scholarly journals Arabidopsis thaliana Immunity-Related Compounds Modulate Disease Susceptibility in Barley

Agronomy ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 142 ◽  
Author(s):  
Miriam Lenk ◽  
Marion Wenig ◽  
Felicitas Mengel ◽  
Finni Häußler ◽  
A. Vlot
Keyword(s):  
Pathogenic Bacteria ◽  
Disease Susceptibility ◽  
Model Systems ◽  
Cereal Crops ◽  
Pyrenophora Teres ◽  
Cereal Crop ◽  
Barley Leaves ◽  
Biotrophic Pathogens ◽  
Defence Signalling ◽  
Related Compounds

Plants are exposed to numerous pathogens and fend off many of these with different phytohormone signalling pathways. Much is known about defence signalling in the dicotyledonous model plant Arabidopsisthaliana, but it is unclear to which extent knowledge from model systems can be transferred to monocotyledonous plants, including cereal crops. Here, we investigated the defence-inducing potential of Arabidopsis resistance-inducing compounds in the cereal crop barley. Salicylic acid (SA), folic acid (Fol), and azelaic acid (AzA), each inducing defence against (hemi-)biotrophic pathogens in Arabidopsis, were applied to barley leaves and the treated and systemic leaves were subsequently inoculated with Xanthomonastranslucens pv. cerealis (Xtc), Blumeria graminis f. sp. hordei (powdery mildew, Bgh), or Pyrenophora teres. Fol and SA reduced Bgh propagation locally and/or systemically, whereas Fol enhanced Xtc growth in barley. AzA reduced Bgh propagation systemically and enhanced Xtc growth locally. Neither SA, Fol, nor AzA influenced lesion sizes caused by the necrotrophic fungus P. teres, suggesting that the tested compounds exclusively affected growth of (hemi-)biotrophic pathogens in barley. In addition to SA, Fol and AzA might thus act as resistance-inducing compounds in barley against Bgh, although adverse effects on the growth of pathogenic bacteria, such as Xtc, are possible.

scholarly journals Pathogen effector recognition-dependent association of NRG1 with EDS1 and SAG101 in TNL receptor immunity

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xinhua Sun ◽  
Dmitry Lapin ◽  
Joanna M. Feehan ◽  
Sara C. Stolze ◽  
Katharina Kramer ◽  
...  
Keyword(s):  
Disease Susceptibility ◽  
Nucleotide Binding ◽  
Molecular Evidence ◽  
Pathogen Effectors ◽  
Pathogen Effector ◽  
Family Protein ◽  
Activated State ◽  
Defence Signalling ◽  
Effector Recognition ◽  
Dependent Interaction

AbstractPlants utilise intracellular nucleotide-binding, leucine-rich repeat (NLR) immune receptors to detect pathogen effectors and activate local and systemic defence. NRG1 and ADR1 “helper” NLRs (RNLs) cooperate with enhanced disease susceptibility 1 (EDS1), senescence-associated gene 101 (SAG101) and phytoalexin-deficient 4 (PAD4) lipase-like proteins to mediate signalling from TIR domain NLR receptors (TNLs). The mechanism of RNL/EDS1 family protein cooperation is not understood. Here, we present genetic and molecular evidence for exclusive EDS1/SAG101/NRG1 and EDS1/PAD4/ADR1 co-functions in TNL immunity. Using immunoprecipitation and mass spectrometry, we show effector recognition-dependent interaction of NRG1 with EDS1 and SAG101, but not PAD4. An EDS1-SAG101 complex interacts with NRG1, and EDS1-PAD4 with ADR1, in an immune-activated state. NRG1 requires an intact nucleotide-binding P-loop motif, and EDS1 a functional EP domain and its partner SAG101, for induced association and immunity. Thus, two distinct modules (NRG1/EDS1/SAG101 and ADR1/EDS1/PAD4) mediate TNL receptor defence signalling.

scholarly journals Disruption of VirB6 Paralogs in Anaplasma phagocytophilum Attenuates Its Growth

