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1.
Proc Natl Acad Sci U S A ; 119(1)2022 01 04.
Artigo em Inglês | MEDLINE | ID: mdl-34949719

RESUMO

Plant cells can be distinguished from animal cells by their cell walls and high-turgor pressure. Although changes in turgor and the stiffness of cell walls seem coordinated, we know little about the mechanism responsible for coordination. Evidence has accumulated that plants, like yeast, have a dedicated cell wall integrity maintenance mechanism. It monitors the functional integrity of the wall and maintains integrity through adaptive responses induced by cell wall damage arising during growth, development, and interactions with the environment. These adaptive responses include osmosensitive induction of phytohormone production, defense responses, as well as changes in cell wall composition and structure. Here, we investigate how the cell wall integrity maintenance mechanism coordinates changes in cell wall stiffness and turgor in Arabidopsis thaliana We show that the production of abscisic acid (ABA), the phytohormone-modulating turgor pressure, and responses to drought depend on the presence of a functional cell wall. We find that the cell wall integrity sensor THESEUS1 modulates mechanical properties of walls, turgor loss point, ABA biosynthesis, and ABA-controlled processes. We identify RECEPTOR-LIKE PROTEIN 12 as a component of cell wall integrity maintenance-controlling, cell wall damage-induced jasmonic acid (JA) production. We propose that THE1 is responsible for coordinating changes in turgor pressure and cell wall stiffness.


Assuntos
Ácido Abscísico/metabolismo , Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Parede Celular/metabolismo , Homeostase , Raízes de Plantas/metabolismo , Plântula/metabolismo
2.
Plant Cell ; 32(4): 1063-1080, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32034035

RESUMO

Reactive oxygen species (ROS) are important messengers in eukaryotic organisms, and their production is tightly controlled. Active extracellular ROS production by NADPH oxidases in plants is triggered by receptor-like protein kinase-dependent signaling networks. Here, we show that CYSTEINE-RICH RLK2 (CRK2) kinase activity is required for plant growth and CRK2 exists in a preformed complex with the NADPH oxidase RESPIRATORY BURST OXIDASE HOMOLOG D (RBOHD) in Arabidopsis (Arabidopsis thaliana). Functional CRK2 is required for the full elicitor-induced ROS burst, and consequently the crk2 mutant is impaired in defense against the bacterial pathogen Pseudomonas syringae pv tomato DC3000. Our work demonstrates that CRK2 regulates plant innate immunity. We identified in vitro CRK2-dependent phosphorylation sites in the C-terminal region of RBOHD. Phosphorylation of S703 RBOHD is enhanced upon flg22 treatment, and substitution of S703 with Ala reduced ROS production in Arabidopsis. Phylogenetic analysis suggests that phospho-sites in the C-terminal region of RBOHD are conserved throughout the plant lineage and between animals and plants. We propose that regulation of NADPH oxidase activity by phosphorylation of the C-terminal region might be an ancient mechanism and that CRK2 is an important element in regulating microbe-associated molecular pattern-triggered ROS production.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , NADPH Oxidases/química , NADPH Oxidases/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Animais , Arabidopsis/efeitos dos fármacos , Arabidopsis/microbiologia , Proteínas de Arabidopsis/química , Sequência Conservada , Citosol/efeitos dos fármacos , Citosol/metabolismo , Resistência à Doença , Flagelina/farmacologia , Células HEK293 , Humanos , Modelos Biológicos , Moléculas com Motivos Associados a Patógenos/metabolismo , Fosforilação/efeitos dos fármacos , Fosfosserina/metabolismo , Desenvolvimento Vegetal/efeitos dos fármacos , Doenças das Plantas/microbiologia , Ligação Proteica/efeitos dos fármacos , Proteínas Serina-Treonina Quinases/química , Pseudomonas syringae/patogenicidade , Pseudomonas syringae/fisiologia , Virulência/efeitos dos fármacos
3.
Plant Mol Biol ; 109(4-5): 483-504, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35674976

