Biochemical changes induced by phytoplasmas in plants.

2021 ◽  
Vol 16 (051) ◽  
Author(s):  
Chamran Hemmati
Keyword(s):  
Free Amino ◽  
Defense Mechanisms ◽  
Photosynthetic Activity ◽  
Chemical Compounds ◽  
Effector Proteins ◽  
Yield Losses ◽  
Biochemical Responses ◽  
Phytoplasma Infection ◽  
Sap Feeding ◽  
Composition Changes

Abstract Phytoplasmas are cell wall-less and pleomorphic bacterial pathogens that cause considerable yield losses in more than 1000 plant species worldwide and transmitted by sap-feeding insects. Phytoplasma-infected plants exhibit symptoms including witches' broom, phyllody, virescence, yellowing induced by the phytoplasma effector proteins. It has been revealed that phytoplasmas are capable of modulating biochemical responses of plants involved in defense mechanisms. In this respect, phenolic compounds, free amino acids in source leaves, protein contents, some secondary metabolites, and polyamines were found to increase, while chlorophyll content and photosynthetic activity and the number of chemical compounds were reduced as a consequence of phytoplasma infection. Therefore, the objective of this study was to review the chemical composition changes in phytoplasma-infected plants.

scholarly journals Cooperative Immune Suppression by Escherichia coli and Shigella Effector Proteins

2018 ◽  
Vol 86 (4) ◽  
Author(s):  
Maarten F. de Jong ◽  
Neal M. Alto
Keyword(s):  
Escherichia Coli ◽  
Defense Mechanisms ◽  
Immune Defense ◽  
Effector Proteins ◽  
Innate Immune ◽  
Host Cells ◽  
Secretion Systems ◽  
Content Type ◽  
E Coli ◽  
Type Iii Secretion Systems

ABSTRACT The enteric attaching and effacing (A/E) pathogens enterohemorrhagic Escherichia coli (EHEC) and enteropathogenic E. coli (EPEC) and the invasive pathogens enteroinvasive E. coli (EIEC) and Shigella encode type III secretion systems (T3SS) used to inject effector proteins into human host cells during infection. Among these are a group of effectors required for NF-κB-mediated host immune evasion. Recent studies have identified several effector proteins from A/E pathogens and EIEC/ Shigella that are involved in suppression of NF-κB and have uncovered their cellular and molecular functions. A novel mechanism among these effectors from both groups of pathogens is to coordinate effector function during infection. This cooperativity among effector proteins explains how bacterial pathogens are able to effectively suppress innate immune defense mechanisms in response to diverse classes of immune receptor signaling complexes (RSCs) stimulated during infection.

Screening of novel chemical compounds as possible inhibitors of carbonic anhydrase and photosynthetic activity of photosystem II

2014 ◽  
Vol 137 ◽  
pp. 156-167 ◽  
Author(s):  
Mehmet Sayım Karacan ◽  
Sergei K. Zharmukhamedov ◽  
Serhat Mamaş ◽  
Elena V. Kupriyanova ◽  
Alexandr V. Shitov ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Carbonic Anhydrase ◽  
Photosynthetic Activity ◽  
Chemical Compounds

Field Studies of DCMU-Enhanced Fluorescence as an Index of in situ Phytoplankton Photosynthetic Activity

1980 ◽  
Vol 37 (6) ◽  
pp. 1028-1031 ◽  
Author(s):  
Suzanne Roy ◽  
Louis Legendre
Keyword(s):  
Photosynthetic Activity ◽  
Field Work ◽  
Field Studies ◽  
Gulf Of Guinea ◽  
Lawrence Estuary ◽  
Technical Problems ◽  
Lower Light ◽  
St Lawrence Estuary ◽  
Composition Changes

Comparison between the increase in fluorescence caused by DCMU (FD/FN: ratio of DCMU-enhanced to normal fluorescence) and the specific photosynthetic rate (P/B: photosynthetic activity per unit chlorophyll a) in the St. Lawrence Estuary showed that no overall correlation could be established between P/B and FD/FN, although there were significant correlations between these two variables on short transects. This reflected perhaps environmental and species composition changes. FD/FN vertical profiles in the Gulf of St. Lawrence and the Gulf of Guinea showed a characteristic increase with depth, as seen in laboratory cultures with a decrease in light intensity. This could be related to photosynthetic efficiency which is known to increase at lower light intensities. Technical problems involving the use of FD/FN as an estimator of P/B are also discussed. Further investigations are required before this fluorescence technique can be used regularly in field work to estimate photosynthetic activity.Key words: DCMU, fluorescence, photosynthesis, phytoplankton, St. Lawrence Estuary, Gulf of Guinea

scholarly journals Influence of abscisic acid and other plant growth regulators on citrus defense mechanisms to salt stress