2020 ◽  
Vol 202 (23) ◽  
Author(s):  
Francy L. Crosby ◽  
Ulrike G. Munderloh ◽  
Curtis M. Nelson ◽  
Michael J. Herron ◽  
Anna M. Lundgren ◽  
...  
Keyword(s):  
Anaplasma Phagocytophilum ◽  
Pathogenic Bacteria ◽  
Tandem Repeats ◽  
Model Systems ◽  
Accession Number ◽  
Secretion Systems ◽  
Altered Expression ◽  
Content Type ◽  
Obligate Intracellular

ABSTRACT Many pathogenic bacteria translocate virulence factors into their eukaryotic hosts by means of type IV secretion systems (T4SS) spanning the inner and outer membranes. Genes encoding components of these systems have been identified within the order Rickettsiales based upon their sequence similarities to other prototypical systems. Anaplasma phagocytophilum strains are obligate intracellular, tick-borne bacteria that are members of this order. The organization of these components at the genomic level was determined in several Anaplasma phagocytophilum strains, showing overall conservation, with the exceptions of the virB2 and virB6 genes. The virB6 loci are characterized by the presence of four virB6 copies (virB6-1 through virB6-4) arranged in tandem within a gene cluster known as the sodB-virB operon. Interestingly, the virB6-4 gene varies significantly in length among different strains due to extensive tandem repeats at the 3′ end. To gain an understanding of how these enigmatic virB6 genes function in A. phagocytophilum, we investigated their expression in infected human and tick cells. Our results show that these genes are expressed by A. phagocytophilum replicating in both cell types and that VirB6-3 and VirB6-4 proteins are surface exposed. Analysis of an A. phagocytophilum mutant carrying the Himar1 transposon within the virB6-4 gene demonstrated that the insertion not only disrupted its expression but also exerted a polar effect on the sodB-virB operon. Moreover, the altered expression of genes within this operon was associated with the attenuated in vitro growth of A. phagocytophilum in human and tick cells, indicating the importance of these genes in the physiology of this obligate intracellular bacterium in such different environments. IMPORTANCE Knowledge of the T4SS is derived from model systems, such as Agrobacterium tumefaciens. The structure of the T4SS in Rickettsiales differs from the classical arrangement. These differences include missing and duplicated components with structural alterations. Particularly, two sequenced virB6-4 genes encode unusual C-terminal structural extensions resulting in proteins of 4,322 (GenBank accession number AGR79286.1) and 9,935 (GenBank accession number ANC34101.1>) amino acids. To understand how the T4SS is used in A. phagocytophilum, we describe the expression of the virB6 paralogs and explore their role as the bacteria replicate within its host cell. Conclusions about the importance of these paralogs for colonization of human and tick cells are supported by the deficient phenotype of an A. phagocytophilum mutant isolated from a sequence-defined transposon insertion library.

scholarly journals PTK1, a Mitogen-Activated-Protein Kinase Gene, Is Required for Conidiation, Appressorium Formation, and Pathogenicity of Pyrenophora teres on Barley

2001 ◽  
Vol 14 (2) ◽  
pp. 116-125 ◽  
Author(s):  
M. Carmen Ruiz-Roldán ◽  
Frank J. Maier ◽  
Wilhelm Schäfer
Keyword(s):  
Protein Kinases ◽  
Mitogen Activated Protein Kinase ◽  
Predicted Amino Acid Sequence ◽  
Complete Medium ◽  
Pyrenophora Teres ◽  
Hordeum Vulgare L ◽  
Degenerate Primers ◽  
Kinase Gene ◽  
Mitogen Activated Protein ◽  
Barley Leaves

Mitogen-activated protein kinases (MAPKs) are a group of protein kinases that execute a wide variety of roles in cellular signal transduction pathways such as osmoregulation, cell wall biosynthesis, growth, and differentiation. A polymerase chain reaction (PCR) with degenerate primers based on conserved regions of known MAPKs was used to clone the MAPK gene PTK1 from the leaf pathogen Pyrenophora teres (anamorph Drechslera teres), the causal agent of net blotch of barley (Hordeum vulgare L.). The predicted amino acid sequence shows high homology with MAPKs from other phytopathogenic fungi. The gene is present in the genome as a single copy. PTK1 is expressed during in vitro growth on complete medium, under conidiation-inducing conditions and during infection of barley leaves, as shown by reverse transcription-PCR studies. In order to assess the role of PTK1 in the life cycle of P. teres, targeted gene disruption was conducted. Mutants carrying an interrupted copy of the gene were deficient in conidiation, did not form appressoria on glass surfaces or on barley leaves, lost their ability to infect barley leaves, and could not colonize host tissues following artificial wounding.

