scholarly journals Host-Induced Gene Silencing in Barley Powdery Mildew Reveals a Class of Ribonuclease-Like Effectors

2013 ◽  
Vol 26 (6) ◽  
pp. 633-642 ◽  
Author(s):  
Clara Pliego ◽  
Daniela Nowara ◽  
Giulia Bonciani ◽  
Dana M. Gheorghe ◽  
Ruo Xu ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Gene Silencing ◽  
Transcript Abundance ◽  
Powdery Mildew Fungus ◽  
Host Cell Death ◽  
Barley Powdery Mildew ◽  
Biotrophic Pathogens ◽  
Powdery Mildew Fungi ◽  
Bona Fide ◽  
Do So

Obligate biotrophic pathogens of plants must circumvent or counteract defenses to guarantee accommodation inside the host. To do so, they secrete a variety of effectors that regulate host immunity and facilitate the establishment of pathogen feeding structures called haustoria. The barley powdery mildew fungus Blumeria graminis f. sp. hordei produces a large number of proteins predicted to be secreted from haustoria. Fifty of these Blumeria effector candidates (BEC) were screened by host-induced gene silencing (HIGS), and eight were identified that contribute to infection. One shows similarity to β-1,3 glucosyltransferases, one to metallo-proteases, and two to microbial secreted ribonucleases; the remainder have no similarity to proteins of known function. Transcript abundance of all eight BEC increases dramatically in the early stages of infection and establishment of haustoria, consistent with a role in that process. Complementation analysis using silencing-insensitive synthetic cDNAs demonstrated that the ribonuclease-like BEC 1011 and 1054 are bona fide effectors that function within the plant cell. BEC1011 specifically interferes with pathogen-induced host cell death. Both are part of a gene superfamily unique to the powdery mildew fungi. Structural modeling was consistent, with BEC1054 adopting a ribonuclease-like fold, a scaffold not previously associated with effector function.

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.

Studies of the powdery-mildew fungus, Leveillula taurica, on green pepper. II. Light and electron microscopic observation of the infection process

1979 ◽  
Vol 57 (22) ◽  
pp. 2501-2508 ◽  
Author(s):  
Hitoshi Kunoh ◽  
Mitsuru Kohno ◽  
Sadayoshi Tashiro ◽  
Hiroshi Ishizaki
Keyword(s):  
Powdery Mildew ◽  
Light And Electron Microscopy ◽  
Host Cells ◽  
Outer Cell ◽  
Lipid Bodies ◽  
Powdery Mildew Fungus ◽  
Green Pepper ◽  
Ultrastructural Studies ◽  
Leveillula Taurica ◽  
Powdery Mildew Fungi

Almost all ultrastructural studies of powdery-mildew fungi have been focused on the epiparasitic fungi. In this paper, one of the endoparasitic powdery-mildew fungi, Leveillula taurica (Lev.) Arn., on green pepper (Capsicum annuum L. var. angulosum Mill.) leaves was investigated by light and electron microscopy. Most germinated conidia formed a lobed adhesion body (similar to the appressorium in morphology but different in function) before stomatal invasion. The track of the adhesion body on the leaf epidermis was depressed, and no cuticular perforations were observed in it. After stomatal invasion, infection hyphae grew extensively into the intercellular spaces of the leaves and formed haustoria in the spongy- and palisade-parenchyma cells. The haustorium was flask shaped with a neck arising from the intercellular hypha. The overall profiles of the haustorium resembled those of epiphytic powdery-mildew fungi of other authors; the haustorium was composed of a nucleate central body and many anucleate lobes, and the entire structure was bounded by an extrahaustorial membrane. Papillae consisting of three distinct regions formed against the outer cell walls at the site of penetration. The most obvious alteration in infected host cells was a marked increase in the number of large lipid bodies. Lipid bodies increased in number with time after haustorial formation. They appeared first in the host cytoplasm near the extrahaustorial membrane, then in the extrahaustorial matrix and haustorial body.

Impact of proquinazid on appressorial development of the barley powdery mildew fungus Blumeria graminis f.sp hordei

2009 ◽  
Vol 94 (2-3) ◽  
pp. 127-132 ◽  
Author(s):  
Sally R. Gilbert ◽  
Hans J. Cools ◽  
Bart A. Fraaije ◽  
Andy M. Bailey ◽  
John A. Lucas
Keyword(s):  
Powdery Mildew ◽  
Blumeria Graminis ◽  
Powdery Mildew Fungus ◽  
Barley Powdery Mildew

scholarly journals The partial duplication of an E3-ligase gene in Triticeae species mediates resistance to powdery mildew fungi

2017 ◽  
Author(s):  
Jeyaraman Rajaraman ◽  
Dimitar Douchkov ◽  
Stefanie Lück ◽  
Götz Hensel ◽  
Daniela Nowara ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
E3 Ligase ◽  
Defense Responses ◽  
Duplication Event ◽  
Stable Gene ◽  
Cellular Functions ◽  
Powdery Mildew Fungus ◽  
Crop Species ◽  
Powdery Mildew Fungi ◽  
Plant Pathogen Interactions