2003 ◽  
Vol 1 (1) ◽  
pp. 59 ◽  
Author(s):  
V. Arbona Mengual ◽  
M.L. Foó Serra ◽  
P. Escrig Marín ◽  
A.J. Marco Casanova ◽  
J.A. Jacas Miret ◽  
...  
Keyword(s):  
Abscisic Acid ◽  
Salt Stress ◽  
Plant Growth ◽  
Jasmonic Acid ◽  
Growth Regulators ◽  
Ethylene Production ◽  
Defense Mechanisms ◽  
Photosynthetic Activity ◽  
High Reduction ◽  
Chloride Accumulation

Citrus yield and growth are deeply affected by salinity. In the present work we have studied the effectiveness of differentplant growth regulators such as abscisic acid, jasmonic acid and 8’-methylene methyl abscissate in protectingcitrus from salt-induced damage. Plants of Salustiana cultivar grafted onto Carrizo citrange were used for this purpose.Plants were watered with 100 mM NaCl and leaf abscission, ethylene production, chloride accumulation and net photosyntheticrate were measured. Non-treated plants showed a dramatic drop in photosynthetic activity in response tosalinity, an increase in leaf ethylene production and a high abscission rate as a result of a massive leaf chloride accumulation.Plants treated with jasmonic acid or 8’-methylene methyl abscisate did not show any physiological changein response to salt stress. However, plants treated with abscisic acid showed a high reduction in the parameters considered.These results suggest that abscisic acid plays a role in modifying citrus physiological behaviour in responseto salinity and could be helpful in their acclimation to saline conditions

scholarly journals Identification of Novel Host Interactors of Effectors Secreted by Salmonella and Citrobacter

mSystems ◽  
2016 ◽  
Vol 1 (4) ◽  
Author(s):  
Ryan L. Sontag ◽  
Ernesto S. Nakayasu ◽  
Roslyn N. Brown ◽  
George S. Niemann ◽  
Michael A. Sydor ◽  
...  
Keyword(s):  
Host Cell ◽  
Type Iii Secretion ◽  
Defense Mechanisms ◽  
Pathogenic Bacteria ◽  
Effector Proteins ◽  
Host Cells ◽  
Secretion Systems ◽  
Type Iii ◽  
Cell Cytosol ◽  
Host Cell Cytosol

ABSTRACT During infection, pathogenic bacteria face an adverse environment of factors driven by both cellular and humoral defense mechanisms. To help evade the immune response and ultimately proliferate inside the host, many bacteria evolved specialized secretion systems to deliver effector proteins directly into host cells. Translocated effector proteins function to subvert host defense mechanisms. Numerous pathogenic bacteria use a specialized secretion system called type III secretion to deliver effectors into the host cell cytosol. Here, we identified 75 new host targets of Salmonella and Citrobacter effectors, which will help elucidate their mechanisms of action. Many pathogenic bacteria of the family Enterobacteriaceae use type III secretion systems to inject virulence proteins, termed “effectors,” into the host cell cytosol. Although host-cellular activities of several effectors have been demonstrated, the function and host-targeted pathways of most of the effectors identified to date are largely undetermined. To gain insight into host proteins targeted by bacterial effectors, we performed coaffinity purification of host proteins from cell lysates using recombinant effectors from the Enterobacteriaceae intracellular pathogens Salmonella enterica serovar Typhimurium and Citrobacter rodentium. We identified 54 high-confidence host interactors for the Salmonella effectors GogA, GtgA, GtgE, SpvC, SrfH, SseL, SspH1, and SssB collectively and 21 interactors for the Citrobacter effectors EspT, NleA, NleG1, and NleK. We biochemically validated the interaction between the SrfH Salmonella protein and the extracellular signal-regulated kinase 2 (ERK2) host protein kinase, which revealed a role for this effector in regulating phosphorylation levels of this enzyme, which plays a central role in signal transduction. IMPORTANCE During infection, pathogenic bacteria face an adverse environment of factors driven by both cellular and humoral defense mechanisms. To help evade the immune response and ultimately proliferate inside the host, many bacteria evolved specialized secretion systems to deliver effector proteins directly into host cells. Translocated effector proteins function to subvert host defense mechanisms. Numerous pathogenic bacteria use a specialized secretion system called type III secretion to deliver effectors into the host cell cytosol. Here, we identified 75 new host targets of Salmonella and Citrobacter effectors, which will help elucidate their mechanisms of action.