Comparative Phytotoxicity Assays of the Herbicide Alloxydim and Its Main Identified Photoproduct in Cereal and Broadleaves Crops

Weed Science ◽  
2015 ◽  
Vol 63 (2) ◽  
pp. 377-387 ◽  
Author(s):  
Pilar Sandín-España ◽  
Beatriz Sevilla-Morán ◽  
Mercedes Villarroya-Ferruz ◽  
José L. Alonso-Prados ◽  
M. Inés Santín-Montanyá
Keyword(s):  
Human Health ◽  
Active Substance ◽  
Degradation Products ◽  
Model Systems ◽  
Parent Substance ◽  
Cereal Crops ◽  
Rapid Degradation ◽  
Soil Model ◽  
Plant Cuticles ◽  
Grass Weed

When herbicides are sprayed in the field, a proportion of the herbicide falls onto leaves and soil surfaces, where it can be exposed to sunlight, generating photoproducts that can be more toxic and/or persistent than the parent substance and affect human health and the environment. The aim of this study was to identify the photoproducts of the herbicide alloxydim in leaf and soil model systems and to perform phytotoxicity studies. Alloxydim was rapidly photodegraded in systems simulating plant cuticles and soil surfaces, with half-lives ranging from 1 to 30 min. The main by-product, identified by LC-Qtof-MS as deallyoxylated alloxydim, was more stable than the active substance. The EC50values on root lengths of different varieties of wheat plants and one grass weed ranged from 0.38 to 0.50 mg L−1for alloxydim. In contrast, the EC50values for deallyoxylated alloxydim ranged from 94 to 600 mg L−1in the same species and in crops where the herbicide was applied. Special attention should be given to alloxydim degradation products because of the rapid degradation of this herbicide. Comparative bioassay studies between alloxydim and its photostable by-product showed that the by-product presents low phytotoxicity, whereas alloxydim can cause injury to neighboring and succeeding cereal crops.

scholarly journals Screening of Probiotic Activities of Forty-Seven Strains of Lactobacillus spp. by In Vitro Techniques and Evaluation of the Colonization Ability of Five Selected Strains in Humans

1999 ◽  
Vol 65 (11) ◽  
pp. 4949-4956 ◽  
Author(s):  
C. N. Jacobsen ◽  
V. Rosenfeldt Nielsen ◽  
A. E. Hayford ◽  
P. L. Møller ◽  
K. F. Michaelsen ◽  
...  
Keyword(s):  
Washout Period ◽  
Pathogenic Bacteria ◽  
Model Systems ◽  
In Vivo Studies ◽  
Enzyme Analysis ◽  
Restriction Enzyme Analysis ◽  
Fecal Samples ◽  
Freeze Dried

ABSTRACT The probiotic potential of 47 selected strains ofLactobacillus spp. was investigated. The strains were examined for resistance to pH 2.5 and 0.3% oxgall, adhesion to Caco-2 cells, and antimicrobial activities against enteric pathogenic bacteria in model systems. From the results obtained in vitro, five strains,Lactobacillus rhamnosus 19070-2, L. reuteri DSM 12246, L. rhamnosus LGG, L. delbrueckii subsp.lactis CHCC 2329, and L. casei subsp.alactus CHCC 3137, were selected for in vivo studies. The daily consumption by 12 healthy volunteers of two doses of 1010 freeze-dried bacteria of the selected strains for 18 days was followed by a washout period of 17 days. Fecal samples were taken at days 0 and 18 and during the washout period at days 5 and 11.Lactobacillus isolates were initially identified by API 50CHL and internal transcribed spacer PCR, and their identities were confirmed by restriction enzyme analysis in combination with pulsed-field gel electrophoresis. Among the tested strains, L. rhamnosus 19070-2, L. reuteri DSM 12246, and L. rhamnosus LGG were identified most frequently in fecal samples; they were found in 10, 8, and 7 of the 12 samples tested during the intervention period, respectively, whereas reisolations were less frequent in the washout period. The bacteria were reisolated in concentrations from 105 to 108 cells/g of feces. Survival and reisolation of the bacteria in vivo appeared to be linked to pH tolerance, adhesion, and antimicrobial properties in vitro.

