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1.
Dokl Biochem Biophys ; 487(1): 269-271, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31559595

RESUMO

The freezing tolerance of Arabidopsis thaliana (L.) Heynh. was studied in relation to functioning of the ethylene signaling pathway. Constitutive freezing tolerance was compared in wild-type plants (ecotype Col-0) and ethylene-insensitive mutants etr1-1 and ein2-1. For the first time it was established that the ethylene-insensitive mutants had a 25-30% lower net photosynthesis rate, a decreased content of soluble sugars, and, as a result, a lower freezing tolerance. Our work provides evidence that the perception and transduction of ethylene signal are necessary for constitutive tolerance of Arabidopsis to low temperature.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Arabidopsis/fisiologia , Etilenos/metabolismo , Congelamento , Mutação , Receptores de Superfície Celular/genética , Arabidopsis/citologia , Arabidopsis/metabolismo , Transdução de Sinais/genética , Fatores de Tempo
2.
Dokl Biochem Biophys ; 486(1): 163-167, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31367812

RESUMO

The treatment of Arabidopsis thaliana plants with exogenous cytokinin (CK) followed by heat shock (HS) activated the expression of the genes for the plastid transcription machinery but adversely affected the plant viability. Abscisic acid (ABA), conversely, promoted maintaining the resistance to HS and had differentially affected different components of the plastid transcriptional complex. This hormone suppressed the accumulation of transcripts of PEP genes and the genes encoding PAP proteins, which are involved in DNA-RNA metabolism. However, it had no effect or activated the expression of NEP genes and PAP genes, which are involved in the redox regulation, as well as the genes encoding the stress-inducible trans-factor (SIG5) and the plastid transcription Ser/Thr protein kinase (cpCK2). Thus, for the adaptation of plants to elevated temperatures, both increase and decrease in the expression of the genes for the plastid transcriptional machinery with the involvement of various regulatory systems, including phytohormones, are equally significant.


Assuntos
Ácido Abscísico/farmacologia , Arabidopsis/efeitos dos fármacos , Citocininas/farmacologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Resposta ao Choque Térmico/genética , Plastídeos/genética , Transcrição Genética/efeitos dos fármacos , Arabidopsis/citologia , Arabidopsis/genética , Arabidopsis/fisiologia , Resposta ao Choque Térmico/efeitos dos fármacos , Plastídeos/efeitos dos fármacos
3.
Int J Mol Sci ; 20(11)2019 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-31195605

RESUMO

The actin cytoskeleton is involved in regulating stomatal movement, which forms distinct actin arrays within guard cells of stomata with different apertures. How those actin arrays are formed and maintained remains largely unexplored. Elucidation of the dynamic behavior of differently oriented actin filaments in guard cells will enhance our understanding in this regard. Here, we initially developed a program called 'guard cell microfilament analyzer' (GCMA) that enables the selection of individual actin filaments and analysis of their orientations semiautomatically in guard cells. We next traced the dynamics of individual actin filaments and performed careful quantification in open and closed stomata. We found that de novo nucleation of actin filaments occurs at both dorsal and ventral sides of guard cells from open and closed stomata. Interestingly, most of the nucleated actin filaments elongate radially and longitudinally in open and closed stomata, respectively. Strikingly, radial filaments tend to form bundles whereas longitudinal filaments tend to be removed by severing and depolymerization in open stomata. By contrast, longitudinal filaments tend to form bundles that are severed less frequently in closed stomata. These observations provide insights into the formation and maintenance of distinct actin arrays in guard cells in stomata of different apertures.


