Discovery and Characterization of a Novel Tomato mlo Mutant from an EMS Mutagenized Micro-Tom Population

In tomato (Solanum lycopersicum), there are at least three SlMLO (Mildew resistance Locus O) genes acting as susceptibility genes for the powdery mildew disease caused by Oidium neolycopersici, namely SlMLO1, SlMLO5 and SlMLO8. Of the three homologs, the SlMLO1 gene plays a major role since a natural mutant allele called ol-2 can almost completely prevent fungal penetration by formation of papillae. The ol-2 allele contains a 19-bp deletion in the coding sequence of the SlMLO1 gene, resulting in a premature stop codon within the second cytoplasmic loop of the predicted protein. In this study, we have developed a new genetic resource (M200) in the tomato cv. Micro-Tom genetic background by means of ethyl methane sulfonate (EMS) mutagenesis. The mutant M200 containing a novel allele (the m200 allele) of the tomato SlMLO1 gene showed profound resistance against powdery mildew with no fungal sporulation. Compared to the coding sequence of the SlMLO1 gene, the m200 allele carries a point mutation at T65A. The SNP results in a premature stop codon L22* located in the first transmembrane domain of the complete SlMLO1 protein. The length of the predicted protein is 21 amino acids, while the SlMLO1 full-length protein is 513 amino acids. A high-resolution melting (HRM) marker was developed to distinguish the mutated m200 allele from the SlMLO1 allele in backcross populations. The mutant allele conferred recessive resistance that was associated with papillae formation at fungal penetration sites of plant epidermal cells. A comprehensive list of known mlo mutations found in natural and artificial mutants is presented, which serves as a particularly valuable resource for powdery mildew resistance breeding.

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Flow studies on human GPVI-deficient blood under coagulating and noncoagulating conditions

Blood Advances ◽

10.1182/bloodadvances.2020001761 ◽

2020 ◽

Vol 4 (13) ◽

pp. 2953-2961 ◽

Cited By ~ 5

Author(s):

Magdolna Nagy ◽

Gina Perrella ◽

Amanda Dalby ◽

M. Francisca Becerra ◽

Lourdes Garcia Quintanilla ◽

...

Keyword(s):

Von Willebrand Factor ◽

Transmembrane Domain ◽

Stop Codon ◽

Premature Stop Codon ◽

Glycoprotein Vi ◽

Heterozygous Variant ◽

Platelet Aggregates ◽

Von Willebrand ◽

Willebrand Factor

Abstract The role of glycoprotein VI (GPVI) in platelets was investigated in 3 families bearing an insertion within the GP6 gene that introduces a premature stop codon prior to the transmembrane domain, leading to expression of a truncated protein in the cytoplasm devoid of the transmembrane region. Western blotting and flow cytometry of GP6hom (homozygous) platelets confirmed loss of the full protein. The level of the Fc receptor γ-chain, which associates with GPVI in the membrane, was partially reduced, but expression of other receptors and signaling proteins was not altered. Spreading of platelets on collagen and von Willebrand factor (which supports partial spreading) was abolished in GP6hom platelets, and spreading on uncoated glass was reduced. Anticoagulated whole blood flowed over immobilized collagen or a mixture of von Willebrand factor, laminin, and rhodocytin (noncollagen surface) generated stable platelet aggregates that express phosphatidylserine (PS). Both responses were blocked on the 2 surfaces in GP6hom individuals, but adhesion was not altered. Thrombin generation was partially reduced in GP6hom blood. The frequency of the GP6het (heterozygous) variant in a representative sample of the Chilean population (1212 donors) is 2.9%, indicating that there are ∼4000 GP6hom individuals in Chile. These results demonstrate that GPVI supports aggregation and PS exposure under flow on collagen and noncollagen surfaces, but not adhesion. The retention of adhesion may contribute to the mild bleeding diathesis of GP6hom patients and account for why so few of the estimated 4000 GP6hom individuals in Chile have been identified.