RESUMO

Plant cell walls are highly dynamic and chemically complex structures surrounding all plant cells. They provide structural support, protection from both abiotic and biotic stress as well as ensure containment of turgor. Recently evidence has accumulated that a dedicated mechanism exists in plants, which is monitoring the functional integrity of cell walls and initiates adaptive responses to maintain integrity in case it is impaired during growth, development or exposure to biotic and abiotic stress. The available evidence indicates that detection of impairment involves mechano-perception, while reactive oxygen species and phytohormone-based signaling processes play key roles in translating signals generated and regulating adaptive responses. More recently it has also become obvious that the mechanisms mediating cell wall integrity maintenance and pattern triggered immunity are interacting with each other to modulate the adaptive responses to biotic stress and cell wall integrity impairment. Here we will review initially our current knowledge regarding the mode of action of the maintenance mechanism, discuss mechanisms mediating responses to biotic stresses and highlight how both mechanisms may modulate adaptive responses. This first part will be focused on Arabidopsis thaliana since most of the relevant knowledge derives from this model organism. We will then proceed to provide perspective to what extent the relevant molecular mechanisms are conserved in other plant species and close by discussing current knowledge of the transcriptional machinery responsible for controlling the adaptive responses using selected examples.


Assuntos
Arabidopsis , Transdução de Sinais , Arabidopsis/genética , Parede Celular/fisiologia , Regulação da Expressão Gênica de Plantas , Células Vegetais/fisiologia , Plantas , Estresse Fisiológico
4.
Development ; 145(19)2018 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-30190280

RESUMO

During plant growth and defense, cell cycle activity needs to be coordinated with cell wall integrity. Little is known about how this coordination is achieved. Here, we investigated coordination in Arabidopsis thaliana seedlings by studying the impact of cell wall damage (CWD, caused by cellulose biosynthesis inhibition) on cytokinin homeostasis, cell cycle gene expression and cell shape in root tips. CWD inhibited cell cycle gene expression and increased transition zone cell width in an osmosensitive manner. These results were correlated with CWD-induced, osmosensitive changes in cytokinin homeostasis. Expression of CYTOKININ OXIDASE/DEHYDROGENASE 2 and 3 (CKX2, CKX3), which encode cytokinin-degrading enzymes, was induced by CWD and reduced by osmoticum treatment. In nitrate reductase1 nitrate reductase2 (nia1 nia2) seedlings, CKX2 and CKX3 transcript levels were not increased and cell cycle gene expression was not repressed by CWD. Moreover, established CWD-induced responses, such as jasmonic acid, salicylic acid and lignin production, were also absent, implying a central role of NIA1/2-mediated processes in regulation of CWD responses. These results suggest that CWD enhances cytokinin degradation rates through a NIA1/2-mediated process, leading to attenuation of cell cycle gene expression.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/citologia , Arabidopsis/genética , Ciclo Celular/genética , Parede Celular/metabolismo , Regulação da Expressão Gênica de Plantas , Nitrato Redutase/metabolismo , Arabidopsis/efeitos dos fármacos , Benzamidas/farmacologia , Ciclo Celular/efeitos dos fármacos , Parede Celular/efeitos dos fármacos , Citocininas/farmacologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Homeostase/efeitos dos fármacos , Modelos Biológicos , Osmose , Fenótipo , Raízes de Plantas/citologia , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Plântula/efeitos dos fármacos , Plântula/genética , Sorbitol/farmacologia
5.
Cell Mol Life Sci ; 77(11): 2049-2077, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31781810

RESUMO

The walls surrounding the cells of all land-based plants provide mechanical support essential for growth and development as well as protection from adverse environmental conditions like biotic and abiotic stress. Composition and structure of plant cell walls can differ markedly between cell types, developmental stages and species. This implies that wall composition and structure are actively modified during biological processes and in response to specific functional requirements. Despite extensive research in the area, our understanding of the regulatory processes controlling active and adaptive modifications of cell wall composition and structure is still limited. One of these regulatory processes is the cell wall integrity maintenance mechanism, which monitors and maintains the functional integrity of the plant cell wall during development and interaction with environment. It is an important element in plant pathogen interaction and cell wall plasticity, which seems at least partially responsible for the limited success that targeted manipulation of cell wall metabolism has achieved so far. Here, we provide an overview of the cell wall polysaccharides forming the bulk of plant cell walls in both monocotyledonous and dicotyledonous plants and the effects their impairment can have. We summarize our current knowledge regarding the cell wall integrity maintenance mechanism and discuss that it could be responsible for several of the mutant phenotypes observed.


