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1.
Curr Opin Plant Biol ; 51: 105-113, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31349107

RESUMO

Brassinosteroids (BRs) are essential hormones for plant growth and development that are perceived at the plasma membrane by a group of Leucine-Rich Repeat Receptor-Like Kinases (LRR-RLKs) of the BRASSINOSTEROID INSENSITIVE 1 (BRI1) family. The BRI1 receptor was first discovered by genetic screenings based on the dwarfism of BR-deficient plants. There are three BRI1 homologs, named BRI1-like 1, 2 and 3 (BRLs), yet only BRL1 and BRL3 behave as functional BR receptors. Whereas the BRI1 pathway operates in the majority of cells to promote growth, BRL receptor signaling operates under specific spatiotemporal constraints. Despite a wealth of information on the BRI1 pathway, data on specific BRL pathways and their biological relevance is just starting to emerge. Here, we systematically compare BRLs with BRI1 to identify any differences that could account for specific receptor functions. Understanding how vascular and cell-specific BRL receptors orchestrate plant development and adaptation to the environment will help shed light on membrane signaling and cell communication in plants, while opening up novel possibilities to improve stress adaptation without penalizing growth.

2.
Development ; 146(5)2019 03 14.
Artigo em Inglês | MEDLINE | ID: mdl-30872266

RESUMO

Brassinosteroids (BRs) are steroid hormones that are essential for plant growth and development. These hormones control the division, elongation and differentiation of various cell types throughout the entire plant life cycle. Our current understanding of the BR signaling pathway has mostly been obtained from studies using Arabidopsis thaliana as a model. In this context, the membrane steroid receptor BRI1 (BRASSINOSTEROID INSENSITIVE 1) binds directly to the BR ligand, triggering a signal cascade in the cytoplasm that leads to the transcription of BR-responsive genes that drive cellular growth. However, recent studies of the primary root have revealed distinct BR signaling pathways in different cell types and have highlighted cell-specific roles for BR signaling in controlling adaptation to stress. In this Review, we summarize our current knowledge of the spatiotemporal control of BR action in plant growth and development, focusing on BR functions in primary root development and growth, in stem cell self-renewal and death, and in plant adaption to environmental stress.


Assuntos
Aclimatação , Arabidopsis/fisiologia , Brassinosteroides/metabolismo , Transdução de Sinais , Estresse Fisiológico , Proteínas de Arabidopsis/fisiologia , Diferenciação Celular , Regulação da Expressão Gênica de Plantas , Ligantes , Desenvolvimento Vegetal , Reguladores de Crescimento de Planta/fisiologia , Raízes de Plantas/fisiologia , Plantas Geneticamente Modificadas/fisiologia , Proteínas Quinases/fisiologia
3.
Plant J ; 98(6): 1145-1156, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30809923

RESUMO

Root analysis is essential for both academic and agricultural research. Despite the great advances in root phenotyping and imaging, calculating root length is still performed manually and involves considerable amounts of labor and time. To overcome these limitations, we developed MyROOT, a software for the semiautomatic quantification of root growth of seedlings growing directly on agar plates. Our method automatically determines the scale from the image of the plate, and subsequently measures the root length of the individual plants. To this aim, MyROOT combines a bottom-up root tracking approach with a hypocotyl detection algorithm. At the same time as providing accurate root measurements, MyROOT also significantly minimizes the user intervention required during the process. Using Arabidopsis, we tested MyROOT with seedlings from different growth stages and experimental conditions. When comparing the data obtained from this software with that of manual root measurements, we found a high correlation between both methods (R2  = 0.997). When compared with previous developed software with similar features (BRAT and EZ-Rhizo), MyROOT offered an improved accuracy for root length measurements. Therefore, MyROOT will be of great use to the plant science community by permitting high-throughput root length measurements while saving both labor and time.