Assuntos
Citoesqueleto de Actina/metabolismo , Arabidopsis/citologia , Arabidopsis/metabolismo , Estômatos de Plantas/citologia , Estômatos de Plantas/metabolismo , Actinas/metabolismo , Ritmo Circadiano/fisiologia , Polimerização
4.
BMC Biol ; 17(1): 38, 2019 05 09.
Artigo em Inglês | MEDLINE | ID: mdl-31072374

RESUMO

BACKGROUND: Many methods have been developed to quantify cell shape in 2D in tissues. For instance, the analysis of epithelial cells in Drosophila embryogenesis or jigsaw puzzle-shaped pavement cells in plant epidermis has led to the development of numerous quantification methods that are applied to 2D images. However, proper extraction of 2D cell contours from 3D confocal stacks for such analysis can be problematic. RESULTS: We developed a macro in ImageJ, SurfCut, with the goal to provide a user-friendly pipeline specifically designed to extract epidermal cell contour signals, segment cells in 2D and analyze cell shape. As a reference point, we compared our output to that obtained with MorphoGraphX (MGX). While both methods differ in the approach used to extract the layer of signal, they output comparable results for tissues with shallow curvature, such as pavement cell shape in cotyledon epidermis (as quantified with PaCeQuant). SurfCut was however not appropriate for cell or tissue samples with high curvature, as evidenced by a significant bias in shape and area quantification. CONCLUSION: We provide a new ImageJ pipeline, SurfCut, that allows the extraction of cell contours from 3D confocal stacks. SurfCut and MGX have complementary advantages: MGX is well suited for curvy samples and more complex analyses, up to computational cell-based modeling on real templates; SurfCut is well suited for rather flat samples, is simple to use, and has the advantage to be easily automated for batch analysis of images in ImageJ. The combination of these two methods thus provides an ideal suite of tools for cell contour extraction in most biological samples, whether 3D precision or high-throughput analysis is the main priority.


Assuntos
Arabidopsis/citologia , Forma Celular , Imagem Tridimensional/métodos , Imagem Tridimensional/instrumentação , Microscopia Confocal
5.
Plant Cell Physiol ; 60(8): 1855-1870, 2019 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-31135031

RESUMO

Formins are evolutionarily conserved eukaryotic proteins engaged in actin nucleation and other aspects of cytoskeletal organization. Angiosperms have two formin clades with multiple paralogs; typical plant Class I formins are integral membrane proteins that can anchor cytoskeletal structures to membranes. For the main Arabidopsis housekeeping Class I formin, FH1 (At3g25500), plasmalemma localization was documented in heterologous expression and overexpression studies. We previously showed that loss of FH1 function increases cotyledon epidermal pavement cell shape complexity via modification of actin and microtubule organization and dynamics. Here, we employ transgenic Arabidopsis expressing green fluorescent protein-tagged FH1 (FH1-GFP) from its native promoter to investigate in vivo behavior of this formin using advanced microscopy techniques. The fusion protein is functional, since its expression complements the fh1 loss-of-function mutant phenotype. Accidental overexpression of FH1-GFP results in a decrease in trichome branch number, while fh1 mutation has the opposite effect, indicating a general role of this formin in controlling cell shape complexity. Consistent with previous reports, FH1-GFP associates with membranes. However, the protein exhibits surprising actin- and secretory pathway-dependent dynamic localization and relocates between cellular endomembranes and the plasmalemma during cell division and differentiation in root tissues, with transient tonoplast localization at the transition/elongation zones border. FH1-GFP also accumulates in actin-rich regions of cortical cytoplasm and associates with plasmodesmata in both the cotyledon epidermis and root tissues. Together with previous reports from metazoan systems, this suggests that formins might have a shared (ancestral or convergent) role at cell-cell junctions.


Assuntos
Arabidopsis/metabolismo , Raízes de Plantas/metabolismo , Plasmodesmos/fisiologia , Arabidopsis/citologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Citoesqueleto/genética , Citoesqueleto/metabolismo , Raízes de Plantas/citologia
6.
Nat Genet ; 51(5): 786-792, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30988512

RESUMO

Precise control of plant stem cell proliferation is necessary for the continuous and reproducible development of plant organs1,2. The peptide ligand CLAVATA3 (CLV3) and its receptor protein kinase CLAVATA1 (CLV1) maintain stem cell homeostasis within a deeply conserved negative feedback circuit1,2. In Arabidopsis, CLV1 paralogs also contribute to homeostasis, by compensating for the loss of CLV1 through transcriptional upregulation3. Here, we show that compensation4,5 operates in diverse lineages for both ligands and receptors, but while the core CLV signaling module is conserved, compensation mechanisms have diversified. Transcriptional compensation between ligand paralogs operates in tomato, facilitated by an ancient gene duplication that impacted the domestication of fruit size. In contrast, we found little evidence for transcriptional compensation between ligands in Arabidopsis and maize, and receptor compensation differs between tomato and Arabidopsis. Our findings show that compensation among ligand and receptor paralogs is critical for stem cell homeostasis, but that diverse genetic mechanisms buffer conserved developmental programs.