Assuntos
Parede Celular/metabolismo , Produtos Agrícolas/metabolismo , Células Vegetais/metabolismo , Plantas/metabolismo , Polissacarídeos/metabolismo , Vias Biossintéticas , Parede Celular/química , Produtos Agrícolas/química , Células Vegetais/química , Plantas/química , Polissacarídeos/análise
6.
PLoS Genet ; 13(6): e1006832, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28604776

RESUMO

Plants actively perceive and respond to perturbations in their cell walls which arise during growth, biotic and abiotic stresses. However, few components involved in plant cell wall integrity sensing have been described to date. Using a reverse-genetic approach, we identified the Arabidopsis thaliana leucine-rich repeat receptor kinase MIK2 as an important regulator of cell wall damage responses triggered upon cellulose biosynthesis inhibition. Indeed, loss-of-function mik2 alleles are strongly affected in immune marker gene expression, jasmonic acid production and lignin deposition. MIK2 has both overlapping and distinct functions with THE1, a malectin-like receptor kinase previously proposed as cell wall integrity sensor. In addition, mik2 mutant plants exhibit enhanced leftward root skewing when grown on vertical plates. Notably, natural variation in MIK2 (also named LRR-KISS) has been correlated recently to mild salt stress tolerance, which we could confirm using our insertional alleles. Strikingly, both the increased root skewing and salt stress sensitivity phenotypes observed in the mik2 mutant are dependent on THE1. Finally, we found that MIK2 is required for resistance to the fungal root pathogen Fusarium oxysporum. Together, our data identify MIK2 as a novel component in cell wall integrity sensing and suggest that MIK2 is a nexus linking cell wall integrity sensing to growth and environmental cues.


Assuntos
Proteínas de Arabidopsis/genética , Parede Celular/genética , Raízes de Plantas/genética , Proteínas Quinases/genética , Receptores de Superfície Celular/genética , Estresse Fisiológico/genética , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Proteínas de Arabidopsis/biossíntese , Parede Celular/efeitos dos fármacos , Celulose/biossíntese , Ciclopentanos/metabolismo , Resistência à Doença/genética , Fusarium/patogenicidade , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Lignina/biossíntese , Oxilipinas/metabolismo , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Raízes de Plantas/efeitos dos fármacos , Proteínas Quinases/biossíntese , Cloreto de Sódio/toxicidade , Estresse Fisiológico/efeitos dos fármacos
7.
BMC Plant Biol ; 19(1): 320, 2019 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-31319813

RESUMO

BACKGROUND: Plant cell walls participate in all plant-environment interactions. Maintaining cell wall integrity (CWI) during these interactions is essential. This realization led to increased interest in CWI and resulted in knowledge regarding early perception and signalling mechanisms active during CWI maintenance. By contrast, knowledge regarding processes mediating changes in cell wall metabolism upon CWI impairment is very limited. RESULTS: To identify genes involved and to investigate their contributions to the processes we selected 23 genes with altered expression in response to CWI impairment and characterized the impact of T-DNA insertions in these genes on cell wall composition using Fourier-Transform Infrared Spectroscopy (FTIR) in Arabidopsis thaliana seedlings. Insertions in 14 genes led to cell wall phenotypes detectable by FTIR. A detailed analysis of four genes found that their altered expression upon CWI impairment is dependent on THE1 activity, a key component of CWI maintenance. Phenotypic characterizations of insertion lines suggest that the four genes are required for particular aspects of CWI maintenance, cell wall composition or resistance to Plectosphaerella cucumerina infection in adult plants. CONCLUSION: Taken together, the results implicate the genes in responses to CWI impairment, cell wall metabolism and/or pathogen defence, thus identifying new molecular components and processes relevant for CWI maintenance.