4.
Nat Commun ; 9(1): 4680, 2018 11 08.
Artigo em Inglês | MEDLINE | ID: mdl-30409967

RESUMO

Drought represents a major threat to food security. Mechanistic data describing plant responses to drought have been studied extensively and genes conferring drought resistance have been introduced into crop plants. However, plants with enhanced drought resistance usually display lower growth, highlighting the need for strategies to uncouple drought resistance from growth. Here, we show that overexpression of BRL3, a vascular-enriched member of the brassinosteroid receptor family, can confer drought stress tolerance in Arabidopsis. Whereas loss-of-function mutations in the ubiquitously expressed BRI1 receptor leads to drought resistance at the expense of growth, overexpression of BRL3 receptor confers drought tolerance without penalizing overall growth. Systematic analyses reveal that upon drought stress, increased BRL3 triggers the accumulation of osmoprotectant metabolites including proline and sugars. Transcriptomic analysis suggests that this results from differential expression of genes in the vascular tissues. Altogether, this data suggests that manipulating BRL3 expression could be used to engineer drought tolerant crops.


Assuntos
Arabidopsis/fisiologia , Secas , Desenvolvimento Vegetal , Feixe Vascular de Plantas/metabolismo , Receptores de Superfície Celular/metabolismo , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Metaboloma , Mutação/genética , Pressão Osmótica , Desenvolvimento Vegetal/genética , Raízes de Plantas/genética , Raízes de Plantas/fisiologia , Plantas Geneticamente Modificadas , Estresse Fisiológico/genética , Transcrição Genética , Tropismo
5.
Mol Syst Biol ; 14(1): e7687, 2018 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-29321184

RESUMO

Plant roots grow due to cell division in the meristem and subsequent cell elongation and differentiation, a tightly coordinated process that ensures growth and adaptation to the changing environment. How the newly formed cells decide to stop elongating becoming fully differentiated is not yet understood. To address this question, we established a novel approach that combines the quantitative phenotypic variability of wild-type Arabidopsis roots with computational data from mathematical models. Our analyses reveal that primary root growth is consistent with a Sizer mechanism, in which cells sense their length and stop elongating when reaching a threshold value. The local expression of brassinosteroid receptors only in the meristem is sufficient to set this value. Analysis of roots insensitive to BR signaling and of roots with gibberellin biosynthesis inhibited suggests distinct roles of these hormones on cell expansion termination. Overall, our study underscores the value of using computational modeling together with quantitative data to understand root growth.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/crescimento & desenvolvimento , Modelos Teóricos , Arabidopsis/citologia , Arabidopsis/metabolismo , Diferenciação Celular/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Giberelinas/farmacologia , Meristema/citologia , Meristema/crescimento & desenvolvimento , Meristema/metabolismo , Fenótipo , Reguladores de Crescimento de Planta/farmacologia , Raízes de Plantas/citologia , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo
6.
J Cell Sci ; 131(2)2018 01 29.
Artigo em Inglês | MEDLINE | ID: mdl-29242230

RESUMO

Stem cell regeneration is crucial for both cell turnover and tissue healing in multicellular organisms. In Arabidopsis roots, a reduced group of cells known as the quiescent center (QC) act as a cell reservoir for surrounding stem cells during both normal growth and in response to external damage. Although cells of the QC have a very low mitotic activity, plant hormones such as brassinosteroids (BRs) can promote QC divisions. Here, we used a tissue-specific strategy to investigate the spatial signaling requirements of BR-mediated QC divisions. We generated stem cell niche-specific receptor knockout lines by placing an artificial microRNA against BRI1 (BRASSINOSTEROID INSENSITIVE 1) under the control of the QC-specific promoter WOX5. Additionally, QC-specific knock-in lines for BRI1 and its downstream transcription factor BES1 (BRI1-EMS-SUPPRESOR1) were also created using the WOX5 promoter. By analyzing the roots of these lines, we show that BES1-mediated signaling cell-autonomously promotes QC divisions, that BRI1 is essential for sensing nearby inputs and triggering QC divisions and that DNA damage promotes BR-dependent paracrine signaling in the stem cell niche as a prerequisite to stem cell replenishment.