ABSTRACTIn plant-pathogen interactions, components of the plant ubiquitination machinery are preferred targets of pathogen-encoded effectors suppressing defense responses or co-opting host cellular functions for accommodation. Here, we employed transient and stable gene silencing-and over-expression systems in Hordeum vulgare (barley) to study the function of HvARM1 (for H. vulgare Armadillo 1), a partial gene duplicate of the U-box/armadillo-repeat E3 ligase HvPUB15 (for H. vulgare Plant U-Box 15). The partial ARM1 gene was derived from an ancient gene-duplication event in a common ancestor of the Triticeae tribe of grasses comprising the major crop species H. vulgare, Triticum aestivum and Secale cereale. The barley gene HvARM1 contributed to quantitative host as well as nonhost resistance to the biotrophic powdery mildew fungus Blumeria graminis, and allelic variants were found to be associated with powdery mildew-disease severity. Both HvPUB15 and HvARM1 proteins interacted in yeast and plant cells with the susceptibility-related, plastid-localized barley homologs of THF1 (for Thylakoid formation 1) and of ClpS1 (for Clp-protease adaptor S1) of Arabidopsis thaliana. The results suggest a neo-functionalization HvARM1 to increase resistance against powdery mildew and provide a link to plastid function in susceptibility to biotrophic pathogen attack.

scholarly journals The isoelectric point of proteins influences their translocation to the extrahaustorial matrix of the barley powdery mildew fungus

2019 ◽  
Vol 21 (12) ◽  
Author(s):  
Lara Smigielski ◽  
Geziel B. Aguilar ◽  
Mark Kwaaitaal ◽  
Wen‐Jing Zhang ◽  
Hans Thordal‐Christensen
Keyword(s):  
Powdery Mildew ◽  
Isoelectric Point ◽  
Powdery Mildew Fungus ◽  
Barley Powdery Mildew ◽  
Extrahaustorial Matrix

Antifungal Activity of Zanthoxylium schinifolium Against Fusarium graminearum, a Barley Powdery Mildew Fungus.

2008 ◽  
Vol 18 (7) ◽  
pp. 974-979 ◽  
Author(s):  
Byum-Soo Kim ◽  
Han-Su Jang ◽  
Chung-Sig Choi ◽  
Jong-Sik Kim ◽  
Gi-Seok Kwon ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Powdery Mildew ◽  
Fusarium Graminearum ◽  
Powdery Mildew Fungus ◽  
Barley Powdery Mildew

scholarly journals The Parauncinula polyspora Draft Genome Provides Insights into Patterns of Gene Erosion and Genome Expansion in Powdery Mildew Fungi

mBio ◽  
2019 ◽  
Vol 10 (5) ◽  
Author(s):  
Lamprinos Frantzeskakis ◽  
Márk Z. Németh ◽  
Mirna Barsoum ◽  
Stefan Kusch ◽  
Levente Kiss ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Defense Mechanism ◽  
Repetitive Sequences ◽  
Draft Genome ◽  
Model Systems ◽  
Powdery Mildew Fungus ◽  
Evolutionary Trajectory ◽  
Reproduction Strategy ◽  
Powdery Mildew Fungi ◽  
Fungal Genes

ABSTRACT Due to their comparatively small genome size and short generation time, fungi are exquisite model systems to study eukaryotic genome evolution. Powdery mildew fungi present an exceptional case because of their strict host dependency (termed obligate biotrophy) and the atypical size of their genomes (>100 Mb). This size expansion is largely due to the pervasiveness of transposable elements on 70% of the genome and is associated with the loss of multiple conserved ascomycete genes required for a free-living lifestyle. To date, little is known about the mechanisms that drove these changes, and information on ancestral powdery mildew genomes is lacking. We report genome analysis of the early-diverged and exclusively sexually reproducing powdery mildew fungus Parauncinula polyspora, which we performed on the basis of a natural leaf epiphytic metapopulation sample. In contrast to other sequenced species of this taxonomic group, the assembled P. polyspora draft genome is surprisingly small (<30 Mb), has a higher content of conserved ascomycete genes, and is sparsely equipped with transposons (<10%), despite the conserved absence of a common defense mechanism involved in constraining repetitive elements. We speculate that transposable element spread might have been limited by this pathogen’s unique reproduction strategy and host features and further hypothesize that the loss of conserved ascomycete genes may promote the evolutionary isolation and host niche specialization of powdery mildew fungi. Limitations associated with this evolutionary trajectory might have been in part counteracted by the evolution of plastic, transposon-rich genomes and/or the expansion of gene families encoding secreted virulence proteins. IMPORTANCE Powdery mildew fungi are widespread and agronomically relevant phytopathogens causing major yield losses. Their genomes have disproportionately large numbers of mobile genetic elements, and they have experienced a significant loss of highly conserved fungal genes. In order to learn more about the evolutionary history of this fungal group, we explored the genome of an Asian oak tree pathogen, Parauncinula polyspora, a species that diverged early during evolution from the remaining powdery mildew fungi. We found that the P. polyspora draft genome is comparatively compact, has a low number of protein-coding genes, and, despite the absence of a dedicated genome defense system, lacks the massive proliferation of repetitive sequences. Based on these findings, we infer an evolutionary trajectory that shaped the genomes of powdery mildew fungi.

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