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Two Seven-Transmembrane Domain MILDEW RESISTANCE LOCUS O Proteins Cofunction in Arabidopsis Root Thigmomorphogenesis

The Plant Cell ◽

10.1105/tpc.108.062653 ◽

2009 ◽

Vol 21 (7) ◽

pp. 1972-1991 ◽

Cited By ~ 56

Author(s):

Zhongying Chen ◽

Sandra Noir ◽

Mark Kwaaitaal ◽

H. Andreas Hartmann ◽

Ming-Jing Wu ◽

...

Keyword(s):

Transmembrane Domain ◽

Resistance Locus ◽

Arabidopsis Root ◽

Mildew Resistance

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Identification and mapping of PmSE5785, a new recessive powdery mildew resistance locus, in synthetic hexaploid wheat

Euphytica ◽

10.1007/s10681-015-1560-7 ◽

2015 ◽

Vol 207 (3) ◽

pp. 619-626 ◽

Cited By ~ 6

Author(s):

Yajuan Wang ◽

Changyou Wang ◽

Wei Quan ◽

Xiujuan Jia ◽

Ying Fu ◽

...

Keyword(s):

Powdery Mildew ◽

Hexaploid Wheat ◽

Powdery Mildew Resistance ◽

Synthetic Hexaploid Wheat ◽

Resistance Locus ◽

Mildew Resistance ◽

Synthetic Hexaploid

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Naturally Occurring Broad-Spectrum Powdery Mildew Resistance in a Central American Tomato Accession Is Caused by Loss of Mlo Function

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-21-1-0030 ◽

2008 ◽

Vol 21 (1) ◽

pp. 30-39 ◽

Cited By ~ 171

Author(s):

Yuling Bai ◽

Stefano Pavan ◽

Zheng Zheng ◽

Nana F. Zappel ◽

Anja Reinstädler ◽

...

Keyword(s):

Powdery Mildew ◽

Broad Spectrum ◽

Powdery Mildew Resistance ◽

Candidate Gene Approach ◽

Loss Of Function ◽

Virus Induced Gene Silencing ◽

Coding Region ◽

Oidium Neolycopersici ◽

Tomato Cultivar ◽

Mildew Resistance

The resistant cherry tomato (Solanum lycopersicum var. cerasiforme) line LC-95, derived from an accession collected in Ecuador, harbors a natural allele (ol-2) that confers broad-spectrum and recessively inherited resistance to powdery mildew (Oidium neolycopersici). As both the genetic and phytopathological characteristics of ol-2–mediated resistance are reminiscent of powdery mildew immunity conferred by loss-of-function mlo alleles in barley and Arabidopsis, we initiated a candidate-gene approach to clone Ol-2. A tomato Mlo gene (SlMlo1) with high sequence-relatedness to barley Mlo and Arabidopsis AtMLO2 mapped to the chromosomal region harboring the Ol-2 locus. Complementation experiments using transgenic tomato lines as well as virus-induced gene silencing assays suggested that loss of SlMlo1 function is responsible for powdery mildew resistance conferred by ol-2. In progeny of a cross between a resistant line bearing ol-2 and the susceptible tomato cultivar Moneymaker, a 19-bp deletion disrupting the SlMlo1 coding region cosegregated with resistance. This polymorphism results in a frameshift and, thus, a truncated nonfunctional SlMlo1 protein. Our findings reveal the second example of a natural mlo mutant that possibly arose post-domestication, suggesting that natural mlo alleles might be evolutionarily short-lived due to fitness costs related to loss of mlo function.