Assuntos
Arabidopsis/citologia , Arabidopsis/metabolismo , Brassinosteroides/metabolismo , Comunicação Parácrina , Regeneração , Transdução de Sinais , Nicho de Células-Tronco , Proteínas de Arabidopsis/metabolismo , Microambiente Celular , Dano ao DNA , Regulação para Baixo/genética , Regulação da Expressão Gênica de Plantas , Proteínas de Membrana/metabolismo , Meristema/citologia , Meristema/metabolismo , Modelos Biológicos , Raízes de Plantas/citologia , Raízes de Plantas/metabolismo , Plantas Geneticamente Modificadas , Plântula/citologia , Plântula/metabolismo , Transcrição Genética
7.
Development ; 144(9): 1619-1628, 2017 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-28320734

RESUMO

The transcription factor BRI1-EMS-SUPRESSOR 1 (BES1) is a master regulator of brassinosteroid (BR)-regulated gene expression. BES1 together with BRASSINAZOLE-RESISTANT 1 (BZR1) drive activated or repressed expression of several genes, and have a prominent role in negative regulation of BR synthesis. Here, we report that BES1 interaction with TOPLESS (TPL), via its ERF-associated amphiphilic repression (EAR) motif, is essential for BES1-mediated control of organ boundary formation in the shoot apical meristem and the regulation of quiescent center (QC) cell division in roots. We show that TPL binds via BES1 to the promoters of the CUC3 and BRAVO targets and suppresses their expression. Ectopic expression of TPL leads to similar organ boundary defects and alterations in QC cell division rate to the bes1-d mutation, while bes1-d defects are suppressed by the dominant interfering protein encoded by tpl-1, with these effects respectively correlating with changes in CUC3 and BRAVO expression. Together, our data unveil a pivotal role of the co-repressor TPL in the shoot and root meristems, which relies on its interaction with BES1 and regulation of BES1 target gene expression.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/embriologia , Arabidopsis/metabolismo , Brassinosteroides/metabolismo , Meristema/embriologia , Meristema/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Divisão Celular , Flores/fisiologia , Dosagem de Genes , Regulação da Expressão Gênica de Plantas , Organogênese , Fenótipo , Folhas de Planta/embriologia , Regiões Promotoras Genéticas/genética , Ligação Proteica , Transcrição Genética
8.
Methods Mol Biol ; 1544: 3-19, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28050824

RESUMO

The plant vascular system provides transport and mechanical support functions that are essential for suitable plant growth and development. In Arabidopsis thaliana (Arabidopsis), the vascular tissues at the shoot inflorescence stems are disposed in organized vascular bundles. The vascular patterning emergence and development within the shoot inflorescence stems is under the control of plant growth regulators (De Rybel et al., Nat Rev Mol Cell Biol 17:30-40, 2016; Caño-Delgado et al., Annu Rev Cell Dev Biol 26:605-637, 2010). By using a combined approach of experimental methods for vascular tissues visualization and quantification together with theoretical methods through mathematical and computational modeling, we have reported that auxin transport and brassinosteroid signaling play complementary roles in the formation of the periodic vascular patterning in the shoot (Ibañes et al., Proc Natl Acad Sci U S A 106:13630-13635, 2009; Fàbregas et al., Plant Signal Behav 5:903-906, 2010; Fàbregas et al., PLoS Genet 11:e1005183, 2015). Here, we report the methodology for the interdisciplinary analysis of the shoot vascular patterning in the plant model Arabidopsis into a handle procedure for visualization, quantification, data analysis, and modeling implementation.


