scholarly journals Quantitative and Temporal Definition of the Mla Transcriptional Regulon During Barley–Powdery Mildew Interactions

2011 ◽  
Vol 24 (6) ◽  
pp. 694-705 ◽  
Author(s):  
Matthew J. Moscou ◽  
Nick Lauter ◽  
Rico A. Caldo ◽  
Dan Nettleton ◽  
Roger P. Wise
Keyword(s):  
Powdery Mildew ◽  
Expression Profiles ◽  
Coiled Coil ◽  
Transcriptional Response ◽  
Hypersensitive Reaction ◽  
Resistance Locus ◽  
Loss Of Function ◽  
Transcriptional Targets ◽  
Downstream Signaling ◽  
Powdery Mildew Pathogen

Barley Mildew resistance locus a (Mla) is a major determinant of immunity to the powdery mildew pathogen, Blumeria graminis f. sp. hordei. Alleles of Mla encode cytoplasmic- and membrane-localized coiled-coil, nucleotide binding site, leucine-rich repeat proteins that mediate resistance when complementary avirulence effectors (AVRa) are present in the pathogen. Presence of an appropriate AVRa protein triggers nuclear relocalization of MLA, in which MLA binds repressing host transcription factors. Timecourse expression profiles of plants harboring Mla1, Mla6, and Mla12 wild-type alleles versus paired loss-of-function mutants were compared to discover conserved transcriptional targets of MLA and downstream signaling cascades. Pathogen-dependent gene expression was equivalent or stronger in susceptible plants at 20 h after inoculation (HAI) and was attenuated at later timepoints, whereas resistant plants exhibited a time-dependent strengthening of the transcriptional response, increasing in both fold change and the number of genes differentially expressed. Deregulation at 20 HAI implicated 16 HAI as a crucial point in determining the future trajectory of this interaction and was interrogated by quantitative analysis. In total, 28 potential transcriptional targets of the MLA regulon were identified. These candidate targets possess a diverse set of predicted functions, suggesting that multiple pathways are required to mediate the hypersensitive reaction.

scholarly journals Expression Pattern Analysis of Four Mlo Genes from Rose

2015 ◽  
Vol 140 (4) ◽  
pp. 333-338 ◽  
Author(s):  
Xianqin Qiu ◽  
Hongying Jian ◽  
Qigang Wang ◽  
Kaixue Tang ◽  
Manzhu Bao
Keyword(s):  
Powdery Mildew ◽  
Quantitative Polymerase Chain Reaction ◽  
Expression Patterns ◽  
Early Time ◽  
Resistance Locus ◽  
Loss Of Function ◽  
Powdery Mildew Fungus ◽  
Mildew Resistance ◽  
Powdery Mildew Pathogen ◽  
External Stimuli

Rose (Rosa hybrida) is one of the most economically important ornamentals worldwide. Powdery mildew (Podosphaera pannosa) is a major disease in cut and potted roses. In dicots such as arabidopsis (Arabidopsis thaliana), pea (Pisum sativum), and tomato (Solanum lycopersicum), loss-of-function mutations in mildew resistance locus o (Mlo) genes confer high levels of broad-spectrum resistance to powdery mildew. Here, we present spatiotemporal expression patterns of four Mlo genes from R. hybrida based on real-time fluorescence quantitative polymerase chain reaction (qPCR). Phylogenetically closely related R. hybrida mildew resistance locus o (RhMLO) genes showed similar or overlapping tissue specificity and analogous responsiveness to external stimuli. RhMLO1 and RhMLO2 transcriptional levels were upregulated more than 2-fold by external stimuli, especially by inoculation with powdery mildew fungus P. pannosa at early time points. This phenomenon was not found for RhMLO3 or RhMLO4. The results indicated that RhMLO1 and RhMLO2 might play important roles in rose–powdery mildew pathogen interactions. Our findings may provide useful information for the study of mechanisms of powdery mildew susceptibility in rose.

scholarly journals Diversity at the Mla Powdery Mildew Resistance Locus from Cultivated Barley Reveals Sites of Positive Selection