Assuntos
Meristema/citologia , Meristema/genética , Desenvolvimento Vegetal/genética , Arabidopsis/citologia , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/genética , Proliferação de Células/genética , Evolução Molecular , Regulação da Expressão Gênica de Plantas , Redes Reguladoras de Genes , Genes de Plantas , Peptídeos e Proteínas de Sinalização Intercelular/genética , Ligantes , Lycopersicon esculentum/citologia , Lycopersicon esculentum/genética , Lycopersicon esculentum/crescimento & desenvolvimento , Modelos Genéticos , Mutação , Plantas Geneticamente Modificadas , Proteínas Serina-Treonina Quinases/genética , Transdução de Sinais/genética , Células-Tronco/citologia , Zea mays/citologia , Zea mays/genética , Zea mays/crescimento & desenvolvimento
7.
Chem Commun (Camb) ; 55(33): 4841-4844, 2019 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-30950467

RESUMO

A molecular probe with aggregation-induced phosphorescence (AIP) properties for calcium ion-specific detection and imaging in vivo was designed. The long-lived phosphorescence caused by calcium-triggered aggregation enables establishment of a first time-gated detection method for calcium ions and long-term imaging in Arabidopsis thaliana.


Assuntos
Arabidopsis/metabolismo , Cálcio/metabolismo , Sondas Moleculares/metabolismo , Arabidopsis/citologia , Luminescência , Microscopia Eletrônica de Varredura
8.
BMC Plant Biol ; 19(1): 151, 2019 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-30999851

RESUMO

BACKGROUND: Grafting is a technique widely used in horticulture. The processes involved in grafting are diverse, and the technique is commonly employed in studies focusing on the mechanisms that regulate cell differentiation or response of plants to abiotic stress. Information on the changes in the composition of the cell wall that occur during the grafting process is scarce. Therefore, this study was carried out for analyzing the composition of the cell wall using Arabidopsis hypocotyls as an example. During the study, the formation of a layer that covers the surface of the graft union was observed. So, this study also aimed to describe the histological and cellular changes that accompany autografting of Arabidopsis hypocotyls and to perform preliminary chemical and structural analyses of extracellular material that seals the graft union. RESULTS: During grafting, polyphenolic and lipid compounds were detected, along with extracellular deposition of carbohydrate/protein material. The spatiotemporal changes observed in the structure of the extracellular material included the formation of a fibrillar network, polymerization of the fibrillar network into a membranous layer, and the presence of bead-like structures on the surface of cells in established graft union. These bead-like structures appeared either "closed" or "open". Only three cell wall epitopes, namely: LM19 (un/low-methyl-esterified homogalacturonan), JIM11, and JIM20 (extensins), were detected abundantly on the cut surfaces that made the adhesion plane, as well as in the structure that covered the graft union and in the bead-like structures, during the subsequent stages of regeneration. CONCLUSIONS: To the best of our knowledge, this is the first report on the composition and structure of the extracellular material that gets deposited on the surface of graft union during Arabidopsis grafting. The results showed that unmethyl-esterified homogalacturonan and extensins are together involved in the adhesion of scion and stock, as well as taking part in sealing the graft union. The extracellular material is of importance not only due to the potential pectin-extensin interaction but also due to its origin. The findings presented here implicate a need for studies with biochemical approach for a detailed analysis of the composition and structure of the extracellular material.