Assuntos
Modelos Biológicos , Brotos de Planta/citologia , Brotos de Planta/crescimento & desenvolvimento , Feixe Vascular de Plantas/citologia , Feixe Vascular de Plantas/crescimento & desenvolvimento , Algoritmos , Imuno-Histoquímica , Desenvolvimento Vegetal
9.
Methods Mol Biol ; 1564: 103-120, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28124249

RESUMO

Mathematical modeling of biological processes is a useful tool to draw conclusions that are contained in the data, but not directly reachable, as well as to make predictions and select the most efficient follow-up experiments. Here we outline a method to model systems of a few proteins that interact transcriptionally and/or posttranscriptionally, by representing the system as Ordinary Differential Equations and to study the model dynamics and stationary states. We exemplify this method by focusing on the regulation by the brassinosteroid (BR) signaling component BRASSINOSTEROID INSENSITIVE1 ETHYL METHYL SULFONATE SUPPRESSOR1 (BES1) of BRAVO, a quiescence-regulating transcription factor expressed in the quiescent cells of Arabidopsis thaliana roots. The method to extract the stationary states and the dynamics is provided as a Mathematica code and requires basic knowledge of the Mathematica software to be executed.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/efeitos dos fármacos , Brassinosteroides/farmacologia , Regulação da Expressão Gênica de Plantas , Proteínas Nucleares/genética , Reguladores de Crescimento de Planta/farmacologia , Esteroides Heterocíclicos/farmacologia , Fatores de Transcrição/genética , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas de Ligação a DNA , Regulação da Expressão Gênica no Desenvolvimento , Computação Matemática , Modelos Biológicos , Proteínas Nucleares/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Biossíntese de Proteínas , Transdução de Sinais , Fatores de Transcrição/metabolismo , Transcrição Genética
10.
Methods Mol Biol ; 1564: 181-192, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28124255

RESUMO

Roots anchor plants to the soil and are essential for a successful plant growth and adaptation to the environment. Research on the primary root in the plant model system Arabidopsis thaliana has yielded important advances in the molecular and cellular understanding of root growth and development. Several studies have uncovered how the hormones brassinosteroids (BRs) control cell cycle and differentiation programs through different cell-specific signaling pathways that are key for root growth and development. Currently, an important challenge resides in the translation of the current knowledge on Arabidopsis roots into agronomically valuable species to improve the agricultural production and to meet the food security goals of the millennium. In this chapter, we characterize the primary root apex of the cereal Sorghum bicolor (L. Moench) (sorghum), analyze the physiological response of sorghum roots to BRs, and examine the phylogeny of the BRASSINOSTEROID INSENSITIVE1-like receptor family in Arabidopsis and its orthologous genes in sorghum. Overall, we support the use of sorghum as a suitable crop model species for the study of BR signaling in root growth and development. The methods presented enable any laboratory worldwide to use sorghum primary roots as a favorite organ for the study of growth and development in crops.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/efeitos dos fármacos , Brassinosteroides/farmacologia , Regulação da Expressão Gênica de Plantas , Raízes de Plantas/efeitos dos fármacos , Proteínas Quinases/genética , Transdução de Sinais , Sorghum/efeitos dos fármacos , Esteroides Heterocíclicos/farmacologia , Arabidopsis/classificação , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/metabolismo , Sequência Conservada , Regulação da Expressão Gênica no Desenvolvimento , Microscopia Confocal , Microtomia/instrumentação , Microtomia/métodos , Filogenia , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Propídio , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Proteínas Quinases/metabolismo , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Plântula/efeitos dos fármacos , Plântula/genética , Plântula/crescimento & desenvolvimento , Plântula/metabolismo , Sorghum/classificação , Sorghum/genética , Sorghum/crescimento & desenvolvimento , Inclusão do Tecido/métodos
11.
J Exp Bot ; 67(17): 4951-61, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27511026