Assuntos
Arabidopsis/genética , Parede Celular/metabolismo , Genes de Plantas/fisiologia , Arabidopsis/metabolismo , Arabidopsis/fisiologia , Ascomicetos , Parede Celular/fisiologia , Resistência à Doença/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas/genética , Técnicas de Silenciamento de Genes , Interações Hospedeiro-Patógeno , Doenças das Plantas/imunologia , Plântula/metabolismo , Plântula/fisiologia , Espectroscopia de Infravermelho com Transformada de Fourier
8.
BMC Plant Biol ; 19(1): 385, 2019 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-31488059

RESUMO

Following publication of the original article [1], the author reported that the two curves in the sub-diagram WSR4 in Fig. 2a should be the other way round.

9.
Physiol Plant ; 164(1): 82-94, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29652097

RESUMO

During recent years it has become accepted that plant cell walls are not inert objects surrounding all plant cells but are instead highly dynamic, plastic structures. They are involved in a large number of cell biological processes and contribute actively to plant growth, development and interaction with environment. Therefore, it is not surprising that cellular processes can control plant cell wall integrity (CWI) while, simultaneously, CWI can influence cellular processes. In yeast and animal cells such a bidirectional relationship also exists between the yeast/animal extracellular matrices and the cell cycle. In yeast, the CWI maintenance mechanism and a dedicated plasma membrane integrity checkpoint are mediating this relationship. Recent research has yielded insights into the mechanism controlling plant cell wall metabolism during cytokinesis. However, the knowledge regarding putative regulatory pathways controlling adaptive modifications in plant cell cycle activity in response to changes in the state of the plant cell wall are not yet identified. In this review, we summarize similarities and differences in regulatory mechanisms coordinating extracellular matrices and cell cycle activity in animal and yeast cells, discuss the available evidence supporting the existence of such a mechanism in plants and suggest that the plant CWI maintenance mechanism might also control cell cycle activity in plant cells.


Assuntos
Ciclo Celular/fisiologia , Parede Celular/metabolismo , Plantas/metabolismo , Parede Celular/fisiologia , Transdução de Sinais/fisiologia
10.
J Exp Bot ; 68(13): 3287-3301, 2017 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-28472349

RESUMO

Dirigent (DIR) proteins were found to mediate regio- and stereoselectivity of bimolecular phenoxy radical coupling during lignan biosynthesis. Here we summarize the current knowledge of the importance of DIR proteins in lignan and lignin biosynthesis and highlight their possible importance in plant development. We focus on the still rather enigmatic Arabidopsis DIR gene family, discussing the few members with known functional importance. We comment on recent discoveries describing the detailed structure of two DIR proteins with implications in the mechanism of DIR-mediated catalysis. Further, we summarize the ample evidence for stress-induced dirigent gene expression, suggesting the role of DIRs in adaptive responses. In the second part of our work, we present a preliminary bioinformatics-based characterization of the AtDIR family. The phylogenetic analysis of AtDIRs complemented by comparison with DIR proteins of mostly known function from other species allowed us to suggest possible roles for several members of this family and identify interesting AtDIR targets for further study. Finally, based on the available metadata and our in silico analysis of AtDIR promoters, we hypothesize about the existence of specific transcriptional controls for individual AtDIR genes and implicate them in various stress responses, hormonal regulations, and developmental processes.


Assuntos
Arabidopsis/genética , Proteínas de Plantas/genética , Arabidopsis/química , Arabidopsis/metabolismo , Biologia Computacional , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo
11.
Plant Cell Physiol ; 56(2): 215-23, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25416836

RESUMO

One of the main differences between plant and animal cells are the walls surrounding plant cells providing structural support during development and protection like an adaptive armor against biotic and abiotic stress. During recent years it has become widely accepted that plant cells use a dedicated system to monitor and maintain the functional integrity of their walls. Maintenance of integrity is achieved by modifying the cell wall and cellular metabolism in order to permit tightly controlled changes in wall composition and structure. While a substantial amount of evidence supporting the existence of the mechanism has been reported, knowledge regarding its precise mode of action is still limited. The currently available evidence suggests similarities of the plant mechanism with respect to both design principles and molecular components involved to the very well characterized system active in the model organism Saccharomyces cerevisiae. There the system has been implicated in cell morphogenesis as well as response to abiotic stresses such as osmotic challenges. Here the currently available knowledge on the yeast system will be reviewed initially to provide a framework for the subsequent discussion of the plant cell wall integrity maintenance mechanism. The review will then end with a discussion on possible design principles for the cell wall integrity maintenance mechanism and the function of the plant turgor pressure in this context.