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Isolation of TIR and nonTIR NBS–LRR resistance gene analogues and identification of molecular markers linked to a powdery mildew resistance locus in chestnut rose (Rosa roxburghii Tratt)

Theoretical and Applied Genetics ◽

10.1007/s00122-005-0002-7 ◽

2005 ◽

Vol 111 (5) ◽

pp. 819-830 ◽

Cited By ~ 40

Author(s):

Qiang Xu ◽

Xiaopeng Wen ◽

Xiuxin Deng

Keyword(s):

Molecular Markers ◽

Powdery Mildew ◽

Resistance Gene ◽

Powdery Mildew Resistance ◽

Resistance Locus ◽

Mildew Resistance ◽

Chestnut Rose ◽

Rosa Roxburghii Tratt ◽

Rosa Roxburghii

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Synergistic Activation of Defense Responses in Arabidopsis by Simultaneous Loss of the GSL5 Callose Synthase and the EDR1 Protein Kinase

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-23-5-0578 ◽

2010 ◽

Vol 23 (5) ◽

pp. 578-584 ◽

Cited By ~ 19

Author(s):

Anna Wawrzynska ◽

Natalie L. Rodibaugh ◽

Roger W. Innes

Keyword(s):

Powdery Mildew ◽

Positional Cloning ◽

Stop Codon ◽

Premature Stop Codon ◽

Defense Responses ◽

Loss Of Function ◽

Callose Synthase ◽

Synergistic Activation ◽

Golovinomyces Cichoracearum ◽

Inducible Gene

Loss-of-function mutations in the EDR1 gene of Arabidopsis confer enhanced resistance to Golovinomyces cichoracearum (powdery mildew). Disease resistance mediated by the edr1 mutation is dependent on an intact salicylic acid (SA) signaling pathway, but edr1 mutant plants do not constitutively express the SA-inducible gene PR-1 and are not dwarfed. To identify other components of the EDR1 signaling network, we screened for mutations that enhanced the edr1 mutant phenotype. Here, we describe an enhancer of edr1 mutant, eed3, which forms spontaneous lesions in the absence of pathogen infection, constitutively expresses both SA- and methyl jasmonate (JA)–inducible defense genes, and is dwarfed. Positional cloning of eed3 revealed that the mutation causes a premature stop codon in GLUCAN SYNTHASE-LIKE 5 (GSL5, also known as POWDERY MILDEW RESISTANT 4), which encodes a callose synthase required for pathogen-induced callose production. Significantly, gsl5 single mutants do not constitutively express PR-1 or AtERF1 (a JA-inducible gene) and are not dwarfed. Thus, loss of both EDR1 and GSL5 function has a synergistic effect. Our data suggest that EDR1 and GSL5 negatively regulate SA and JA production or signaling by independent mechanisms and that negative regulation of defense signaling by GSL5 may be independent of callose production.

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Mutants of the Zebrafish K+ Channel Hcn2b Exhibit Epileptic-like Behaviors

International Journal of Molecular Sciences ◽

10.3390/ijms222111471 ◽

2021 ◽

Vol 22 (21) ◽

pp. 11471

Author(s):

Roberto Rodríguez-Ortiz ◽

Ataúlfo Matínez-Torres

Keyword(s):

Heart Rate ◽

Danio Rerio ◽

Mutant Allele ◽

Stop Codon ◽

Premature Stop Codon ◽

K Channel ◽

Genetic Defects ◽

Hcn Channels ◽

Membrane Hyperpolarization ◽

Heart Malformations

Epilepsy is a chronic neurological disorder that affects 50 million people worldwide. The most common form of epilepsy is idiopathic, where most of the genetic defects of this type of epilepsy occur in ion channels. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are activated by membrane hyperpolarization, and are mainly expressed in the heart and central and peripheral nervous systems. In humans, four HCN genes have been described, and emergent clinical data shows that dysfunctional HCN channels are involved in epilepsy. Danio rerio has become a versatile organism to model a wide variety of diseases. In this work, we used CRISPR/Cas9 to generate hcn2b mutants in zebrafish, and characterized them molecularly and behaviorally. We obtained an hcn2b mutant allele with an 89 bp deletion that produced a premature stop codon. The mutant exhibited a high mortality rate in its life span, probably due to its sudden death. We did not detect heart malformations or important heart rate alterations. Absence seizures and moderate seizures were observed in response to light. These seizures rarely caused instant death. The results show that mutations in the Hcn2b channel are involved in epilepsy and provide evidence of the advantages of zebrafish to further our understanding of the pathogenesis of epilepsy.