RESUMO

Brassinosteroid (BR) hormones are important regulators of plant growth and development. Recent studies revealed the cell-specific role of BRs in vascular and stem cell development by the action of cell-specific BR receptor complexes and downstream signaling components in Arabidopsis thaliana Despite the importance of spatiotemporal regulation of hormone signaling in the control of plant vascular development, the mechanisms that confer cellular specificity to BR receptors within the vascular cells are not yet understood. The present work shows that BRI1-like receptor genes 1 and 3 (BRL1 and BRL3) are differently regulated by BRs. By using promoter deletion constructs of BRL1 and BRL3 fused to GFP/GUS (green fluorescent protein/ß-glucuronidase) reporters in Arabidopsis, analysis of their cell-specific expression and regulation by BRs in the root apex has been carried out. We found that BRL3 expression is finely modulated by BRs in different root cell types, whereas the location of BRL1 appears to be independent of this hormone. Physiological and genetic analysis show a BR-dependent expression of BRL3 in the root meristem. In particular, BRL3 expression requires active BES1, a central transcriptional effector within the BRI1 pathway. ChIP analysis showed that BES1 directly binds to the BRRE present in the BRL3 promoter region, modulating its transcription in different subsets of cells of the root apex. Overall our study reveals the existence of a cell-specific negative feedback loop from BRI1-mediated BES1 transcription factor to BRL3 in phloem cells, while contributing to a general understanding of the spatial control of steroid signaling in plant development.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/metabolismo , Proteínas Nucleares/fisiologia , Raízes de Plantas/metabolismo , Receptores de Superfície Celular/metabolismo , Arabidopsis/fisiologia , Brassinosteroides/metabolismo , Proteínas de Ligação a DNA , Reguladores de Crescimento de Planta/metabolismo , Raízes de Plantas/fisiologia , Receptores de Superfície Celular/fisiologia
12.
Cell Rep ; 11(6): 977-989, 2015 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-25937286

RESUMO

Telomeres are specialized nucleoprotein caps that protect chromosome ends assuring cell division. Single-cell telomere quantification in animals established a critical role for telomerase in stem cells, yet, in plants, telomere-length quantification has been reported only at the organ level. Here, a quantitative analysis of telomere length of single cells in Arabidopsis root apex uncovered a heterogeneous telomere-length distribution of different cell lineages showing the longest telomeres at the stem cells. The defects in meristem and stem cell renewal observed in tert mutants demonstrate that telomere lengthening by TERT sets a replicative limit in the root meristem. Conversely, the long telomeres of the columella cells and the premature stem cell differentiation plt1,2 mutants suggest that differentiation can prevent telomere erosion. Overall, our results indicate that telomere dynamics are coupled to meristem activity and continuous growth, disclosing a critical association between telomere length, stem cell function, and the extended lifespan of plants.


Assuntos
Arabidopsis/citologia , Arabidopsis/metabolismo , Meristema/citologia , Análise de Célula Única/métodos , Células-Tronco/citologia , Telômero/metabolismo , Proteínas de Arabidopsis/metabolismo , Compartimento Celular , Diferenciação Celular , Divisão Celular , Hibridização in Situ Fluorescente , Meristema/metabolismo , Mutação/genética , Nicho de Células-Tronco , Células-Tronco/metabolismo , Telomerase/metabolismo
13.
PLoS Genet ; 11(4): e1005183, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25922946

RESUMO

Auxin is an essential hormone for plant growth and development. Auxin influx carriers AUX1/LAX transport auxin into the cell, while auxin efflux carriers PIN pump it out of the cell. It is well established that efflux carriers play an important role in the shoot vascular patterning, yet the contribution of influx carriers to the shoot vasculature remains unknown. Here, we combined theoretical and experimental approaches to decipher the role of auxin influx carriers in the patterning and differentiation of vascular tissues in the Arabidopsis inflorescence stem. Our theoretical analysis predicts that influx carriers facilitate periodic patterning and modulate the periodicity of auxin maxima. In agreement, we observed fewer and more spaced vascular bundles in quadruple mutants plants of the auxin influx carriers aux1lax1lax2lax3. Furthermore, we show AUX1/LAX carriers promote xylem differentiation in both the shoot and the root tissues. Influx carriers increase cytoplasmic auxin signaling, and thereby differentiation. In addition to this cytoplasmic role of auxin, our computational simulations propose a role for extracellular auxin as an inhibitor of xylem differentiation. Altogether, our study shows that auxin influx carriers AUX1/LAX regulate vascular patterning and differentiation in plants.