Assuntos
Arabidopsis/fisiologia , Glicoproteínas/metabolismo , Pectinas/metabolismo , Proteínas de Plantas/metabolismo , Arabidopsis/anatomia & histologia , Arabidopsis/citologia , Arabidopsis/ultraestrutura , Parede Celular/metabolismo , Epitopos/metabolismo , Esterificação , Hipocótilo/citologia , Hipocótilo/fisiologia , Hipocótilo/ultraestrutura
9.
Mol Plant ; 12(5): 648-660, 2019 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-31004836

RESUMO

Cells of eukaryotic multicellular organisms have inherent heterogeneity. Recent advances in single-cell gene expression studies enable us to explore transcriptional regulation in dynamic development processes and highly heterogeneous cell populations. In this study, using a high-throughput single-cell RNA-sequencing assay, we found that the cells in Arabidopsis root are highly heterogeneous in their transcriptomes. A total of 24 putative cell clusters and the cluster-specific marker genes were identified. The spatial distribution and temporal ordering of the individual cells at different developmental stages illustrate their hierarchical structures and enable the reconstruction of continuous differentiation trajectory of root development. Moreover, we found that each root cell cluster exhibits distinct patterns of ion assimilation and hormonal responses. Collectively, our study reveals a high degree of heterogeneity of root cells and identifies the expression signatures of intermediate states during root cell differentiation at single-cell resolution. We also established a web server (http://wanglab.sippe.ac.cn/rootatlas/) to facilitate the use of the datasets generated in this study.


Assuntos
Arabidopsis/crescimento & desenvolvimento , Arabidopsis/genética , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/genética , Análise de Sequência de RNA , Análise de Célula Única , Arabidopsis/citologia , Arabidopsis/metabolismo , Citocininas/metabolismo , Perfilação da Expressão Gênica , Genes de Plantas/genética , Reguladores de Crescimento de Planta/metabolismo , Raízes de Plantas/citologia
10.
Radiat Res ; 191(6): 556-565, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31017526

RESUMO

Radiation-induced bystander effects (RIBE) entail a cascade of bystander signals produced by the hit cells to the neighboring cells to regulate various biological processes including DNA damage repair. However, there is little clarity regarding the effect of radiation-targeted volume (hit cell amount) on the DNA repair potential of the bystander cells. This is especially important to understand in the context of the whole organism, where the target usually consists of multiple types of cells/tissues. To address this question, model plant Arabidopsis thaliana was locally irradiated, and the DNA repair potential of bystander root-tip cells was assessed based on their radioresistance to subsequent high-dose radiation, i.e. radioadaptive responses (RAR). We found that X-ray irradiation of the aerial parts (AP) of A. thaliana seedlings (5 Gy) initiated RAR in the root-tip cells, which exhibited an alleviated repression of root growth and root cell division, and reduced amount of DNA strand breaks. We also observed an improvement in the repair efficiency of the homologous recombination (HR) and non-homologous end joining (NHEJ) pathways in the bystander root tip cells. We further expanded the X-ray targeted volume to include the aerial parts with upper parts of the primary root and compared it with X-ray irradiated aerial parts alone. Comparative analysis revealed that RAR for these end points either disappeared or decreased; specifically, the repair efficiency of HR was significantly reduced, indicating that radiation-targeted volume negatively modulates the bystander DNA repair potential. In contrast, X-ray irradiation of upper part of the primary root alone did not induce RAR of the root tip cells. Thus, we propose that additional X-ray irradiation of upper part of the primary root reduces the bystander DNA repair potential, possibly by selectively disturbing the transport of bystander signals responsible for HR repair.


