Staff Publications

Staff Publications

  • external user (warningwarning)
  • Log in as
  • language uk
  • About

    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

    We have a manual that explains all the features 

Records 1 - 20 / 50

  • help
  • print

    Print search results

  • export

    Export search results

  • alert
    We will mail you new results for this query: metisnummer==1058663
Check title to add to marked list
Corrigendum to "Proteome catalog of Zymoseptoria tritici captured during pathogenesis in wheat". [Fung. Genet. Biol. 79 (2015) 42-53]
Mbarek, Sarrah Ben; Cordewener, J.H.G. ; Lee, T.A.J. Van der; America, A.H.P. ; Gohari, Amir Mirzadi ; Mehrabi, Rahim ; Hamza, Sonia ; Wit, P.J.G.M. de; Kema, Gert - \ 2015
Fungal Genetics and Biology 82 (2015). - ISSN 1087-1845 - p. 291 - 291.
FPLC and liquid-chromatography mass spectrometry identify candidate necrosis-inducing proteins from culture filtrates of the fungal wheat pathogen Zymoseptoria tritici
M'Barek, S. Ben; Cordewener, J.H.G. ; Tabib Ghaffary, M.S. ; Lee, T.A.J. van der; Liu, Z. ; Mirzadi Gohari, A. ; Mehrabi, R. ; America, A.H.P. ; Friesen, T.L. ; Hamza, S. ; Stergiopoulos, I. ; Wit, P.J.G.M. de; Kema, G.H.J. - \ 2015
Fungal Genetics and Biology 79 (2015). - ISSN 1087-1845 - p. 54 - 62.
host-selective toxins - mycosphaerella-graminicola - stagonospora-nodorum - septoria-tritici - rhynchosporium-secalis - cladosporium-fulvum - ptr toxa - hydrogen-peroxide - barley pathogen - tan spot
Culture filtrates (CFs) of the fungal wheat pathogen Zymoseptoria tritici were assayed for necrosis-inducing activity after infiltration in leaves of various wheat cultivars. Active fractions were partially purified and characterized. The necrosis-inducing factors in CFs are proteinaceous, heat stable and their necrosis-inducing activity is temperature and light dependent. The in planta activity of CFs was tested by a time series of proteinase K (PK) co-infiltrations, which was unable to affect activity 30min after CF infiltrations. This suggests that the necrosis inducing proteins (NIPs) are either absent from the apoplast and likely actively transported into mesophyll cells or protected from the protease by association with a receptor. Alternatively, plant cell death signaling pathways might be fully engaged during the first 30min and cannot be reversed even after PK treatment. Further fractionation of the CFs with the highest necrosis-inducing activity involved fast performance liquid chromatography, SDS-PAGE and mass spectrometry. This revealed that most of the proteins present in the fractions have not been described before. The two most prominent ZtNIP encoding candidates were heterologously expressed in Pichia pastoris and subsequent infiltration assays showed their differential activity in a range of wheat cultivars.
Proteome catalog of Zymoseptoria tritici captured during pathogenesis in wheat
M'Barek, S. Ben; Cordewener, J.H.G. ; Lee, T.A.J. van der; America, A.H.P. ; Mirzadi Gohari, A. ; Mehrabi, R. ; Hamza, S. ; Wit, P.J.G.M. de; Kema, G.H.J. - \ 2015
Fungal Genetics and Biology 79 (2015)June. - ISSN 1087-1845 - p. 42 - 53.
wall-degrading enzymes - fungus mycosphaerella-graminicola - programmed cell-death - cladosporium-fulvum - septoria-tritici - plant-pathogen - magnaporthe-grisea - disease resistance - hydrogen-peroxide - blotch pathogen
Zymoseptoria tritici is an economically important pathogen of wheat. However, the molecular basis of pathogenicity on wheat is still poorly understood. Here, we present a global survey of the proteins secreted by this fungus in the apoplast of resistant (cv. Shafir) and susceptible (cv. Obelisk) wheat cultivars after inoculation with reference Z. tritici strain IPO323. The fungal proteins present in apoplastic fluids were analyzed by gel electrophoresis and by data-independent acquisition liquid chromatography/mass spectrometry (LC/MS(E)) combined with data-dependent acquisition LC-MS/MS. Subsequent mapping mass spectrometry-derived peptide sequence data against the genome sequence of strain IPO323 identified 665 peptides in the MS(E) and 93 in the LC-MS/MS mode that matched to 85 proteins. The identified fungal proteins, including cell-wall degrading enzymes and proteases, might function in pathogenicity, but the functions of many remain unknown. Most fungal proteins accumulated in cv. Obelisk at the onset of necrotrophy. This inventory provides an excellent basis for future detailed studies on the role of these genes and their encoded proteins during pathogenesis in wheat
Effector discovery in the fungal wheat pathogen Zymoseptoria tritici
Mirzadi Gohari, A. ; Ware, S.B. ; Wittenberg, A.H.J. ; Mehrabi, R. ; M'Barek, S. Ben; Verstappen, E.C.P. ; Lee, T.A.J. van der; Robert, O. ; Schouten, H.J. ; Wit, P.J.G.M. de; Kema, G.H.J. - \ 2015