Assuntos
Proteínas de Arabidopsis/genética , Proteínas de Membrana Transportadoras/genética , Xilema/genética , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/metabolismo , Diferenciação Celular/genética , Regulação da Expressão Gênica de Plantas , Ácidos Indolacéticos , Proteínas de Membrana Transportadoras/metabolismo , Desenvolvimento Vegetal/genética , Brotos de Planta/genética , Brotos de Planta/crescimento & desenvolvimento , Xilema/crescimento & desenvolvimento
14.
Dev Cell ; 30(1): 36-47, 2014 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-24981610

RESUMO

The quiescent center (QC) maintains the activity of the surrounding stem cells within the root stem cell niche, yet specific molecular players sustaining the low rate of QC cell division remain poorly understood. Here, we identified a R2R3-MYB transcription factor, BRAVO (BRASSINOSTEROIDS AT VASCULAR AND ORGANIZING CENTER), acting as a cell-specific repressor of QC divisions in the primary root of Arabidopsis. Ectopic BRAVO expression restricts overall root growth and ceases root regeneration upon damage of the stem cells, demonstrating the role of BRAVO in counteracting Brassinosteroid (BR)-mediated cell division in the QC cells. Interestingly, BR-regulated transcription factor BES1 (BRI1-EMS SUPRESSOR 1) directly represses and physically interacts with BRAVO in vivo, creating a switch that modulates QC divisions at the root stem cell niche. Together, our results define a mechanism for BR-mediated regulation of stem cell quiescence in plants.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/crescimento & desenvolvimento , Brassinosteroides/farmacologia , Transdução de Sinais/efeitos dos fármacos , Nicho de Células-Tronco/efeitos dos fármacos , Células-Tronco/citologia , Arabidopsis/efeitos dos fármacos , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Biomarcadores/metabolismo , Western Blotting , Divisão Celular , Proliferação de Células , Imunoprecipitação da Cromatina , Ensaio de Imunoadsorção Enzimática , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Imunoprecipitação , Modelos Teóricos , Mutação/genética , Análise de Sequência com Séries de Oligonucleotídeos , Reguladores de Crescimento de Planta/farmacologia , Raízes de Plantas/citologia , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Plantas Geneticamente Modificadas/efeitos dos fármacos , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/metabolismo , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Células-Tronco/efeitos dos fármacos , Células-Tronco/metabolismo
15.
Physiol Plant ; 151(2): 172-83, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24547704

RESUMO

Brassinosteroid (BR) hormones are essential for plant growth and development. In Arabidopsis, the general understanding of BR signaling has been greatly attained by genetic and biochemical approaches that led to the identification of central BR signaling components, from the BRI1 receptor at the plasma membrane to downstream acting BR-regulated BRZ1 and BES1 transcription factors in the nuclei. Recently, an emerging trend is being established to further advance our understanding of the BR signaling pathway in plant development. Scientists have turned on the microscope lens turret to revisit the pleiotropic phenotypes of the BR mutants at a higher magnification, uncovering novel and specific cellular defects in the plant. In-depth phenotypic analysis in combination with the search for cell-specific signaling components that are responsible for those particular defects in the mutants are leading to: (1) definition of novel roles for BRs in vascular development, (2) unraveling BR function in cell division through quantitative analysis of Arabidopsis root growth, (3) establishment of a molecular connection between known patterning and BR-signaling components in organ boundary and stomata development and (4) development of novel strategies toward the identification of BR signaling components with spatiotemporal resolution. In this review, we highlight the importance of these emerging studies to investigate the spatiotemporal control of BR pathways in plant development.


Assuntos
Arabidopsis/fisiologia , Brassinosteroides/metabolismo , Regulação da Expressão Gênica de Plantas , Reguladores de Crescimento de Planta/metabolismo , Transdução de Sinais , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Mutação , Especificidade de Órgãos , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/fisiologia , Brotos de Planta/genética , Brotos de Planta/crescimento & desenvolvimento , Brotos de Planta/fisiologia , Feixe Vascular de Plantas/genética , Feixe Vascular de Plantas/crescimento & desenvolvimento , Feixe Vascular de Plantas/fisiologia
16.
Plant Physiol ; 164(3): 1527-41, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24492333