Assuntos
Parede Celular/metabolismo , Células Vegetais/metabolismo , Modelos Biológicos , Saccharomyces cerevisiae/citologia , Transdução de Sinais
12.
Ann Bot ; 114(6): 1339-47, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24723447

RESUMO

BACKGROUND: Plant cell walls form the interface between the cells and their environment. They perform different functions, such as protecting cells from biotic and abiotic stress and providing structural support during development. Maintenance of the functional integrity of cell walls during these different processes is a prerequisite that enables the walls to perform their particular functions. The available evidence suggests that an integrity maintenance mechanism exists in plants that is capable of both detecting wall integrity impairment caused by cell wall damage and initiating compensatory responses to maintain functional integrity. The responses involve 1-aminocyclopropane-1-carboxylic acid (ACC), jasmonic acid, reactive oxygen species and calcium-based signal transduction cascades as well as the production of lignin and other cell wall components. Experimental evidence implicates clearly different signalling molecules, but knowledge regarding contributions of receptor-like kinases to this process is less clear. Different receptor-like kinase families have been considered as possible sensors for perception of cell wall damage; however, strong experimental evidence that provides insights into functioning exists for very few kinases. SCOPE AND CONCLUSIONS: This review examines the involvement of cell wall integrity maintenance in different biological processes, defines what constitutes plant cell wall damage that impairs functional integrity, clarifies which stimulus perception and signal transduction mechanisms are required for integrity maintenance and assesses the available evidence regarding the functions of receptor-like kinases during cell wall integrity maintenance. The review concludes by discussing how the plant cell wall integrity maintenance mechanism could form an essential component of biotic stress responses and of plant development, functions that have not been fully recognized to date.


Assuntos
Parede Celular/fisiologia , Células Vegetais/enzimologia , Plantas/enzimologia , Proteínas Quinases/metabolismo , Transdução de Sinais , Aminoácidos Cíclicos/metabolismo , Ciclopentanos/metabolismo , Lignina/metabolismo , Modelos Biológicos , Oxilipinas/metabolismo , Células Vegetais/fisiologia , Reguladores de Crescimento de Plantas/metabolismo , Proteínas de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo
13.
Plant Physiol ; 159(1): 105-17, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22422940

RESUMO

Cellulose is the most abundant biopolymer in the world, the main load-bearing element in plant cell walls, and represents a major sink for carbon fixed during photosynthesis. Previous work has shown that photosynthetic activity is partially regulated by carbohydrate sinks. However, the coordination of cellulose biosynthesis with carbohydrate metabolism and photosynthesis is not well understood. Here, we demonstrate that cellulose biosynthesis inhibition (CBI) leads to reductions in transcript levels of genes involved in photosynthesis, the Calvin cycle, and starch degradation in Arabidopsis (Arabidopsis thaliana) seedlings. In parallel, we show that CBI induces changes in carbohydrate distribution and influences Rubisco activase levels. We find that the effects of CBI on gene expression and carbohydrate metabolism can be neutralized by osmotic support in a concentration-dependent manner. However, osmotic support does not suppress CBI-induced metabolic changes in seedlings impaired in mechanoperception (mid1 complementing activity1 [mca1]) and osmoperception (cytokinin receptor1 [cre1]) or reactive oxygen species production (respiratory burst oxidase homolog DF [rbohDF]). These results show that carbohydrate metabolism is responsive to changes in cellulose biosynthesis activity and turgor pressure. The data suggest that MCA1, CRE1, and RBOHDF-derived reactive oxygen species are involved in the regulation of osmosensitive metabolic changes. The evidence presented here supports the notion that cellulose and carbohydrate metabolism may be coordinated via an osmosensitive mechanism.