THE USE OF CEREAL GRAINS AS COMPANION CROPS IN DRYLAND FORAGE CROP ESTABLISHMENT

1960 ◽  
Vol 40 (1) ◽  
pp. 81-93 ◽  
Author(s):  
M. R. Kilcher ◽  
D. H. Heinrichs
Keyword(s):  
Cereal Grains ◽  
Cereal Crops ◽  
Cereal Crop ◽  
Crested Wheatgrass ◽  
Forage Crop ◽  
Crop Establishment ◽  
Arid Conditions ◽  
Cereal Grain ◽  
Companion Crop ◽  
Forage Yields

The effect of wheat, oats, barley, and spring rye as companion crops on the establishment of a perennial forage crop mixture consisting of crested wheatgrass, brome, and alfalfa under arid conditions compared to no companion crop was studied at Swift Current, Saskatchewan. Cereal companion crops reduced the vigour, stand, and subsequent early forage yields of the grass-alfalfa mixtures, but less so if the cereal crop and the forage crop were seeded separately at right-angles to one another. The method of harvesting the cereal companion crop also influenced the performance of the subsequent forage crop. Cutting the cereal crops at a height of 8 inches or more for grain resulted in better grass-alfalfa stands and yields than was obtained when the cereal crops were mowed at a 2-inch height for hay. The effect of kind of cereal grain on performance of the perennial forage differed little. Wider row spacings for the cross-seeded companion crops also resulted in a better stand and yield of the grass-alfalfa crop.

Fall-applied cattle manure did not provide nitrogen fertilizer value to spring cereal crops

2021 ◽  
pp. 1-4
Author(s):  
Leanne Ejack ◽  
Chih-Yu Hung ◽  
Joann K. Whalen
Keyword(s):  
Sandy Loam ◽  
Cattle Manure ◽  
Cereal Crops ◽  
Cereal Crop ◽  
Total N ◽  
Available N ◽  
Fertilizer Value ◽  
Spring Cereals ◽  
Loam Soil ◽  
Growing Conditions

Fall-applied manure may have nitrogen (N) fertilizer value for spring-seeded crops. We applied liquid or solid cattle manure to plots on a sandy-loam soil in southern Quebec in fall. The following spring, half of each plot received urea fertilizer before planting the spring cereal crop. Total N content of the spring cereal at tillering, flowering, and maturity was lower in subplots without urea, and yields were up to 183% less in the no-urea subplots, regardless of whether liquid or solid manure was applied in fall. Fall-applied manure did not provide plant-available N to spring cereals under our growing conditions.

An appraisal of cereal crop phenology modelling

1995 ◽  
Vol 75 (2) ◽  
pp. 329-341 ◽  
Author(s):  
C. F. Shaykewich
Keyword(s):  
Zea Mays L ◽  
Triticum Aestivum L ◽  
Weather Data ◽  
Cereal Crops ◽  
Cereal Crop ◽  
Degree Days ◽  
Hordeum Vulgare L ◽  
Crop Phenology ◽  
Climatological Station ◽  
Phenological Modelling

A review of responses of phenological development of cereal crops, primarily corn (Zea mays L.), wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.), to environmental conditions was conducted. Examples of how these studies have been used to model phenological development on the basis of weather data were given.It was concluded that the development rate of most species is a sigmoidal rather than a linear function of temperature. Consequently, phenological models assuming a linear relationship (e.g., degree–days) are inappropriate. Another consequence of the way plants respond to temperature is that the most precise phenological models will require use of temperature data over relatively short periods (e.g., 3 h), rather than just a daily mean temperature. Several suggestions regarding the ways standard climatological station data may be used in such phenological modelling are made.Phenological response to photoperiod was also reviewed, and methods of modelling this response were proposed. Key words: Phenology, temperature, photoperiod, modelling

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