RESUMO

Protein phosphatases with Kelch-like domains (PPKL) are members of the phosphoprotein phosphatases family present only in plants and alveolates. PPKL have been described as positive effectors of brassinosteroid (BR) signaling in plants. Most of the evidence supporting this role has been gathered using one of the four homologs in Arabidopsis (Arabidopsis thaliana), brassinosteroid-insensitive1 suppressor (BSU1). We reappraised the roles of the other three members of the family, BSL1, BSL2, and BSL3, through phylogenetic, functional, and genetic analyses. We show that BSL1 and BSL2/BSL3 belong to two ancient evolutionary clades that have been highly conserved in land plants. In contrast, BSU1-type genes are exclusively found in the Brassicaceae and display a remarkable sequence divergence, even among closely related species. Simultaneous loss of function of the close paralogs BSL2 and BSL3 brings about a peculiar array of phenotypic alterations, but with marginal effects on BR signaling; loss of function of BSL1 is, in turn, phenotypically silent. Still, the products of these three genes account for the bulk of PPKL-related activity in Arabidopsis and together have an essential role in the early stages of development that BSU1 is unable to supplement. Our results underline the functional relevance of BSL phosphatases in plants and suggest that BSL2/BSL3 and BSU1 may have contrasting effects on BR signaling. Given that BSU1-type genes have likely undergone a functional shift and are phylogenetically restricted, we caution that inferences based on these genes to the whole family or to other species may be misleading.


Assuntos
Evolução Molecular , Fosfoproteínas Fosfatases/química , Fosfoproteínas Fosfatases/genética , Plantas/enzimologia , Plantas/genética , Arabidopsis/efeitos dos fármacos , Arabidopsis/enzimologia , Arabidopsis/genética , Brassinosteroides/farmacologia , Flores/anatomia & histologia , Flores/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes de Plantas/genética , Mutação/genética , Fenótipo , Filogenia , Proteínas de Plantas/metabolismo , Plantas/efeitos dos fármacos , Estrutura Terciária de Proteína , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Frações Subcelulares/efeitos dos fármacos , Frações Subcelulares/enzimologia
17.
Plant Cell ; 25(9): 3377-88, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24064770

RESUMO

Brassinosteroid (BR) hormones are primarily perceived at the cell surface by the leucine-rich repeat receptor-like kinase brassinosteroid insensitive1 (BRI1). In Arabidopsis thaliana, BRI1 has two close homologs, BRI1-LIKE1 (BRL1) and BRL3, respectively, which are expressed in the vascular tissues and regulate shoot vascular development. Here, we identify novel components of the BRL3 receptor complex in planta by immunoprecipitation and mass spectrometry analysis. Whereas BRI1 associated kinase1 (BAK1) and several other known BRI1 interactors coimmunoprecipitated with BRL3, no evidence was found of a direct interaction between BRI1 and BRL3. In addition, we confirmed that BAK1 interacts with the BRL1 receptor by coimmunoprecipitation and fluorescence microscopy analysis. Importantly, genetic analysis of brl1 brl3 bak1-3 triple mutants revealed that BAK1, BRL1, and BRL3 signaling modulate root growth and development by contributing to the cellular activities of provascular and quiescent center cells. This provides functional relevance to the observed protein-protein interactions of the BRL3 signalosome. Overall, our study demonstrates that cell-specific BR receptor complexes can be assembled to perform different cellular activities during plant root growth, while highlighting that immunoprecipitation of leucine-rich repeat receptor kinases in plants is a powerful approach for unveiling signaling mechanisms with cellular resolution in plant development.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Proteínas Serina-Treonina Quinases/genética , Receptores de Superfície Celular/genética , Transdução de Sinais , Arabidopsis/citologia , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Brassinosteroides/metabolismo , Ciclo Celular , Cromatografia Líquida , Genes Reporter , Complexos Multiproteicos , Mutação , Fenótipo , Floema/citologia , Floema/genética , Floema/crescimento & desenvolvimento , Floema/metabolismo , Raízes de Plantas/citologia , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Plantas Geneticamente Modificadas , Mapeamento de Interação de Proteínas , Proteínas Serina-Treonina Quinases/metabolismo , Receptores de Superfície Celular/metabolismo , Proteínas Recombinantes de Fusão , Espectrometria de Massas em Tandem
18.
Trends Plant Sci ; 18(5): 235-6, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23384602