Molecular Plant Pathology 16 (2015)9. - ISSN 1464-6722 - p. 931 - 945.
Fungal plant pathogens, such as Zymoseptoria tritici (formerly known as Mycosphaerella graminicola), secrete repertoires of effectors to facilitate infection or trigger host defence mechanisms. The discovery and functional characterization of effectors provides valuable knowledge that can contribute to the design of new and effective disease management strategies. Here, we combined bioinformatics approaches with expression profiling during pathogenesis to identify candidate effectors of Z.¿tritici. In addition, a genetic approach was conducted to map quantitative trait loci (QTLs) carrying putative effectors, enabling the validation of both complementary strategies for effector discovery. In¿planta expression profiling revealed that candidate effectors were up-regulated in successive waves corresponding to consecutive stages of pathogenesis, contrary to candidates identified by QTL mapping that were, overall, expressed at low levels. Functional analyses of two top candidate effectors (SSP15 and SSP18) showed their dispensability for Z.¿tritici pathogenesis. These analyses reveal that generally adopted criteria, such as protein size, cysteine residues and expression during pathogenesis, may preclude an unbiased effector discovery. Indeed, genetic mapping of genomic regions involved in specificity render alternative effector candidates that do not match the aforementioned criteria, but should nevertheless be considered as promising new leads for effectors that are crucial for the Z.¿tritici–wheat pathosystem
MAP Kinase Phosphorylation and cAMP assessment in fungi
Mehrabi, R. ; M'Barek, S. Ben; Saidi, A. ; Abrinbana, M. ; Wit, P.J.G.M. de; Kema, G.H.J. - \ 2012
In: Plant Fungal Pathogens : Methods and Protocols / Bolton, M.D.D., Thomma, B.P.H.J.P., New York, Dordrecht, Heidelberg, London : Springer (Methods in Molecular Biology 835) - ISBN 9781617795008 - p. 571 - 584.
The cyclic AMP (cAMP) signaling and mitogen-activated protein (MAP) kinase pathways are the most important signal transduction pathways in eukaryotes. In many plant pathogenic fungi they play pivotal roles in virulence and development. Identifi cation and understanding the role of signal transduction pathways in regulation of cellular responses require robust biochemical techniques. Determination of both the phosphorylation status of MAPKs and the intracellular levels of cAMP is required to unravel the function of these pathways during adaptation of fungi to environmental stress conditions or when particular fungal genes are disrupted or silenced. Here we describe protocols to determine the phosphorylation status of three different MAPKs including Fus3, Slt2 and Hog1 as well as a protocol to measure the intracellular levels of cAMP levels. These protocols can be adapted for a wide range of fungi
Ontwikkeling resistente tarwe tegen Mycosphaerella dichterbij
Mbarek, Sarrah Ben - \ 2011
Developing wheat with resistance against Mycosphaerella fungus difficult but closer than ever
Mbarek, Sarrah Ben - \ 2011
Developing wheat varieties with resistance to the feared leaf blotch disease may be very difficult, but recent studies carried out at Wageningen UR have brought it closer than ever. This is clear from research of the Dutch-Tunisian Sarrah Ben M’Barek-Ben Romdhane who obtained her doctorate on this subject at Wageningen University, part of Wageningen UR, on 17 October. Ben M’Barek and her colleagues mapped the complete DNA of the pathogen that causes septoria leaf blotch - the fungus Mycosphaerella graminicola. They showed that the fungus can lose entire chromosomes during sexual reproduction without any visible effect. Ben M’Barek also found that the fungus can attack wheat plants in various ways. These findings explain why it has been so difficult thus far to develop resistant wheat varieties. The new knowledge provides clues that will stimulate the development of those varieties, increasing the security and sustainability of food production. Wheat is the main food crop for regions such as North Africa and the Middle East, where it is severely threatened by the fungus Mycosphaerella graminicola, the cause of so-called septoria leaf blotch. Unfortunately, as no useable wheat varieties are resistant against the fungus, it has to be controlled with fungicide and continues to reduce food yields. This could be changed by greater insight into the genetics of the pathogen and a better understanding of the interaction between pathogen and plant.
Developing wheat with resistance against Mycosphaerella fungus difficult but closer than ever
Mbarek, Sarrah Ben - \ 2011