Assuntos
Arabidopsis/metabolismo , Metabolismo dos Carboidratos , Celulose/biossíntese , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Benzamidas/farmacologia , Sobrevivência Celular , Celulose/antagonistas & inibidores , Celulose/genética , Ativação Enzimática , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , NADPH Oxidases/genética , NADPH Oxidases/metabolismo , Pressão Osmótica , Fotossíntese , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Polietilenoglicóis/farmacologia , Proteínas Quinases/genética , Proteínas Quinases/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Transdução de Sinais , Fatores de Tempo
15.
Plant Physiol ; 156(3): 1364-74, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21546454

RESUMO

The plant cell wall is a dynamic and complex structure whose functional integrity is constantly being monitored and maintained during development and interactions with the environment. In response to cell wall damage (CWD), putatively compensatory responses, such as lignin production, are initiated. In this context, lignin deposition could reinforce the cell wall to maintain functional integrity. Lignin is important for the plant's response to environmental stress, for reinforcement during secondary cell wall formation, and for long-distance water transport. Here, we identify two stages and several components of a genetic network that regulate CWD-induced lignin production in Arabidopsis (Arabidopsis thaliana). During the early stage, calcium and diphenyleneiodonium-sensitive reactive oxygen species (ROS) production are required to induce a secondary ROS burst and jasmonic acid (JA) accumulation. During the second stage, ROS derived from the NADPH oxidase RESPIRATORY BURST OXIDASE HOMOLOG D and JA-isoleucine generated by JASMONIC ACID RESISTANT1, form a negative feedback loop that can repress each other's production. This feedback loop in turn seems to influence lignin accumulation. Our results characterize a genetic network enabling plants to regulate lignin biosynthesis in response to CWD through dynamic interactions between JA and ROS.


Assuntos
Arabidopsis/citologia , Arabidopsis/metabolismo , Parede Celular/metabolismo , Ciclopentanos/metabolismo , Lignina/biossíntese , Oxilipinas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Acetatos/farmacologia , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Cálcio/metabolismo , Parede Celular/efeitos dos fármacos , Ciclopentanos/farmacologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes de Plantas/genética , Modelos Biológicos , Mutação/genética , Oniocompostos/farmacologia , Oxilipinas/farmacologia , Fenótipo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Plântula/efeitos dos fármacos , Plântula/metabolismo , Transdução de Sinais/efeitos dos fármacos
16.
Plant J ; 57(6): 1015-26, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19036034

RESUMO

Development, abiotic and biotic stress each affect the physical architecture and chemical composition of the plant cell wall, making maintenance of cell-wall integrity an important component of many plant processes. Cellulose biosynthesis inhibition (CBI) was employed to impair the functional integrity of the cell wall, and the plant's response to this specific stress was characterized in an Arabidopsis seedling model system. CBI caused changes in the expression of genes involved in mechanoperception, the response to microbial challenge, and lignin and cell-wall polysaccharide biosynthesis. Following CBI, activation of a UDP-D-xylose 4-epimerase gene correlated with increases in arabinose and uronic acid content in seedling cell walls. Activation of pathogen response genes, lignin deposition and lesion formation were dependent on externally supplied sugars and were suppressed by osmotic support. Lignin deposition in the root elongation zone caused by CBI was reduced in atrbohd (NADPH oxidase) mutant seedlings but increased in jasmonic acid resistant1 (jar1-1) mutant seedlings. Phytohormone measurements showed that CBI-induced increases in jasmonic (JA) and salicylic acids were dependent on sugar availability and prevented by osmotic support. We show that CBI activates responses commonly attributed to both abiotic and microbial challenges. Glucose/sucrose and turgor pressure are critical components in maintenance of cell-wall integrity and the regulation of induced responses, including JA biosynthesis. Lignin deposition induced by CBI is regulated by JAR1-1 and NADPH oxidase-dependent signalling processes. Our results identify components of the mechanism that mediates the response to impairment of cell-wall integrity in Arabidopsis thaliana.


