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 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.

scholarly journals A Candidate Secreted Effector Protein of Rubber Tree Powdery Mildew Fungus Contributes to Infection by Regulating Plant ABA Biosynthesis

2020 ◽  
Vol 11 ◽  
Author(s):  
Xiao Li ◽  
Yuhan Liu ◽  
Qiguang He ◽  
Sipeng Li ◽  
Wenbo Liu ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Natural Rubber ◽  
Rubber Tree ◽  
Primary Source ◽  
Defense Responses ◽  
Effector Proteins ◽  
Powdery Mildew Fungus ◽  
Successful Infection ◽  
Wide Range ◽  
Aba Biosynthesis

Powdery mildew infects a wide range of crops and economic plants, causing substantial losses. Rubber trees (Hevea brasiliensis) are the primary source of natural rubber, and powdery mildew infection causes significant losses to natural rubber yields. How the causal agent, Erysiphe quercicola, establishes successful infection in rubber trees is largely unknown. Previously, 133 candidate secreted effector proteins (CSEPs) were identified in powdery mildew fungus. In this study, we characterize a CSEP named EqCSEP01276 for its function in suppressing host plant defense responses. We show that EqCSEP01276 is a secreted protein and is able to disturb the localization of 9-cis-epoxycarotenoid dioxygenase 5 (HbNCED5), a key enzyme in abscisic acid (ABA) biosynthesis in plant cell chloroplasts of H. brasiliensis. We also show that this effector inhibits ABA biosynthesis, and that in H. brasiliensis ABA is a positive regulator of the plant immune response against powdery mildew. Our study reveals a strategy by which powdery mildew fungus manipulates plant ABA-mediated defense for a successful infection.

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 Resistance to rust and powdery mildew in Lathyrus crops

2014 ◽  
Vol 50 (No. 2) ◽  
pp. 116-122 ◽  
Author(s):  
M.C. Vaz Patto ◽  
D. Rubiales
Keyword(s):  
Powdery Mildew ◽  
Resistance Mechanisms ◽  
Grain Legumes ◽  
High Potential ◽  
Lathyrus Sativus ◽  
Crop Species ◽  
Fodder Crops ◽  
Powdery Mildew Fungi

Several Lathyrus species, particularly Lathyrus sativus and L. cicera, have a high potential both as food and fodder crops. Rust and powdery mildew fungi are among the most important pathogens of major grain legumes including Lathyrus species. We review and critically discuss available knowledge of the existence of resistance and the underlying resistance mechanisms against rust and powdery mildew in the L. sativus and L. cicera crop species.

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.

scholarly journals Infection of papaya (Carica papaya) by four powdery mildew fungi

2021 ◽  
Vol 60 (1) ◽  
pp. 37-49
Author(s):  
Diána SERESS ◽  
Gábor M. KOVÁCS ◽  
Orsolya MOLNÁR ◽  
Márk Z. NÉMETH
Keyword(s):  
Powdery Mildew ◽  
New Record ◽  
Species Complex ◽  
Carica Papaya ◽  
Phylogenetic Analyses ◽  
Molecular Taxonomy ◽  
Podosphaera Xanthii ◽  
Powdery Mildew Fungus ◽  
Molecular Phylogenetic ◽  
Powdery Mildew Fungi

Papaya (Carica papaya L.) is an important fruit crop in many tropical and subtropical countries. Powdery mildew commonly affects this host, causing premature leaf loss, reduced yields and poor fruit quality. At least fifteen different fungi have been identified as the causal agents of papaya powdery mildew. Powdery mildew symptoms were detected on potted papaya plants growing in two locations in Hungary. This study aimed to identify the causal agents. Morphology of powdery mildew samples was examined, and sequences of two loci were used for molecular taxonomic identifications. Only anamophs were detected in all samples, and four morphological types were distinguished. Most samples had Pseudoidium anamorphs, while some were of the Fibroidium anamorph. Based on morphology and molecular taxonomy, the Fibroidium anamorph  was identified as Podosphaera xanthii. The Pseudoidium anamorphs corresponded to three different Erysiphe species: E. cruciferarum, E. necator and an unidentified Erysiphe sp., for which molecular phylogenetic analyses showed it belonged to an unresolved species complex of E. malvae, E. heraclei and E. betae. Infectivity of P. xanthii and E. necator on papaya was verified with cross inoculations. A review of previous records of powdery mildew fungi infecting papaya is also provided. Podosphaera xanthii was known to infect, and E. cruciferarum was suspected to infect Carica papaya, while E. necator was recorded on this host only once previously. No powdery mildew fungus belonging to the E. malvae/E. heraclei/E. betae species complex is known to infect papaya or any other plants in the Caricaceae, so the unidentified Erysiphe sp. is a new record on papaya and the Caricaceae. This study indicates host range expansion of this powdery mildew fungus onto papaya.

