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 Transgenic Suppression of Cell Death Limits Penetration Success of the Soybean Rust Fungus Phakopsora pachyrhizi into Epidermal Cells of Barley

2009 ◽  
Vol 99 (3) ◽  
pp. 220-226 ◽  
Author(s):  
Caroline Hoefle ◽  
Marco Loehrer ◽  
Ulrich Schaffrath ◽  
Markus Frank ◽  
Holger Schultheiss ◽  
...  
Keyword(s):  
Cell Death ◽  
Epidermal Cell ◽  
Plant Cell Wall ◽  
Rust Fungus ◽  
Mesophyll Cell ◽  
Epidermal Cells ◽  
Plant Diseases ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Hypersensitive Cell Death

The basidiomycete Phakopsora pachyrhizi (P. pachyrhizi) causes Asian soybean rust, one of the most devastating plant diseases on soybean. When inoculated on the nonhost barley P. pachyrhizi caused only very small necrotic spots, typical for an incompatible interaction, which involves a hypersensitive cell death reaction. A microscopic inspection of the interaction of barley with P. pachyrhizi revealed that the fungus germinated on barley and formed functional appressoria on epidermal cells. The fungus attempted to directly penetrate through periclinal cell walls but often failed, arrested in plant cell wall appositions that stained positively for callose. Penetration resistance depends on intact ROR1(REQUIRED FOR mlo-SPECIFIED RESISTANCE 1) and ROR2 genes of barley. If the fungus succeeded in penetration, epidermal cell death took place. Dead epidermal cells did not generally restrict fungal development but allowed for mesophyll invasion, which was followed by mesophyll cell death and fungal arrest. Transient or stable over expression of the barley cell death suppressor BAX inhibitor-1 reduced both epidermal cell death and fungal penetration success. Data suggest that P. pachyrhizi provokes a programmed cell death facilitating fungal entry into epidermal cells of barley.

scholarly journals Tissue Dependence and Differential Cordycepin Sensitivity of Race-Specific Resistance Responses in the Barley—Powdery Mildew Interaction

1997 ◽  
Vol 10 (7) ◽  
pp. 830-839 ◽  
Author(s):  
Ruth Schiffer ◽  
Regina Görg ◽  
Birgit Jarosch ◽  
Uli Beckhove ◽  
Gregor Bahrenberg ◽  
...  
Keyword(s):  
Cell Death ◽  
Powdery Mildew ◽  
Host Cell ◽  
Specific Resistance ◽  
Leaf Tissue ◽  
Primary Leaf ◽  
Hypersensitive Cell Death ◽  
Fungal Development ◽  
Interaction Sites ◽  
Host Cell Death

Epidermal cell monolayers prepared from partially dissected barley (Hordeum vulgare) coleoptiles were used for in vivo analysis of race-specific resistance to powdery mildew (Erysiphe graminis f. sp. hordei) specified by host genes Mla-1, Mla-12, and Mlg. Complete resistance governed by each of these genes is closely associated with hypersensitive cell death (hypersensitive response, HR) in primary leaf tissue. In contrast, Mla-12 coleoptile tissue reveals a fully compatible, Mla-1 coleoptile tissue a partially compatible, and Mlg coleoptile tissue an incompatible interaction upon challenge with pathogen races carrying corresponding avirulence functions. Quantitative recording of single plant-fungus interaction sites showed arrest of fungal development in papillae on Mlg coleoptiles. On Mla-1 and Mla-12 coleoptiles, attacked cells become predominantly penetrated by the fungus. Approximately one third of penetrated cells on Mla-1 coleoptiles subsequently undergo an HR. These sites reveal no further fungal development. Both Mlg and Mla-12 coleoptiles fail to mount an HR. The effect of cordycepin (3′-deoxyadenosine), an inhibitor of mRNA synthesis, was studied in planta on primary leaf tissue of Mla-12 and Mlg genotypes. Host cell death triggered by either gene is reduced to background levels observed in the near-isogenic compatible interaction and exhibits the same dose-dependent cordycepin sensitivity. Inhibition of Mlg-triggered, single-cell HR is not accompanied by release of fungal growth arrest, indicating cordycepin insensitivity of a papillae-associated resistance component. The data suggest that host cell death is a requisite component for expression of Mla-type but not Mlg-type resistance.

scholarly journals BAX INHIBITOR-1 Is Required for Full Susceptibility of Barley to Powdery Mildew

2010 ◽  
Vol 23 (9) ◽  
pp. 1217-1227 ◽  
Author(s):  
Ruth Eichmann ◽  
Melanie Bischof ◽  
Corina Weis ◽  
Jane Shaw ◽  
Christophe Lacomme ◽  
...  
Keyword(s):  
Cell Death ◽  
Powdery Mildew ◽  
Gene Silencing ◽  
Defense Responses ◽  
Negative Control ◽  
Cellular Level ◽  
Virus Induced Gene Silencing ◽  
Powdery Mildew Fungus ◽  
Basal Resistance ◽  
Enhanced Resistance

BAX INHIBITOR-1 (BI-1) is one of the few proteins known to have cross-kingdom conserved functions in negative control of programmed cell death. Additionally, barley BI-1 (HvBI-1) suppresses defense responses and basal resistance to the powdery mildew fungus Blumeria graminis f. sp. hordei and enhances resistance to cell death–provoking fungi when overexpressed in barley. Downregulation of HvBI-1 by transient-induced gene silencing or virus-induced gene silencing limited susceptibility to B. graminis f. sp. hordei, suggesting that HvBI-1 is a susceptibility factor toward powdery mildew. Transient silencing of BI-1 did not limit supersusceptibility induced by overexpression of MLO. Transgenic barley plants harboring an HvBI-1 RNA interference (RNAi) construct displayed lower levels of HvBI-1 transcripts and were less susceptible to powdery mildew than wild-type plants. At the cellular level, HvBI-1 RNAi plants had enhanced resistance to penetration by B. graminis f. sp. hordei. These data support a function of BI-1 in modulating cell-wall-associated defense and in establishing full compatibility of B. graminis f. sp. hordei with barley.

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

Heat-induced resistance in barley to the powdery mildew fungus Erysiphe graminis f.sp. hordei

1995 ◽  
Vol 47 (1) ◽  
pp. 51-66 ◽  
Author(s):  
Patrick Schweizer ◽  
Laurence Vallélian-Bindschedler ◽  
Egon Mösinger
Keyword(s):  
Powdery Mildew ◽  
Induced Resistance ◽  
Erysiphe Graminis ◽  
Powdery Mildew Fungus

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.

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