2010 ◽  
Vol 23 (4) ◽  
pp. 497-509 ◽  
Author(s):  
Sabine Seeholzer ◽  
Takashi Tsuchimatsu ◽  
Tina Jordan ◽  
Stéphane Bieri ◽  
Simone Pajonk ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Positive Selection ◽  
Transient Gene Expression ◽  
Coiled Coil ◽  
Resistance Locus ◽  
Powdery Mildew Fungus ◽  
Genetic Studies ◽  
Mla Locus ◽  
Or Gene ◽  
Positively Selected Sites

The Mla locus in barley (Hordeum vulgare) conditions isolate-specific immunity to the powdery mildew fungus (Blumeria graminis f. sp. hordei) and encodes intracellular coiled-coil (CC) domain, nucleotide-binding (NB) site, and leucine-rich repeat (LRR)-containing receptor proteins. Over the last decades, genetic studies in breeding material have identified a large number of functional resistance genes at the Mla locus. To study the structural and functional diversity of this locus at the molecular level, we isolated 23 candidate MLA cDNAs from barley accessions that were previously shown by genetic studies to harbor different Mla resistance specificities. Resistance activity was detected for 13 candidate MLA cDNAs in a transient gene-expression assay. Sequence alignment of the deduced MLA proteins improved secondary structure predictions, revealing four additional, previously overlooked LRR. Analysis of nucleotide diversity of the candidate and validated MLA cDNAs revealed 34 sites of positive selection. Recombination or gene conversion events were frequent in the first half of the gene but positive selection was also found when this region was excluded. The positively selected sites are all, except two, located in the LRR domain and cluster in predicted solvent-exposed residues of the repeats 7 to 15 and adjacent turns on the concave side of the predicted solenoid protein structure. This domain-restricted pattern of positively selected sites, together with the length conservation of individual LRR, suggests direct binding of effectors to MLA receptors.

scholarly journals Loss-of-Function Mutations in Chitin Responsive Genes Show Increased Susceptibility to the Powdery Mildew Pathogen Erysiphe cichoracearum

2005 ◽  
Vol 138 (2) ◽  
pp. 1027-1036 ◽  
Author(s):  
Katrina Ramonell ◽  
Marta Berrocal-Lobo ◽  
Serry Koh ◽  
Jinrong Wan ◽  
Herb Edwards ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Loss Of Function ◽  
Erysiphe Cichoracearum ◽  
Powdery Mildew Pathogen ◽  
Increased Susceptibility

scholarly journals A fungal plant pathogen overcomes conserved broad-spectrum disease resistance by rapid gene loss

2021 ◽  
Author(s):  
Stefan Kusch ◽  
Lamprinos Frantzeskakis ◽  
Birthe D. Lassen ◽  
Florian Kümmel ◽  
Lina Pesch ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Broad Spectrum ◽  
Plant Pathogen ◽  
Experimental Evolution ◽  
Loss Of Function ◽  
Adaptive Mutations ◽  
Broad Spectrum Resistance ◽  
Dynamic Genome ◽  
Powdery Mildew Fungi ◽  
Powdery Mildew Pathogen

Hosts and pathogens typically engage in an evolutionary arms race. This also applies to phytopathogenic powdery mildew fungi, which can rapidly overcome plant resistance and perform host jumps. Using experimental evolution, we show that the powdery mildew pathogen Blumeria graminis f.sp. hordei is capable of breaking the agriculturally important broad-spectrum resistance conditioned by barley loss-of-function mlo mutants. Partial mlo virulence is associated with a distinctive pattern of adaptive mutations, including small-sized (8-40 kb) deletions, one of which likely affects spore morphology. The detected mutational spectrum comprises the same loci in at least two independent mlo-virulent isolates, indicating convergent multigenic evolution. This work highlights the dynamic genome evolution of an obligate biotrophic plant pathogen with a transposon-enriched genome.

scholarly journals mlo-Based Resistance: An Apparently Universal “Weapon” to Defeat Powdery Mildew Disease

