , Ácidos Indolacéticos/metabolismo , Luz , Mutação , Motivos de Nucleotídeos , Análise de Sequência com Séries de Oligonucleotídeos , Componentes Aéreos da Planta/embriologia , Componentes Aéreos da Planta/genética , Componentes Aéreos da Planta/crescimento & desenvolvimento , Componentes Aéreos da Planta/ultraestrutura , Técnicas de Embriogênese Somática de Plantas , Plantas Geneticamente Modificadas , Plântula/embriologia , Plântula/genética , Plântula/crescimento & desenvolvimento , Plântula/ultraestrutura , Sementes/embriologia , Sementes/genética , Sementes/crescimento & desenvolvimento , Sementes/ultraestrutura , Regulação para Cima/genética
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA