scholarly journals A Small GTP-Binding Host Protein Is Required for Entry of Powdery Mildew Fungus into Epidermal Cells of Barley

2002 ◽  
Vol 128 (4) ◽  
pp. 1447-1454 ◽  
Author(s):  
Holger Schultheiss ◽  
Cornelia Dechert ◽  
Karl-Heinz Kogel ◽  
Ralph Hückelhoven
Keyword(s):  
Powdery Mildew ◽  
Epidermal Cells ◽  
Host Protein ◽  
Powdery Mildew Fungus ◽  
Gtp Binding

scholarly journals Differential Gene Expression in Individual Papilla-Resistant and Powdery Mildew-Infected Barley Epidermal Cells

2004 ◽  
Vol 17 (7) ◽  
pp. 729-738 ◽  
Author(s):  
Torben Gjetting ◽  
Timothy L. W. Carver ◽  
Leif Skøt ◽  
Michael F. Lyngkjær
Keyword(s):  
Gene Expression ◽  
Powdery Mildew ◽  
Single Cell ◽  
Pcr Amplification ◽  
Epidermal Cells ◽  
Powdery Mildew Fungus ◽  
Pathogenesis Related Protein ◽  
Infected Cells ◽  
Transcript Profiles ◽  
Microarray Expression

Resistance and susceptibility in barley to the powdery mildew fungus (Blumeria graminis f. sp. hordei) is determined at the single-cell level. Even in genetically compatible interactions, attacked plant epidermal cells defend themselves against attempted fungal penetration by localized responses leading to papilla deposition and reinforcement of their cell wall. This conveys a race-nonspecific form of resistance. However, this defense is not complete, and a proportion of penetration attempts succeed in infection. The resultant mixture of infected and uninfected leaf cells makes it impossible to relate powdery mildew-induced gene expression in whole leaves or even dissected epidermal tissues to resistance or susceptibility. A method for generating transcript profiles from individual barley epidermal cells was established and proven useful for analyzing resistant and successfully infected cells separately. Contents of single epidermal cells (resistant, infected, and unattacked controls) were collected, and after cDNA synthesis and PCR amplification, the resulting sample was hybridized to dot-blots spotted with genes, including some previously reported to be induced upon pathogen attack. Transcripts of several genes, (e.g., PR1a, encoding a pathogenesis related protein, and GLP4, encoding a germin-like protein) accumulated specifically in resistant cells, while GRP94, encoding a molecular chaperone, accumulated in infected cells. Thus, the single-cell method allows discrimination of transcript profiles from resistant and infected cells. The method will be useful for microarray expression profiling for simultaneous analysis of many genes.

Defense reactions of barley cultivars to an inappropriate forma specialis of the powdery mildew fungus of gramineous plants

1984 ◽  
Vol 62 (10) ◽  
pp. 2114-2117 ◽  
Author(s):  
Y. Tosa ◽  
J. Shishiyama
Keyword(s):  
Powdery Mildew ◽  
Colony Growth ◽  
Epidermal Cells ◽  
Colony Development ◽  
Powdery Mildew Fungus ◽  
Barley Cultivars ◽  
Cellular Defense ◽  
Defense Reactions ◽  
Forma Specialis ◽  
Fluorescent Cells

Cellular defense reactions in five barley cultivars against Erysiphe graminis f. sp. tritici were examined in the course of primary and secondary penetrations. In cv. Kairyobozu-mugi, 35% of infection attempts were stopped at fluorescent papillae, and the others (65%) induced fluorescing of epidermal cells, resulting in the failure of the formation of primary haustoria. In the other cultivars ('H.E.S.4', 'Russian No. 12', 'Goseshikoku', and 'Turkey 290') the penetration failures associated with fluorescent papillae reached 50–75%, but the infection attempts that induced the fluorescing of epidermal cells were fewer than 20%. Consequently 10–30% of the germlings that attempted penetration successfully formed normal primary haustoria 48 h after inoculation. In cv. Goseshikoku, cv. Russian No. 12, and cv. H.E.S.4, 50–75% of the epidermal cells that contained the primary haustoria were fluorescent 7 days after inoculation, and colony growth was severely restricted. In cv. Turkey 290 such fluorescent cells scarcely occurred and colonies developed comparatively well. On this cultivar conidia were produced 5–6 days after inoculation, but only in small quantities. This restriction of colony development was mainly attributable to the inhibition of the formation of secondary haustoria by fluorescent papillae. These results indicate that there are differences among barley cultivars in cellular defense reactions against the wheat powdery mildew fungus and suggest that the formation of papillae during the course of primary penetration is not necessarily an essential factor in the resistance of barley to this inappropriate forma specialis.

scholarly journals Tissue-Specific Superoxide Generation at Interaction Sites in Resistant and Susceptible Near-Isogenic Barley Lines Attacked by the Powdery Mildew Fungus (Erysiphe graminis f. sp. hordei)

1998 ◽  
Vol 11 (4) ◽  
pp. 292-300 ◽  
Author(s):  
Ralph Hückelhoven ◽  
Karl-Heinz Kogel
Keyword(s):  
Cell Death ◽  
Powdery Mildew ◽  
Mesophyll Cell ◽  
Epidermal Cells ◽  
Erysiphe Graminis ◽  
Time Range ◽  
Powdery Mildew Fungus ◽  
Hypersensitive Cell Death ◽  
Interaction Sites ◽  
Nbt Reduction

The pathogenesis-related, azide-insensitive generation of superoxide anions (O2 -) was comparatively analyzed in near-isogenic barley (Hordeum vulgare cv. Pallas) lines carrying the powdery mildew (Erysiphe graminis f. sp. hordei) resistance genes Mla12, Mlg, and mlo5, respectively, by the microscopic detection of nitroblue tetra-zolium (NBT) reduction to dark blue formazan dyes. These genes govern fungal arrest at different stages of the interaction: (i) at the penetration stage within cell wall appositions (papillae) leaving the attacked cell alive (mlo); (ii) within papillae of cells that subsequently undergo a hypersensitive cell death (HR) (Mlg); or (iii) after penetration by a subsequent HR (Mla12). The susceptible parent line Pallas showed a transient O2 - generation in penetrated epidermal cells at 18 h after inoculation (hai), whereas epidermal cells of the resistant BCPMla12 produced O2 - over a longer time range (by 18 to 36 hai) preceding cell death. No oxidative burst was detected in association with penetration resistance due to effective papillae (BCPMlg and BCPmlo5) although Mlg specified an HR subsequent to fungal arrest. Hence, O2 - generation in attacked epidermal cells was a result of fungal penetration of the host cell walls and subsequent contact with the host plasma membrane, and not a requirement for HR elicitation. O2 - generation in the mesophyll tissue beneath attacked cells was associated with the response mediated by the genes Mla12 and Mlg. However, only BCPMla12 showed mesophyll cell death. The data indicate that, in barley, O2 - accumulation is not a single key determinant of HR in response to a powdery mildew attack.

scholarly journals A Barley ROP GTPase ACTIVATING PROTEIN Associates with Microtubules and Regulates Entry of the Barley Powdery Mildew Fungus into Leaf Epidermal Cells

2011 ◽  
Vol 23 (6) ◽  
pp. 2422-2439 ◽  
Author(s):  
Caroline Hoefle ◽  
Christina Huesmann ◽  
Holger Schultheiss ◽  
Frederik Börnke ◽  
Götz Hensel ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Epidermal Cells ◽  
Gtpase Activating Protein ◽  
Powdery Mildew Fungus ◽  
Barley Powdery Mildew ◽  
Rop Gtpase

scholarly journals A Barley Powdery Mildew Fungus Non-Autonomous Retrotransposon Encodes a Peptide that Supports Penetration Success on Barley

2018 ◽  
Author(s):  
Mathias Nottensteiner ◽  
Bernd Zechmann ◽  
Christopher McCollum ◽  
Ralph Hückelhoven
Keyword(s):  
Powdery Mildew ◽  
Host Cell ◽  
Plant Immunity ◽  
Epidermal Cells ◽  
Bimolecular Fluorescence Complementation ◽  
Transcriptional Gene Silencing ◽  
In Planta ◽  
Powdery Mildew Fungus ◽  
Microtubule Organization ◽  
Rop Gtpase