2017 ◽  
Vol 30 (3) ◽  
pp. 179-189 ◽  
Author(s):  
Stefan Kusch ◽  
Ralph Panstruga
Keyword(s):  
Powdery Mildew ◽  
Plant Species ◽  
Resistance Locus ◽  
Loss Of Function ◽  
Knock Out ◽  
Barley Landrace ◽  
Powdery Mildew Disease ◽  
Powdery Mildew Fungi ◽  
Induced Mutagenesis ◽  
Natural Mutation

Loss-of-function mutations of one or more of the appropriate Mildew resistance locus o (Mlo) genes are an apparently reliable “weapon” to protect plants from infection by powdery mildew fungi, as they confer durable broad-spectrum resistance. Originally detected as a natural mutation in an Ethiopian barley landrace, this so-called mlo-based resistance has been successfully employed in European barley agriculture for nearly four decades. More recently, mlo-mediated resistance was discovered to be inducible in virtually every plant species of economic or scientific relevance. By now, mlo resistance has been found (as natural mutants) or generated (by induced mutagenesis, gene silencing, and targeted or nontargeted gene knock-out) in a broad range of monocotyledonous and dicotyledonous plant species. Here, we review features of mlo resistance in barley, discuss approaches to identify the appropriate Mlo gene targets to induce mlo-based resistance, and consider the issue of pleiotropic effects often associated with mlo-mediated immunity, which can harm plant yield and quality. We portray mlo-based resistance as an apparently universal and effective weapon to defeat powdery mildew disease in a multitude of plant species.

scholarly journals Chemical suppressors of mlo-mediated powdery mildew resistance

2017 ◽  
Vol 37 (6) ◽  
Author(s):  
Hongpo Wu ◽  
Mark Kwaaitaal ◽  
Roxana Strugala ◽  
Ulrich Schaffrath ◽  
Paweł Bednarek ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Powdery Mildew Resistance ◽  
Brefeldin A ◽  
Loss Of Function ◽  
Mildew Resistance ◽  
Inhibitor Analysis ◽  
Guanine Derivatives ◽  
Powdery Mildew Pathogen ◽  
Inhibitor Screen ◽  
Molecular Components

Loss-of-function of barley mildew locus o (Mlo) confers durable broad-spectrum penetration resistance to the barley powdery mildew pathogen, Blumeria graminis f. sp. hordei (Bgh). Given the importance of mlo mutants in agriculture, surprisingly few molecular components have been identified to be required for this type of resistance in barley. With the aim to identify novel cellular factors contributing to mlo-based resistance, we devised a pharmacological inhibitor screen. Of the 41 rationally chosen compounds tested, five caused a partial suppression of mlo resistance in barley, indicated by increased levels of Bgh host cell entry. These chemicals comprise brefeldin A (BFA), 2′,3′-dideoxyadenosine (DDA), 2-deoxy-d-glucose, spermidine, and 1-aminobenzotriazole. Further inhibitor analysis corroborated a key role for both anterograde and retrograde endomembrane trafficking in mlo resistance. In addition, all four ribonucleosides, some ribonucleoside derivatives, two of the five nucleobases (guanine and uracil), some guanine derivatives as well as various polyamines partially suppress mlo resistance in barley via yet unknown mechanisms. Most of the chemicals identified to be effective in partially relieving mlo resistance in barley also to some extent compromised powdery mildew resistance in an Arabidopsis mlo2 mlo6 double mutant. In summary, our study identified novel suppressors of mlo resistance that may serve as valuable probes to unravel further the molecular processes underlying this unusual type of disease resistance.

scholarly journals Characterization of evolutionarily conserved key players affecting eukaryotic flagellar motility and fertility using a moss model

2019 ◽  
Author(s):  
Rabea Meyberg ◽  
Pierre-François Perroud ◽  
Fabian B. Haas ◽  
Lucas Schneider ◽  
Thomas Heimerl ◽  
...  
Keyword(s):  
Male Infertility ◽  
Male Fertility ◽  
Physcomitrella Patens ◽  
Expression Profiles ◽  
Coiled Coil ◽  
Flagellar Motility ◽  
Loss Of Function ◽  
Male Gametes ◽  
Evolutionarily Conserved ◽  
Fertility Difference