scholarly journals ADUBAÇÃO NITROGENADA NA SEVERIDADE DE DOENÇAS FOLIARES, PRODUTIVIDADE E RESPOSTAS BIOQUÍMICAS EM HÍBRIDOS DE MILHO

2018 ◽  
Vol 17 (1) ◽  
pp. 1
Author(s):  
JAÍZA FRANCISCA RIBEIRO CHAGAS ◽  
GIL RODRIGUES DOS SANTOS ◽  
RODRIGO VERAS DA COSTA ◽  
JOHNATHAN FONTES ALVES ◽  
ILDON RODRIGUES DO NASCIMENTO
Keyword(s):  
Amino Acids ◽  
Zea Mays ◽  
Nitrogen Fertilization ◽  
Defense Mechanisms ◽  
Block Design ◽  
Maize Hybrids ◽  
Biochemical Responses ◽  
Progress Curve ◽  
Randomized Complete Block Design ◽  
High Doses

RESUMO – O nitrogênio participa de muitos processos metabólicos relacionados aos mecanismos de defesa das plantas, podendo além de beneficiar diretamente a produtividade, auxiliar na tolerância a doenças. Objetivou-se avaliar o efeito da adubação nitrogenada de cobertura na severidade de doenças foliares, na produtividade e nas respostas bioquímicas em híbridos de milho. Dois experimentos foram conduzidos em campo, com delineamento experimental de blocos casualizados, com tratamentos dispostos em arranjo de parcelas subdivididas, com três repetições. As parcelas foram constituídas pelos híbridos e as subparcelas, pelas doses de nitrogênio. Determinou-se a área abaixo da curva de progresso da doença (AACPD), a massa de mil grãos (g), a produtividade em kg ha-1, os teores das enzimas superóxido dismutase (SOD) e catalase (CAT), o aminoácido prolina e os aminoácidos solúveis totais. A maioria dos híbridos avaliados apresentaram resposta a mancha-de-bipolaris e a antracnose-foliar mais severa nas menores doses de nitrogênio testadas (36 e 40 kg ha-1). A ferrugem-polissora foi mais severa em condições de alto nitrogênio para os híbridos ATTACK, TRAKTOR, BM 2202 e 30F53YH. A massa de mil grãos não foi influenciada pelas diferenças nas doses. A produtividade dos híbridos 2B710 e 3H842 foi maior na dose de 180 kg ha-1. A catalase e a prolina alcançaram maior e menor atividade, respectivamente, onde ocorreu maior severidade da mancha-de-bipolaris nos híbridos 2B710 e AG7088PROX. Os aminoácidos foram encontrados em maiores quantidades nas doses altas de nitrogênio. Palavras-chave: Zea mays, nutrição, nitrogênio, patógeno, mecanismos de defesa. NITROGEN FERTILIZATION IN LEAF DISEASE SEVERITY, PRODUCTIVITY AND BIOCHEMICAL RESPONSES IN MAIZE HYBRIDS ABSTRACT - Nitrogen participates in many metabolic processes related to the defense mechanisms of plants, besides being able directly to benefit the productivity, to aid in the tolerance to diseases. The objective of this study was to evaluate the effect of nitrogen fertilization on the severity of leaf diseases, productivity and biochemical responses in maize hybrids. Two experiments were conducted in the field, with a randomized complete block design, with treatments arranged in split plot arrangement, and three replications. The plots were composed of the hybrids and the subplots by the nitrogen doses. The area under the disease progress curve (AACPD), one thousand grain mass (g), yield in kg ha-1, levels of the enzymes superoxide dismutase (SOD) and catalase (CAT), the amino acid proline and the total soluble amino acids were determined. Most of the evaluated hybrids showed a more severe bipolaris spot and foliar anthracnose response at the lowest nitrogen doses tested (36 and 40 kg ha-1). Polissora rust was more severe under high nitrogen conditions for the hybrids ATTACK, TRAKTOR, BM 2202 and 30F53YH. The mass of one thousand grains was not influenced by the differences in the doses. The productivity of the hybrids 2B710 and 3H842 was higher at the dose of 180 kg ha-1. Catalase and proline reached higher and lower activity, respectively, where the highest severity of the bipolaris spot occurred in hybrids 2B710 and AG7088PROX. Amino acids were found in higher amounts at high doses of nitrogen. Keywords: Zea mays, nutrition, nitrogen, pathogen, defense mechanisms.

scholarly journals Widespread targeting of development-related host transcription factors by phytoplasma effectors