Developing wheat varieties with resistance to the feared leaf blotch disease may be very difficult, but recent studies carried out at Wageningen UR have brought it closer than ever. This is clear from research of the Dutch-Tunisian Sarrah Ben M’Barek-Ben Romdhane who obtained her doctorate on this subject at Wageningen University, part of Wageningen UR, on 17 October. Ben M’Barek and her colleagues mapped the complete DNA of the pathogen that causes septoria leaf blotch - the fungus Mycosphaerella graminicola. They showed that the fungus can lose entire chromosomes during sexual reproduction without any visible effect. Ben M’Barek also found that the fungus can attack wheat plants in various ways. These findings explain why it has been so difficult thus far to develop resistant wheat varieties. The new knowledge provides clues that will stimulate the development of those varieties, increasing the security and sustainability of food production. Wheat is the main food crop for regions such as North Africa and the Middle East, where it is severely threatened by the fungus Mycosphaerella graminicola, the cause of so-called septoria leaf blotch. Unfortunately, as no useable wheat varieties are resistant against the fungus, it has to be controlled with fungicide and continues to reduce food yields. This could be changed by greater insight into the genetics of the pathogen and a better understanding of the interaction between pathogen and plant.
Developing wheat with resistance against Mycosphaerella fungus difficult but closer than ever
Mbarek, Sarrah Ben - \ 2011
Developing wheat varieties with resistance to the feared leaf blotch disease may be very difficult, but recent studies carried out at Wageningen UR have brought it closer than ever. This is clear from research of the Dutch-Tunisian Sarrah Ben M’Barek-Ben Romdhane who obtained her doctorate on this subject at Wageningen University on 17 October. Ben M’Barek and her colleagues mapped the complete DNA of the pathogen that causes septoria leaf blotch - the fungus Mycosphaerella graminicola. They showed that the fungus can lose entire chromosomes during sexual reproduction without any visible effect. Ben M’Barek also found that the fungus can attack wheat plants in various ways. These findings explain why it has been so difficult thus far to develop resistant wheat varieties. The new knowledge provides clues that will stimulate the development of those varieties, increasing the security and sustainability of food production
Ontwikkeling resistentie tarwe tegen Mycosphaerella dichterbij
Mbarek, Sarrah Ben - \ 2011
Het ontwikkelen van tarwerassen met resistentie tegen bladvlekkenziekte is door recent onderzoek in Wageningen Universiteit dichterbij dan ooit. Dat blijkt uit het onderzoek waarop de Tunesische Sarrah Ben M’Barek-Ben Romdhane op 17 oktober promoveerde aan Wageningen Universiteit. Ben Romdhane bracht samen met collega’s het hele DNA in kaart van de veroorzaker van de bladvlekkenziekte, de schimmel Mycosphaerella graminicola. Ze liet zien dat de schimmel bij de sexuele voortplanting hele chromosomen kan kwijtraken zonder dat dat schade doet aan de schimmel
Bladvlekkenziekte resistente tarwerassen in de maak
Mbarek, Sarrah Ben - \ 2011
Wageningen ontrafelt DNA tarweschimmel
Mbarek, Sarrah Ben - \ 2011
Wageningen Universiteit heeft het DNA in kaart gebracht van de schimmel Mycosphaerella graminicola, die bladvlekkenziekte veroorzaakt in tarwe. Daardoor wordt het gemakkelijker tarwe te kweken die resistent is tegen de schadelijke schimmelziekte. De Tunesische Sarrah Ben M'Barek-Ben Romdhane promoveerde afgelopen week aan Wageningen Univer-siteit. Zij bracht samen met collega's het hele DNA in kaart van de schimmel Mycosphaerella graminicola. Ben Romdhane toonde aan dat de schimmel bij de seksuele voortplanting hele chromosomen kan kwijtraken zonder dat dat schade doet aan de schimmel. Zij ontdekte daarnaast dat de schimmel op verschillende ma-nieren tarweplanten kan aanvallen. "Deze zaken maken duidelijk waarom het tot nu toe zo lastig is om re-sistente tarwerassen te ontwikkelen. De nieuwe kennis biedt aanknopingspunten om die rassen nu wél te ontwikkelen, en zo de voedselproductie zekerder en duurzamer te maken", meldt de universiteit
Genome structure and pathogenicity of the fungal wheat pathogen Mycosphaerella graminicola
M'Barek, S. Ben - \ 2011
Wageningen University. Promotor(en): Pierre de Wit, co-promotor(en): Gert Kema. - [S.l.] : S.n. - ISBN 9789085859970 - 229
triticum aestivum - triticum turgidum - tarwe - mycosphaerella graminicola - plantenziekteverwekkende schimmels - genoomstructuur - eiwitexpressieanalyse - pathogeniteit - pathogenesis-gerelateerde eiwitten - genomen - plasticiteit - plant-microbe interacties - wheat - plant pathogenic fungi - genomic structure - proteomics - pathogenicity - pathogenesis-related proteins - genomes - plasticity - plant-microbe interactions