AbstractDefects in flagella/cilia are often associated with infertility and disease. Motile male gametes (sperm cells) with flagella are an ancestral eukaryotic trait that has been lost in several lineages, for example in flowering plants. Here, we made use of a phenotypic male fertility difference between two moss (Physcomitrella patens) strains to explore spermatozoid function. We compare genetic and epigenetic variation as well as expression profiles between the Gransden and Reute strain to identify a set of genes associated with moss male infertility. Defects in mammal and algal homologs of these genes coincide with a loss of fertility, demonstrating the evolutionary conservation of flagellar function related to male fertility across kingdoms. As a proof of principle, we generated a loss-of-function mutant of a coiled-coil domain containing 39 (ccdc39) gene that is part of the flagellar hydin network. Indeed, the Ppccdc39 mutant resembles the male infertile Gransden strain phenotype. Potentially, several somatic (epi-)mutations occurred during prolonged vegetative propagation of P. patens Gransden, causing regulatory differences of e.g. the homeodomain transcription factor BELL1. Probably these somatic changes are causative for the observed male fertility. We propose that P. patens spermatozoids might be employed as an easily accessible system to study male infertility of human and animals.

scholarly journals Allelic barley MLA immune receptors recognize sequence-unrelated avirulence effectors of the powdery mildew pathogen

2016 ◽  
Vol 113 (42) ◽  
pp. E6486-E6495 ◽  
Author(s):  
Xunli Lu ◽  
Barbara Kracher ◽  
Isabel M. L. Saur ◽  
Saskia Bauer ◽  
Simon R. Ellwood ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Gene Clusters ◽  
Specific Cell ◽  
Resistance Locus ◽  
Powdery Mildew Fungus ◽  
Evolutionarily Conserved ◽  
Genes Encoding ◽  
Barley Leaves ◽  
Allele Specific ◽  
Powdery Mildew Pathogen

Disease-resistance genes encoding intracellular nucleotide-binding domain and leucine-rich repeat proteins (NLRs) are key components of the plant innate immune system and typically detect the presence of isolate-specific avirulence (AVR) effectors from pathogens. NLR genes define the fastest-evolving gene family of flowering plants and are often arranged in gene clusters containing multiple paralogs, contributing to copy number and allele-specific NLR variation within a host species. Barley mildew resistance locus a (Mla) has been subject to extensive functional diversification, resulting in allelic resistance specificities each recognizing a cognate, but largely unidentified, AVRa gene of the powdery mildew fungus, Blumeria graminis f. sp. hordei (Bgh). We applied a transcriptome-wide association study among 17 Bgh isolates containing different AVRa genes and identified AVRa1 and AVRa13, encoding candidate-secreted effectors recognized by Mla1 and Mla13 alleles, respectively. Transient expression of the effector genes in barley leaves or protoplasts was sufficient to trigger Mla1 or Mla13 allele-specific cell death, a hallmark of NLR receptor-mediated immunity. AVRa1 and AVRa13 are phylogenetically unrelated, demonstrating that certain allelic MLA receptors evolved to recognize sequence-unrelated effectors. They are ancient effectors because corresponding loci are present in wheat powdery mildew. AVRA1 recognition by barley MLA1 is retained in transgenic Arabidopsis, indicating that AVRA1 directly binds MLA1 or that its recognition involves an evolutionarily conserved host target of AVRA1. Furthermore, analysis of transcriptome-wide sequence variation among the Bgh isolates provides evidence for Bgh population structure that is partially linked to geographic isolation.

Cloning and Characterization of a Novel Wheat Glycoside Hydrolase Gene TaGlc2 Induced by Powdery Mildew Pathogen (Erysiphe graminis) Infection

2009 ◽  
Vol 35 (5) ◽  
pp. 786-794
Author(s):  
N PUDAKE Ramesh ◽  
Ming-Ming XIN ◽  
Yu-Jing YIN ◽  
Chao-Jie XIE ◽  
Zhong-Fu NI ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Glycoside Hydrolase ◽  
Erysiphe Graminis ◽  
Powdery Mildew Pathogen

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.

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