2020 ◽  
Author(s):  
Miguel Correa Marrero ◽  
Sylvain Capdevielle ◽  
Weijie Huang ◽  
Marco Busscher ◽  
Jacqueline Busscher-Lange ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Protein Interaction ◽  
Protein Interaction Network ◽  
Pathogenic Bacteria ◽  
Molecular Mechanisms ◽  
Interaction Network ◽  
Effector Proteins ◽  
Insect Vector ◽  
Plant Host ◽  
Phytoplasma Infection

1AbstractPhytoplasmas are pathogenic bacteria that reprogram plant host development in order to attract their insect vectors to disseminate. Previous studies have characterized a few different phytoplasma effector proteins that supress specific transcription factors. However, these are only a small fraction of the potential effectors used by phytoplasmas, meaning that the molecular mechanisms through which phytoplasmas manipulate their hosts are largely uncharacterized. To obtain further insights into the phytoplasma infection mechanisms, we generated a protein-protein interaction network between a broad set of phytoplasma effectors and a large collection of Arabidopsis thaliana transcription factors and transcriptional regulators. We found widespread, but unique, interactions with host transcription factors by phytoplasma effectors, especially those related to developmental processes. In particular, many unrelated effectors target TCP transcription factors, which play roles in plant development and immunity. Comparison with other host-pathogen protein interaction networks shows that phytoplasma effectors have unusual targets, and indicates that phytoplasmas have evolved a unique and unusual infection strategy. This study provides a rich and solid data source that can be used to predict functional effects of individual effectors and as a guide for detailed studies of individual effectors in the future, as well as insights into the underlying molecular mechanisms of phytoplasma infection.2Significance statementThis work shows that the effectors of phytoplasma, a bacterial plant pathogen, show pervasive interactions with development-related host transcription factors, providing a way to take over plant growth and development in favor of the pathogen and its insect vector. The obtained comprehensive protein interaction network and showcase of the potential biological consequences of a selected effector advance our understanding of phytoplasma-host interactions and provide guidance for further study.

scholarly journals Common Ragweed (Ambrosia artemisiifolia L.) Causes Severe Yield Losses in Soybean and Impairs Bradyrhizobium japonicum Infection

Agronomy ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1616
Author(s):  
Rea Maria Hall ◽  
Bernhard Urban ◽  
Helmut Wagentristl ◽  
Gerhard Karrer ◽  
Anna Winter ◽  
...  
Keyword(s):  
Bradyrhizobium Japonicum ◽  
Yield Loss ◽  
Chemical Compounds ◽  
Ambrosia Artemisiifolia ◽  
Yield Losses ◽  
Management Options ◽  
Soybean Yield ◽  
Common Ragweed ◽  
Arable Fields ◽  
The Mean

Ambrosia artemisiifolia L. (Asteraceae), known as common ragweed, is an annual herbaceous species native to North America that has become one of the most economically important weeds in arable fields throughout Central Europe. Its large ecological amplitude enables the species to become established in several types of environments, and management options to effectively contain its spread are limited due to a lack of efficacy, high cost, or lack of awareness. In the last decade, in particular, soybean fields have been severely affected by common ragweed invasion. However, until now, information on the yield-decreasing effects of the plant has been scarce. Therefore, the aim of this study was to evaluate the competition effects of common ragweed on (1) soybean growth (aboveground/belowground), (2) the yield of two different soybean cultivars, and (3) the nodulation potential. Based on a greenhouse and biennial field trial, we found that in plots with the highest common ragweed biomass, the soybean yield loss accounted for 84% compared to the weed-free control, on average. The number of nodules, in addition to the mean nodule weight, which are tightly correlated with soybean yield, were significantly reduced by the presence of common ragweed. Just one common ragweed plant per square meter reduced the number of nodules by 56%, and consequently led to a decrease in yield of 18%. Although it has been reported that the genus Ambrosia produces and releases several types of secondary metabolites, little is known about the influence of these chemical compounds on soybean growth and nodulation. Thus, there is substantial need for research to understand the mechanisms behind the interaction between common ragweed and soybean, with a view to finding new approaches for improved common ragweed control, thereby protecting soybean and other crops against substantial yield losses.

scholarly journals Potentiation of Cytokine-Mediated Restriction ofLegionellaIntracellular Replication by a Dot/Icm-Translocated Effector