Assuntos
Arabidopsis/genética , Arabidopsis/efeitos da radiação , Efeito Espectador/genética , Efeito Espectador/efeitos da radiação , Reparo do DNA/efeitos da radiação , Arabidopsis/citologia , Dano ao DNA , Raízes de Plantas/genética , Raízes de Plantas/efeitos da radiação , Plântula/genética , Plântula/efeitos da radiação , Transdução de Sinais/efeitos da radiação , Raios X/efeitos adversos
11.
Int J Mol Sci ; 20(7)2019 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-30987084

RESUMO

Increasing usage of gold nanoparticles (AuNPs) in different industrial areas inevitably leads to their release into the environment. Thus, living organisms, including plants, may be exposed to a direct contact with nanoparticles (NPs). Despite the growing amount of research on this topic, our knowledge about NPs uptake by plants and their influence on different developmental processes is still insufficient. The first physical barrier for NPs penetration to the plant body is a cell wall which protects cytoplasm from external factors and environmental stresses. The absence of a cell wall may facilitate the internalization of various particles including NPs. Our studies have shown that AuNPs, independently of their surface charge, did not cross the cell wall of Arabidopsis thaliana (L.) roots. However, the research carried out with using light and transmission electron microscope revealed that AuNPs with different surface charge caused diverse changes in the root's histology and ultrastructure. Therefore, we verified whether this is only the wall which protects cells against particles penetration and for this purpose we used protoplasts culture. It has been shown that plasma membrane (PM) is not a barrier for positively charged (+) AuNPs and negatively charged (-) AuNPs, which passage to the cell.


Assuntos
Arabidopsis/citologia , Arabidopsis/crescimento & desenvolvimento , Nanopartículas Metálicas/química , Raízes de Plantas/citologia , Raízes de Plantas/crescimento & desenvolvimento , Protoplastos/metabolismo , Arabidopsis/ultraestrutura , Parede Celular/metabolismo , Nanopartículas Metálicas/ultraestrutura , Raízes de Plantas/ultraestrutura , Protoplastos/citologia , Protoplastos/ultraestrutura , Propriedades de Superfície
12.
Nat Commun ; 10(1): 1744, 2019 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-30988311

RESUMO

SCM, a leucine-rich repeat receptor-like kinase, is required for root epidermal cells to appropriately interpret their location and generate the proper cell-type pattern during Arabidopsis root development. Here, via a screen for scm-like mutants we describe a new allele of the QKY gene. We find that QKY is required for the appropriate spatial expression of several epidermal cell fate regulators in a similar manner as SCM in roots, and that QKY and SCM are necessary for the efficient movement of CPC between epidermal cells. We also show that turnover of SCM is mediated by a vacuolar degradation pathway triggered by ubiquitination, and that QKY prevents this SCM ubiquitination through their physical interaction. These results suggest that QKY stabilizes SCM through interaction, and this complex facilitates CPC movement between the epidermal cells to help establish the cell-type pattern in the Arabidopsis root epidermis.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/citologia , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Morfogênese , Epiderme Vegetal/citologia , Epiderme Vegetal/metabolismo , Raízes de Plantas/citologia , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Proteínas Proto-Oncogênicas c-myb/metabolismo , Receptores Proteína Tirosina Quinases/genética , Receptores Proteína Tirosina Quinases/metabolismo , Transdução de Sinais
13.
Nat Commun ; 10(1): 1755, 2019 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-30988453

RESUMO

Mitosis and meiosis both rely on cohesin, which embraces the sister chromatids and plays a crucial role for the faithful distribution of chromosomes to daughter cells. Prior to the cleavage by Separase at anaphase onset, cohesin is largely removed from chromosomes by the non-proteolytic action of WINGS APART-LIKE (WAPL), a mechanism referred to as the prophase pathway. To prevent the premature loss of sister chromatid cohesion, WAPL is inhibited in early mitosis by Sororin. However, Sororin homologs have only been found to function as WAPL inhibitors during mitosis in vertebrates and Drosophila. Here we show that SWITCH 1/DYAD defines a WAPL antagonist that acts in meiosis of Arabidopsis. Crucially, SWI1 becomes dispensable for sister chromatid cohesion in the absence of WAPL. Despite the lack of any sequence similarities, we found that SWI1 is regulated and functions in a similar manner as Sororin hence likely representing a case of convergent molecular evolution across the eukaryotic kingdom.