RESUMO

Two recent studies disclose the interaction between brassinosteroids (BRs) and cell-identity genes in establishing organ boundaries. BR signaling is downregulated by LATERAL ORGAN BOUNDARIES (LOB), whereas active BR signaling prevents LATERAL ORGAN FUSION1 (LOF1) and CUP SHAPED COTYLEDON (CUC) expression in the growing primordia, pointing to cell-specific hormone signaling as part of the mechanisms controlling fate acquisition.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/genética , Brassinosteroides/metabolismo , Regulação da Expressão Gênica de Plantas , Meristema/fisiologia
19.
New Phytol ; 197(2): 490-502, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23253334

RESUMO

Brassinosteroid (BR) hormones control plant growth through acting on both cell expansion and division. Here, we examined the role of BRs in leaf growth using the Arabidopsis BR-deficient mutant constitutive photomorphogenesis and dwarfism (cpd). We show that the reduced size of cpd leaf blades is a result of a decrease in cell size and number, as well as in venation length and complexity. Kinematic growth analysis and tissue-specific marker gene expression revealed that the leaf phenotype of cpd is associated with a prolonged cell division phase and delayed differentiation. cpd-leaf-rescue experiments and leaf growth analysis of BR biosynthesis and signaling gain-of-function mutants showed that BR production and BR receptor-dependent signaling differentially control the balance between cell division and expansion in the leaf. Investigation of cell cycle markers in leaves of cpd revealed the accumulation of mitotic proteins independent of transcription. This correlated with an increase in cyclin-dependent kinase activity, suggesting a role for BRs in control of mitosis.


Assuntos
Arabidopsis/citologia , Arabidopsis/crescimento & desenvolvimento , Brassinosteroides/biossíntese , Divisão Celular , Folhas de Planta/citologia , Folhas de Planta/crescimento & desenvolvimento , Transdução de Sinais , Arabidopsis/efeitos dos fármacos , Proteínas de Arabidopsis/metabolismo , Brassinosteroides/metabolismo , Brassinosteroides/farmacologia , Contagem de Células , Diferenciação Celular/efeitos dos fármacos , Divisão Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Tamanho Celular/efeitos dos fármacos , Mitose/efeitos dos fármacos , Mutação/genética , Fenótipo , Folhas de Planta/efeitos dos fármacos , Proteínas Quinases/metabolismo , Transdução de Sinais/efeitos dos fármacos
20.
Plant Cell ; 24(6): 2262-78, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22693282

RESUMO

Global climate change and a growing population require tackling the reduction in arable land and improving biomass production and seed yield per area under varying conditions. One of these conditions is suboptimal water availability. Here, we review some of the classical approaches to dealing with plant response to drought stress and we evaluate how research on RECEPTOR-LIKE KINASES (RLKs) can contribute to improving plant performance under drought stress. RLKs are considered as key regulators of plant architecture and growth behavior, but they also function in defense and stress responses. The available literature and analyses of available transcript profiling data indeed suggest that RLKs can play an important role in optimizing plant responses to drought stress. In addition, RLK pathways are ideal targets for nontransgenic approaches, such as synthetic molecules, providing a novel strategy to manipulate their activity and supporting translational studies from model species, such as Arabidopsis thaliana, to economically useful crops.


Assuntos
Secas , Fenômenos Fisiológicos Vegetais , Proteínas Quinases/fisiologia , Projetos de Pesquisa , Arabidopsis/fisiologia , Regulação da Expressão Gênica de Plantas , Reguladores de Crescimento de Planta/química , Reguladores de Crescimento de Planta/metabolismo , Biossíntese de Proteínas , Estresse Fisiológico
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