Assuntos
Arabidopsis/metabolismo , Parede Celular/metabolismo , Celulose/biossíntese , Hexoses/metabolismo , Arabidopsis/genética , Ciclopentanos/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Lignina/metabolismo , Osmose , Oxilipinas/metabolismo , RNA de Plantas/metabolismo , Ácido Salicílico/metabolismo , Transdução de Sinais , Estresse Fisiológico
17.
Nature ; 426(6963): 147-53, 2003 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-14614497

RESUMO

Axis formation occurs in plants, as in animals, during early embryogenesis. However, the underlying mechanism is not known. Here we show that the first manifestation of the apical-basal axis in plants, the asymmetric division of the zygote, produces a basal cell that transports and an apical cell that responds to the signalling molecule auxin. This apical-basal auxin activity gradient triggers the specification of apical embryo structures and is actively maintained by a novel component of auxin efflux, PIN7, which is located apically in the basal cell. Later, the developmentally regulated reversal of PIN7 and onset of PIN1 polar localization reorganize the auxin gradient for specification of the basal root pole. An analysis of pin quadruple mutants identifies PIN-dependent transport as an essential part of the mechanism for embryo axis formation. Our results indicate how the establishment of cell polarity, polar auxin efflux and local auxin response result in apical-basal axis formation of the embryo, and thus determine the axiality of the adult plant.


Assuntos
Arabidopsis/embriologia , Arabidopsis/metabolismo , Padronização Corporal , Ácidos Indolacéticos/metabolismo , Proteínas de Membrana Transportadoras , Transdução de Sinais , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Dados de Sequência Molecular , Mutação , Transporte Proteico
18.
Curr Biol ; 30(14): R804-R806, 2020 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-32693072

RESUMO

Turgor manipulation to induce plant cell swelling is one of the classic experiments undertaken in biology courses in schools and at universities. However, only now do we start to understand the molecular mechanisms responsible for detecting plant cell swelling.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Biologia , Canais Iônicos , Proteínas de Membrana , Plântula , Universidades
19.
Plants (Basel) ; 9(5)2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32369932

RESUMO

The plant cell walls surrounding all plant cells are highly dynamic structures, which change their composition and organization in response to chemical and physical stimuli originating both in the environment and in plants themselves. They are intricately involved in all interactions between plants and their environment while also providing adaptive structural support during plant growth and development. A key mechanism contributing to these adaptive changes is the cell wall integrity (CWI) maintenance mechanism. It monitors and maintains the functional integrity of cell walls by initiating adaptive changes in cellular and cell wall metabolism. Despite its importance, both our understanding of its mode of action and knowledge regarding the molecular components that form it are limited. Intriguingly, the available evidence implicates mechanosensing in the mechanism. Here, we provide an overview of the knowledge available regarding the molecular mechanisms involved in and discuss how mechanoperception and signal transduction may contribute to plant CWI maintenance.

20.
Nat Plants ; 5(9): 924-932, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31506641

RESUMO

Cell walls are highly dynamic structures that provide mechanical support for plant cells during growth, development and adaptation to a changing environment. Thus, it is important for plants to monitor the state of their cell walls and ensure their functional integrity at all times. This monitoring involves perception of physical forces at the cell wall-plasma membrane interphase. These forces are altered during cell division and morphogenesis, as well as in response to various abiotic and biotic stresses. Mechanisms responsible for the perception of physical stimuli involved in these processes have been difficult to separate from other regulatory mechanisms perceiving chemical signals such as hormones, peptides or cell wall fragments. However, recently developed technologies in combination with more established genetic and biochemical approaches are beginning to open up this exciting field of study. Here, we will review our current knowledge of plant cell wall integrity signalling using selected recent findings and highlight how the cell wall-plasma membrane interphase can act as a venue for sensing changes in the physical forces affecting plant development and stress responses. More importantly, we discuss how these signals may be integrated with chemical signals derived from established signalling cascades to control specific adaptive responses during exposure to biotic and abiotic stresses.


Assuntos
Parede Celular/metabolismo , Células Vegetais/fisiologia , Desenvolvimento Vegetal , Transdução de Sinais , Estresse Fisiológico
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