ABSTRACTPlant immunity is overcome by pathogens by the means of secreted effectors. Host effector targets might be proteins acting in pathogen defense or serve demands of the pathogen. The barley ROP GTPase HvRACB is involved in entry of the powdery mildew fungusBlumeria graminisf.sp.hordei (Bgh)into barley epidermal cells. We found that HvRACB interacts with theROP-interactive peptide 1 (ROPIP1) that is encoded on the active non-long terminal repeat retroelement Eg-R1 ofBgh. Over-expression of ROPIP1 in barley epidermal cells and host-induced post-transcriptional gene silencing (HIGS) ofROPIP1suggested that ROPIP1 is involved in virulence ofBgh. Bimolecular fluorescence complementation and co-localization supported that ROPIP1 can interact with activated HvRACB in planta. We show that ROPIP1 is expressed byBghon barley and translocated into the cytoplasm of infected barley cells. ROPIP1 is recruited to microtubules upon co-expression of MICROTUBULE ASSOCIATED ROP GTPase ACTIVATING PROTEIN (HvMAGAP1) and can destabilize cortical microtubules.BghROPIP might target HvRACB and manipulate host cell microtubule organization for facilitated host cell entry. Data suggest a possible neo-functionalization of retroelement-derived transcripts for the evolution of a pathogen virulence effector.

scholarly journals ROP INTERACTIVE PARTNER b interacts with RACB and supports fungal penetration into barley epidermal cells

2019 ◽  
Author(s):  
Christopher McCollum ◽  
Stefan Engelhardt ◽  
Lukas Weiss ◽  
Ralph Hückelhoven
Keyword(s):  
Plasma Membrane ◽  
Powdery Mildew ◽  
Coiled Coil ◽  
Cell Polarization ◽  
Epidermal Cells ◽  
In Planta ◽  
Powdery Mildew Fungus ◽  
Susceptibility Factor ◽  
Polar Cell ◽  
Barley Powdery Mildew

AbstractRHO of Plants (ROP) G-proteins are key components of cell polarization processes in plant development. The barley (Hordeum vulgare) ROP protein RACB, is a susceptibility factor in the interaction of barley with the barley powdery mildew fungus Blumeria graminis f.sp. hordei (Bgh). RACB also drives polar cell development, and this function might be coopted during formation of fungal haustoria in barley epidermal cells. In order to understand RACB signaling during the interaction of barley with Bgh, we searched for potential downstream interactors of RACB. Here, we show that ROP INTERACTIVE PARTNER b (RIPb, synonym: INTERACTOR OF CONSTITUTIVE ACTIVE ROP b; ICRb) directly interacts with RACB in yeast and in planta. Over-expression of RIPb supports susceptibility of barley to Bgh. RIPb further interacts with itself at microtubules. However, the interaction with activated RACB takes place at the plasma membrane. Both, RIPb and RACB are recruited to the site of fungal attack around the neck of developing haustoria suggesting locally enhanced ROP activity. We further assigned different functions to different domains of the RIPb protein. The N-terminal coiled-coil CC1 domain is required for microtubule localization, while the C-terminal coiled-coil CC2 domain is sufficient to interact with RACB and to fulfill a function in susceptibility at the plasma membrane. Hence, RIPb appears to be localized at microtubules and is then recruited by activated RACB for a function at the plasma membrane during formation of the haustorial complex.One Sentence summaryRIPb acts downstream of the powdery mildew susceptibility factor RACB of barley and influences susceptibility

scholarly journals Disruption of barley immunity to powdery mildew by an in-frame Lys-Leu deletion in the essential protein SGT1

Genetics ◽  
2020 ◽  
Vol 217 (2) ◽  
Author(s):  
Antony V E Chapman ◽  
Matthew Hunt ◽  
Priyanka Surana ◽  
Valeria Velásquez-Zapata ◽  
Weihui Xu ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Fungal Pathogens ◽  
Novel Mutation ◽  
Exome Capture ◽  
Resistance Locus ◽  
Hordeum Vulgare L ◽  
Powdery Mildew Fungus ◽  
Pathogen Effectors ◽  
Cell Processes ◽  
Disease Resistances