scholarly journals Barley Rom1 Reveals a Potential Link Between Race-Specific and Nonhost Resistance Responses to Powdery Mildew Fungi

2005 ◽  
Vol 18 (4) ◽  
pp. 291-299 ◽  
Author(s):  
Andreas Freialdenhoven ◽  
James Orme ◽  
Thomas Lahaye ◽  
Paul Schulze-Lefert
Keyword(s):  
Cell Death ◽  
Powdery Mildew ◽  
Oxidative Burst ◽  
Defense Responses ◽  
Avirulence Gene ◽  
Resistance Response ◽  
Cell Death Response ◽  
Potential Link ◽  
Powdery Mildew Fungi ◽  
Barley Resistance

The Rar1 gene, identified in the context of race-specific powdery mildew resistance mediated by the Hordeum vulgare (barley) resistance (R) gene Mla12, is required for the function of many R-mediated responses in monoand dicotyledonous plant species. Mla resistance is associated with an oxidative burst and a subsequent cell death reaction of attacked cells. Rar1 mutants are impaired in these responses and, to identify genetic elements which negatively regulate the Mla12-triggered response, we have screened mutagenized Mla12 rar1 mutant populations for restoration of the resistance response. Here we describe the restoration of Mla12-specified resistance (rom1) mutant that restores features of disease resistance to a Blumeria graminis f. sp. hordei isolate expressing the avirulence gene AvrMla12 and retains susceptibility to an isolate lacking AvrMla12. Histochemical analyses show that, in rom1 mutant plants, a whole-cell oxidative burst and cell death response in attacked epidermal cells is restored in the incompatible interaction. Defense responses against tested inappropriate powdery mildews, B. graminis f. sp. tritici and Golovinomyces orontii, were diminished in rar1 mutant plants and enhanced in rom1 mutant plants relative to the wild type. These findings indicate antagonistic activities of Rar1 and Rom1 and reveal their contribution to nonhost and race-specific resistance responses.

Initial events in the colonisation of tomatoes by Oidium lycopersici, a distinct powdery mildew fungus of Lycopersicon species

2000 ◽  
Vol 78 (10) ◽  
pp. 1361-1366 ◽  
Author(s):  
Hannah E Jones ◽  
John M Whipps ◽  
Barry J Thomas ◽  
Tim LW Carver ◽  
Sarah J Gurr
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Powdery Mildew ◽  
Intergenic Spacer ◽  
Powdery Mildew Fungus ◽  
Subsequent Formation ◽  
Powdery Mildew Fungi ◽  
Tomato Powdery Mildew ◽  
Oidium Lycopersici ◽  
Scanning Electron

The rDNA intergenic spacer sequence of Oidium lycopersici (ana.; Cooke & Massee 1888, emend. Noordeloos and Loerakker 1989, emend. Mieslerova and Lebeda 1999) was determined and compared with the sequences of other powdery mildews. This pathogen was shown to be distinct from other powdery mildew fungi found on tomato, but it exhibited a close similarity to Erysiphe aquilegiae var. ranunculi. The initial events involved in the germination of conidia and subsequent formation of the appressorium in the newly described powdery mildew of tomato, O. lycopersici, were studied by light and scanning electron microscopy. Scanning electron microscopy revealed the conidial coat to be smooth to slightly rugose and the appressoria to be multilobed and attached to the host by a mucilaginous pad of extracellular material.Key words: Oidium lycopersici, tomato powdery mildew, ITS, life cycle, light microscopy, electron microscopy.

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