2019 ◽  
Vol 201 (14) ◽  
Author(s):  
Tshegofatso Ngwaga ◽  
Alex J. Hydock ◽  
Sandhya Ganesan ◽  
Stephanie R. Shames
Keyword(s):  
Legionella Pneumophila ◽  
Defense Mechanisms ◽  
Effector Proteins ◽  
Host Cells ◽  
Content Type ◽  
Host Restriction ◽  
Type Iv ◽  
Legionnaires Disease ◽  
Ifn Γ ◽  
Necrosis Factor

ABSTRACTLegionella pneumophilais ubiquitous in freshwater environments, where it replicates within unicellular protozoa. However,L. pneumophilais also an accidental human pathogen that can cause Legionnaires’ disease in immunocompromised individuals by uncontrolled replication within alveolar macrophages. To replicate within eukaryotic phagocytes,L. pneumophilautilizes a Dot/Icm type IV secretion system to translocate a large arsenal of over 300 effector proteins directly into host cells. In mammals, translocated effectors contribute to innate immune restriction ofL. pneumophila. We found previously that the effector LegC4 is important forL. pneumophilareplication within a natural host protist but is deleterious to replication in a mouse model of Legionnaires’ disease. In the present study, we used cultured mouse primary macrophages to investigate how LegC4 attenuatesL. pneumophilareplication. We found that LegC4 enhanced restriction ofL. pneumophilareplication within macrophages activated with tumor necrosis factor (TNF) or interferon gamma (IFN-γ). In addition, expression oflegC4was sufficient to restrictLegionella longbeachaereplication within TNF- or IFN-γ-activated macrophages. Thus, this study demonstrates that LegC4 contributes toL. pneumophilaclearance from healthy hosts by potentiating cytokine-mediated host defense mechanisms.IMPORTANCELegionellaspp. are natural pathogens of protozoa and accidental pathogens of humans. Innate immunity in healthy individuals effectively controlsLegionellainfection due in part to rapid and robust production of proinflammatory cytokines resulting from detection of Dot/Icm-translocated substrates, including effectors. Here, we demonstrate that the effector LegC4 enhances proinflammatory host restriction ofLegionellaby macrophages. These data suggest that LegC4 may augment proinflammatory signaling or antimicrobial activity of macrophages, a function that has not previously been observed for another bacterial effector. Further insight into LegC4 function will likely reveal novel mechanisms to enhance immunity against pathogens.

scholarly journals Recognitional Specificity and Evolution in the Tomato–Cladosporium fulvum Pathosystem

2009 ◽  
Vol 22 (10) ◽  
pp. 1191-1202 ◽  
Author(s):  
B. B. H. Wulff ◽  
A. Chakrabarti ◽  
D. A. Jones
Keyword(s):  
Defense Mechanisms ◽  
Extracellular Proteins ◽  
Effector Proteins ◽  
Cladosporium Fulvum ◽  
Host Proteins ◽  
Pathogen Effectors ◽  
Passalora Fulva ◽  
Pathogen Effector ◽  
Mold Fungus ◽  
Avr Genes

The interactions between plants and many biotrophic or hemibiotrophic pathogens are controlled by receptor proteins in the host and effector proteins delivered by the pathogen. Pathogen effectors facilitate pathogen growth through the suppression of host defenses and the manipulation of host metabolism, but recognition of a pathogen-effector protein by a host receptor enables the host to activate a suite of defense mechanisms that limit pathogen growth. In the tomato (Lycopersicon esculentum syn. Solanum lycopersicum)–Cladosporium fulvum (leaf mold fungus syn. Passalora fulva) pathosystem, the host receptors are plasma membrane–anchored, leucine-rich repeat, receptor-like proteins encoded by an array of Cf genes conferring resistance to C. fulvum. The pathogen effectors are mostly small, secreted, cysteine-rich, but otherwise largely dissimilar, extracellular proteins encoded by an array of avirulence (Avr) genes, so called because of their ability to trigger resistance and limit pathogen growth when the corresponding Cf gene is present in tomato. A number of Cf and Avr genes have been isolated, and details of the complex molecular interplay between tomato Cf proteins and C. fulvum effector proteins are beginning to emerge. Each effector appears to have a different role; probably most bind or modify different host proteins, but at least one has a passive role masking the pathogen. It is, therefore, not surprising that each effector is probably detected in a distinct and specific manner, some by direct binding, others as complexes with host proteins, and others via their modification of host proteins. The two papers accompanying this review contribute further to our understanding of the molecular specificity underlying effector perception by Cf proteins. This review, therefore, focuses on our current understanding of recognitional specificity in the tomato–C. fulvum pathosystem and highlights some of the critical questions that remain to be addressed. It also addresses the evolutionary causes and consequences of this specificity.

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