Assuntos
Proteínas de Arabidopsis/antagonistas & inibidores , Proteínas de Arabidopsis/fisiologia , Arabidopsis/genética , Proteínas de Ciclo Celular/antagonistas & inibidores , Proteínas de Ciclo Celular/fisiologia , Cromátides/metabolismo , Meiose/fisiologia , Proteínas Nucleares/fisiologia , Arabidopsis/citologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Evolução Molecular , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo
14.
Nature ; 568(7751): 240-243, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30944466

RESUMO

The plant hormone auxin has crucial roles in almost all aspects of plant growth and development. Concentrations of auxin vary across different tissues, mediating distinct developmental outcomes and contributing to the functional diversity of auxin. However, the mechanisms that underlie these activities are poorly understood. Here we identify an auxin signalling mechanism, which acts in parallel to the canonical auxin pathway based on the transport inhibitor response1 (TIR1) and other auxin receptor F-box (AFB) family proteins (TIR1/AFB receptors)1,2, that translates levels of cellular auxin to mediate differential growth during apical-hook development. This signalling mechanism operates at the concave side of the apical hook, and involves auxin-mediated C-terminal cleavage of transmembrane kinase 1 (TMK1). The cytosolic and nucleus-translocated C terminus of TMK1 specifically interacts with and phosphorylates two non-canonical transcriptional repressors of the auxin or indole-3-acetic acid (Aux/IAA) family (IAA32 and IAA34), thereby regulating ARF transcription factors. In contrast to the degradation of Aux/IAA transcriptional repressors in the canonical pathway, the newly identified mechanism stabilizes the non-canonical IAA32 and IAA34 transcriptional repressors to regulate gene expression and ultimately inhibit growth. The auxin-TMK1 signalling pathway originates at the cell surface, is triggered by high levels of auxin and shares a partially overlapping set of transcription factors with the TIR1/AFB signalling pathway. This allows distinct interpretations of different concentrations of cellular auxin, and thus enables this versatile signalling molecule to mediate complex developmental outcomes.


Assuntos
Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Ácidos Indolacéticos/metabolismo , Reguladores de Crescimento de Planta/metabolismo , Transdução de Sinais , Sequência de Aminoácidos , Arabidopsis/citologia , Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas F-Box/metabolismo , Ácidos Indolacéticos/antagonistas & inibidores , Mutação , Reguladores de Crescimento de Planta/antagonistas & inibidores , Ligação Proteica , Receptores de Superfície Celular/metabolismo
15.
PLoS Comput Biol ; 15(4): e1006896, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30998674

RESUMO

Polar auxin transport lies at the core of many self-organizing phenomena sustaining continuous plant organogenesis. In angiosperms, the shoot apical meristem is a potentially unique system in which the two main modes of auxin-driven patterning-convergence and canalization-co-occur in a coordinated manner and in a fully three-dimensional geometry. In the epidermal layer, convergence points form, from which auxin is canalized towards inner tissue. Each of these two patterning processes has been extensively investigated separately, but the integration of both in the shoot apical meristem remains poorly understood. We present here a first attempt of a three-dimensional model of auxin-driven patterning during phyllotaxis. We base our simulations on a biochemically plausible mechanism of auxin transport proposed by Cieslak et al. (2015) which generates both convergence and canalization patterns. We are able to reproduce most of the dynamics of PIN1 polarization in the meristem, and we explore how the epidermal and inner cell layers act in concert during phyllotaxis. In addition, we discuss the mechanism by which initiating veins connect to the already existing vascular system.


Assuntos
Transporte Biológico/fisiologia , Ácidos Indolacéticos/metabolismo , Meristema/metabolismo , Modelos Biológicos , Células Vegetais , Arabidopsis/citologia , Arabidopsis/metabolismo , Arabidopsis/fisiologia , Proteínas de Arabidopsis/metabolismo , Biologia Computacional , Simulação por Computador , Células Vegetais/metabolismo , Células Vegetais/fisiologia , Folhas de Planta/citologia , Caules de Planta/citologia
16.
Plant Sci ; 280: 12-17, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30823989