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Heterogenous Expression of Glycoprotein lb, IX and V in Platelets from Two Patients with Bernard-Soulier Syndrome Caused by Different Genetic Abnormalities

Thrombosis and Haemostasis ◽

10.1055/s-0038-1649956 ◽

1995 ◽

Vol 74 (06) ◽

pp. 1411-1415 ◽

Cited By ~ 49

Author(s):

Masaaki Noda ◽

Kingo Fujimura ◽

Toshiro Takafuta ◽

Takeshi Shimomura ◽

Tetsuro Fujlmoto ◽

...

Keyword(s):

Complex Analysis ◽

Transmembrane Domain ◽

Stop Codon ◽

Expression Patterns ◽

Premature Stop Codon ◽

Surface Expression ◽

Coding Region ◽

Genetic Changes ◽

Pcr Products ◽

Bernard Soulier Syndrome

SummaryBernard-Soulier syndrome (BSS) is a rare inherited bleeding disorder, which is caused by deficiency or decrease of the platelet GPIb/IX/V complex. Analysis of two patients with BSS by How cytometry of the blood revealed different expression patterns of the components of the GPIb/IX/V complex. In case 1, GPIX was completely absent but residual amounts of GPIbα and GPV were detectable; in case 2, GPIbα was completely absent. We amplified the coding regions of GPIbα, GPIbß, GPV, and GPIX from the patients’ genomic DNA with the polymerase chain reaction (PCR) and sequenced the PCR products. In case 1, we identified a point mutation in the GPIX coding region that changes the codon for tryptophan-126 (TGG) to a nonsense codon (TGA). In case 2, we found a deletion of nucleotide within seven adenine repeats at the position of 1932 to 1938 in the coding region of GPIbα, which causes a frame shift that results in 58 altered amino acids and a premature stop codon. These genetic changes alter the transmembrane domain of GPIX or GPIbα and, therefore, would prevent proper insertion of the proteins in the plasma membrane. Thus, abnormality of a single component protein (GPIX or GPIbα) alters the assembly of the GPIb/IX/V complex and causes heterogenous surface expression of GPIbα, GPV and GPIX.

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RMo1 Confers Blast Resistance in Barley and Is Located within the Complex of Resistance Genes Containing Mla, a Powdery Mildew Resistance Gene

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-19-1034 ◽

2006 ◽

Vol 19 (9) ◽

pp. 1034-1041 ◽

Cited By ~ 21

Author(s):

Tsuyoshi Inukai ◽

M. Isabel Vales ◽

Kiyosumi Hori ◽

Kazuhiro Sato ◽

Patrick M. Hayes

Keyword(s):

Powdery Mildew ◽

Linkage Map ◽

Resistance Gene ◽

Resistance Genes ◽

Rice Blast ◽

Powdery Mildew Resistance ◽

Blast Disease ◽

Grass Species ◽

Resistance Locus ◽

Mildew Resistance

Isolates of Magnaporthe oryzae (the causal agent of rice blast disease) can infect a range of grass species, including barley. We report that barley Hordeum vulgare cv. Baronesse and an experimental line, BCD47, show a range of resistance reactions to infection with two rice blast isolates. The complete resistance of Baronesse to the isolate Ken 54–20 is controlled by a single dominant gene, designated RMo1. RMo1 mapped to the same linkage map position on chromosome 1H as the powdery mildew resistance locus Mla and an expressed sequence tag (k04320) that corresponds to the barley gene 711N16.16. A resistance quantitative trait locus (QTL), at which Baronesse contributed the resistance allele, to the isolate Ken 53–33 also mapped at the same position as RMo1. Synteny analysis revealed that a corresponding region on rice chromosome 5 includes the bacterial blight resistance gene xa5. These results indicate that a defined region on the short arm of barley chromosome 1H, including RMo1 and Mla, harbors genes conferring qualitative and quantitative resistance to multiple pathogens. The partial resistance of BCD47 to Ken53–33 is determined by alleles at three QTL, two of which coincide with the linkage map positions of the mildew resistance genes mlo and Mlf.

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