Abstract Barley (Hordeum vulgare L.) Mla (Mildew resistance locus a) and its nucleotide-binding, leucine-rich-repeat receptor (NLR) orthologs protect many cereal crops from diseases caused by fungal pathogens. However, large segments of the Mla pathway and its mechanisms remain unknown. To further characterize the molecular interactions required for NLR-based immunity, we used fast-neutron mutagenesis to screen for plants compromised in MLA-mediated response to the powdery mildew fungus, Blumeria graminis f. sp. hordei. One variant, m11526, contained a novel mutation, designated rar3 (required for Mla6 resistance3), that abolishes race-specific resistance conditioned by the Mla6, Mla7, and Mla12 alleles, but does not compromise immunity mediated by Mla1, Mla9, Mla10, and Mla13. This is analogous to, but unique from, the differential requirement of Mla alleles for the co-chaperone Rar1 (required for Mla12 resistance1). We used bulked-segregant-exome capture and fine mapping to delineate the causal mutation to an in-frame Lys-Leu deletion within the SGS domain of SGT1 (Suppressor of G-two allele of Skp1, Sgt1ΔKL308–309), the structural region that interacts with MLA proteins. In nature, mutations to Sgt1 usually cause lethal phenotypes, but here we pinpoint a unique modification that delineates its requirement for some disease resistances, while unaffecting others as well as normal cell processes. Moreover, the data indicate that the requirement of SGT1 for resistance signaling by NLRs can be delimited to single sites on the protein. Further study could distinguish the regions by which pathogen effectors and host proteins interact with SGT1, facilitating precise editing of effector incompatible variants.

scholarly journals Powdery Mildew Fungus on Cucurbits in the Transvaal Province of South Africa

Nature ◽  
1966 ◽  
Vol 209 (5026) ◽  
pp. 938-938 ◽  
Author(s):  
G. J. M. A. GORTER
Keyword(s):  
South Africa ◽  
Powdery Mildew ◽  
Powdery Mildew Fungus

scholarly journals Erysiphe trifolii Causing Powdery Mildew of Lentil (Lens culinaris)

Plant Disease ◽  
2009 ◽  
Vol 93 (8) ◽  
pp. 797-803 ◽  
Author(s):  
Renuka N. Attanayake ◽  
Dean A. Glawe ◽  
Frank M. Dugan ◽  
Weidong Chen
Keyword(s):  
Powdery Mildew ◽  
Pacific Northwest ◽  
The United States ◽  
Morphological Characters ◽  
Grain Legumes ◽  
Its Sequences ◽  
Powdery Mildew Fungus ◽  
The Pacific ◽  
Soybean Genotypes ◽  
Erysiphe Trifolii

The taxonomy of the powdery mildew fungus infecting lentil in the Pacific Northwest (PNW) of the United States was investigated on the basis of morphology and rDNA internal transcribed spacer (ITS) sequences. Anamorphic characters were in close agreement with descriptions of Erysiphe trifolii. However, teleomorphs formed chasmothecial appendages with highly branched apices, whereas E. trifolii has been described as producing flexuous or sometimes loosely branched appendages. Branched appendages have been described in Erysiphe diffusa, a fungus reported from species of Lens, Glycine, and Sophora, raising the possibility that the PNW fungus could be E. diffusa. Examination of morphological characters of an authentic specimen of E. trifolii from Austria determined that it included chasmothecial appendages resembling those seen in PNW specimens. Furthermore, ITS sequences from five powdery mildew samples collected from lentils in PNW greenhouses and fields from 2006 to 2008 were identical to one another, and exhibited higher similarity to sequences of E. trifolii (99%) than to those of any other Erysiphe spp. available in GenBank. Parsimony analysis grouped the lentil powdery mildew into a clade with Erysiphe baeumleri, E. trifolii, and E. trifolii–like Oidium sp., but indicated a more distant relationship to E. diffusa. In greenhouse inoculation studies, the lentil powdery mildew fungus did not infect soybean genotypes known to be susceptible to E. diffusa. The pathogenicity of E. trifolii on lentil was confirmed using modified Koch's postulates. This is the first report of E. trifolii infecting lentil. E. diffusa and E. trifolii have different host ranges, so the discovery of E. trifolii on lentil has implications both for determining species of powdery mildews on cool-season grain legumes, and in disease management.

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