RESUMO

It is now well established that sphingoid Long Chain Bases (LCBs) are crucial mediators of programmed cell death. In plants, the mycotoxin fumonisin B1 (FB1) produced by the necrotrophic fungus Fusarium moniliforme disrupts the sphingolipid biosynthesis pathway by inhibiting the ceramide synthase leading to an increase in the amount of phytosphingosine (PHS) and dihydrosphingosine (DHS), the two major LCBs in Arabidopsis thaliana. To date, the signaling pathway involved in FB1-induced cell death remains largely uncharacterized. It is also well acknowledged that plant proteases such as papain-like cysteine protease are largely involved in plant immunity. Here, we show that the papain-like cysteine protease RD21 (responsive-to-desiccation-21) is activated in response to PHS and FB1 in Arabidopsis cultured cells and leaves, respectively. Using two allelic null mutants of RD21, and two different PCD bioassays, we demonstrate that the protein acts as a negative regulator of FB1-induced cell death in Arabidopsis.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/citologia , Arabidopsis/metabolismo , Morte Celular/fisiologia , Papaína/metabolismo , Esfingolipídeos/metabolismo , Proteínas de Arabidopsis/genética , Morte Celular/genética , Regulação da Expressão Gênica de Plantas/genética , Regulação da Expressão Gênica de Plantas/fisiologia , Transdução de Sinais/genética , Transdução de Sinais/fisiologia
17.
Nucleic Acids Res ; 47(10): 5001-5015, 2019 06 04.
Artigo em Inglês | MEDLINE | ID: mdl-30892623

RESUMO

Circadian clock coordinates numerous plant growth and developmental processes including cell elongation in the hypocotyl, whether or not it modulates cell proliferation is largely unknown. Here we have found that Pseudo Response Regulators (PRRs), essential components of circadian core oscillators, affect root meristem cell proliferation mediated by Target Of Rapamycin (TOR) signaling. The null mutants of PRRs display much reduced sensitivities to sugar-activated TOR signaling. We have subsequently identified Tandem Zinc Finger 1, encoding a processing body localized RNA-binding protein, as a direct target repressed by PRRs in mediating TOR signaling. Multiple lines of biochemical and genetic evidence have demonstrated that TZF1 acts downstream of PRRs to attenuate TOR signaling. Furthermore, TZF1 could directly bind TOR mRNA via its tandem zinc finger motif to affect TOR mRNA stability. Our findings support a notion that PRR-TZF1-TOR molecular axis modulates root meristem cell proliferation by integrating both transcriptional and post-transcriptional regulatory mechanisms.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Proliferação de Células/genética , Fosfatidilinositol 3-Quinases/genética , Raízes de Plantas/genética , Proteínas Repressoras/genética , Fatores de Transcrição/genética , Arabidopsis/citologia , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Relógios Circadianos , Regulação da Expressão Gênica de Plantas , Meristema/citologia , Meristema/genética , Meristema/metabolismo , Mutação , Fosfatidilinositol 3-Quinases/metabolismo , Raízes de Plantas/citologia , Raízes de Plantas/metabolismo , Proteínas Repressoras/metabolismo , Transdução de Sinais/genética , Fatores de Transcrição/metabolismo
18.
Plant Cell Physiol ; 60(6): 1296-1303, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30892660

RESUMO

Plant roots secrete various substances with diverse functions against both plants and microbes in the rhizosphere. A major secretory substance is root-cap mucilage, whose functions have been well characterized, albeit mainly in crops. However, little is currently known about the developmental mechanisms of root-cap mucilage. Here, we show the accumulation and extrusion of root-cap mucilage in Arabidopsis. We found propidium iodide (PI) stainable structures between the plasma membrane and cell wall in the sixth layer of columella cells (c6) from the quiescent center. Ruthenium red staining and PI staining with calcium ions suggested that the structure comprises in part pectin polysaccharides. Electron microscopy revealed that the structure had a meshwork of electron-dense filaments that resembled periplasmic mucilage in other plants. In the c6 cells, we also observed many large vesicles with denser meshwork filaments to periplasmic mucilage, which likely mediate the transport of mucilage components. Extruded mucilage was observed outside a partially degraded cell wall in the c7 cells. Moreover, we found that the Class IIB NAC transcription factors BEARSKIN1 (BRN1) and BRN2, which are known to regulate the terminal differentiation of columella cells, were required for the efficient accumulation of root-cap mucilage in Arabidopsis. Taken together, our findings reveal the accumulation of and dynamic changes in periplasmic mucilage during columella cell development in Arabidopsis.


Assuntos
Arabidopsis/crescimento & desenvolvimento , Periplasma/metabolismo , Mucilagem Vegetal/metabolismo , Coifa/metabolismo , Arabidopsis/citologia , Arabidopsis/metabolismo , Arabidopsis/ultraestrutura , Corantes , Microscopia Eletrônica de Transmissão , Coifa/citologia , Coifa/ultraestrutura , Propídio
19.
PLoS Genet ; 15(2): e1007988, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30742619

RESUMO

Cells in organ primordia undergo active proliferation at an early stage to generate sufficient number, before exiting proliferation and entering differentiation. However, how the actively proliferating cells are developmentally reprogrammed to acquire differentiation potential during organ maturation is unclear. Here, we induced a microRNA-resistant form of TCP4 at various developmental stages of Arabidopsis leaf primordium that lacked the activity of TCP4 and its homologues and followed its effect on growth kinematics. By combining this with spatio-temporal gene expression analysis, we show that TCP4 commits leaf cells within the transition zone to exit proliferation and enter differentiation. A 24-hour pulse of TCP4 activity was sufficient to impart irreversible differentiation competence to the actively dividing cells. A combination of biochemical and genetic analyses revealed that TCP4 imparts differentiation competence by promoting auxin response as well as by directly activating HAT2, a HD-ZIP II transcription factor-encoding gene that also acts downstream to auxin response. Our study offers a molecular link between the two major organ maturation factors, CIN-like TCPs and HD-ZIP II transcription factors and explains how TCP activity restricts the cell number and final size in a leaf.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/citologia , Arabidopsis/metabolismo , Ácidos Indolacéticos/metabolismo , Fatores de Transcrição/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Fenômenos Biomecânicos , Contagem de Células , Diferenciação Celular/genética , Diferenciação Celular/fisiologia , Proliferação de Células/genética , Proliferação de Células/fisiologia , Tamanho Celular , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Reguladores de Crescimento de Planta/metabolismo , Folhas de Planta/citologia , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Plantas Geneticamente Modificadas , Fatores de Transcrição/genética
20.
Analyst ; 144(7): 2320-2326, 2019 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-30714606

RESUMO

Understanding the dynamic status of intracellular cysteine that responds to the stimulation of external oxidative stress is of great importance to mechanistic studies of cysteine related biology and medicine. However, due to the interference of structural similarity and comparable reactivity of other bio-thiols under physiological conditions, it is exceedingly challenging to develop fluorescent probes with excellent selectivity and sensitivity for the visualization of cysteine activities in an intricate biological context. Herein, we report a new fluorescent probe with an extended coumarin fluorophore, CyP, which displays favorable advantages for intracellular cysteine detection in living cells, and enables effective in vivo visualization of endogenous cysteine activities under external stimuli in live nematodes and plants. In addition, the dynamic changes of the intracellular cysteine pool after exposure to cadmium-induced oxidative stress have been successfully monitored by using this probe in Arabidopsis thaliana, thus providing a valuable diagnostic tool to investigate cysteine functions in a variety of biological phenomena.


Assuntos
Cisteína/metabolismo , Espaço Intracelular/metabolismo , Estresse Oxidativo , Animais , Arabidopsis/citologia , Cádmio/toxicidade , Sobrevivência Celular , Cumarínicos/química , Cumarínicos/metabolismo , Desenho de Drogas , Corantes Fluorescentes/química , Corantes Fluorescentes/metabolismo , Células HeLa , Humanos , Espaço Intracelular/efeitos dos fármacos , Nematoides/citologia , Estresse Oxidativo/efeitos dos fármacos
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