The phytopathogenic fungus Mycosphaerella graminicola (Fuckel) J. Schröt. in Cohn (asexual stage: Zymoseptoria tritici (Desm.) Quaedvlieg & Crous) causes septoria tritici leaf blotch (STB) in wheat and is one of the most important diseases of this crop worldwide. However, STB control, mainly based on the use of resistant cultivars and fungicides, is significantly hampered by the limited understanding of the genetic and biochemical bases of pathogenicity, and mechanisms of infection and resistance in the host. M. graminicola has a very active sexual cycle under field conditions, which is an important driver of STB epidemics. Moreover, it results in high genetic diversity of field populations that causes a major challenge for the development and sustainable management of resistant cultivars and the discovery of new antifungal compounds. Understanding the role of the sexual and asexual life cycles on genome composition of this versatile pathogen and its infection strategy is crucial in order to develop novel control methods.

Chapter 1 is an introduction to the biology and pathogenicity of M. graminicola. In addition, it shortly describes the impact of improved and novel technologies on the speed, scope and scale of comparative genomics research.

Chapter 2 provides detailed genetic analyses of two M. graminicola mapping populations, using mainly DArT markers, and the analysis of the meiotic transmission of unequal chromosome numbers. Polymorphisms in chromosome length and number were frequently observed in progeny isolates, of which 15–20% lacked one or more chromosomes despite their presence in one or both parents, but these had no apparent effect on sexual and pathogenic fitness. M. graminicola has up to eight so called dispensable chromosomes that can be easily lost - collectively called the dispensome - which is, so far, the highest number of dispensable chromosomes reported in filamentous fungi. They represent small-sized chromosomes and make up 38% of the chromosome complement of this pathogen. Much of the observed genome plasticity is generated during meiosis and could explain the high adaptability of M. graminicola in the field. The generated linkage map was crucial for finishing the M. graminicola genome sequence.

Chapter 3 describes the M. graminicola genome sequence with highlights on genome structure and organization including the eight dispensable chromosomes. The genome comprises a core set of 13 chromosomes and a dispensome, consisting of eight chromosomes that are distinct from the core chromosomes in structure, gene and repeat content. The dispensome contains a higher frequency of transposons and the genes have a different codon use. Most of the genes present one the dispensome are also present on the core chromosomes but little synteny is observed neither between the M. graminicola dispensome and the core chromosomes nor with the chromosomes of other related Dothideomycetes. The dispensome likely originates from ancient horizontal transfer(s) from (an) unknown donor(s).

Chapter 4 shows a global analysis of proteins secreted by M. graminicola in apoplastic fluids during infection. It focuses mainly on fungal proteins secreted in a compatible interaction. The study showed that many of the annotated secreted proteins have putative functions in fungal pathogenicity, such as cell wall degrading enzymes and proteases, but the function of a substantial number of the identified proteins is unknown. During compatible interactions proteins are primarily secreted during the later stages. However, many pathogenesis-related host proteins, such as PR-2, PR-3 and PR-9, accumulated earlier and at higher concentrations during incompatible interactions, indicating that fungal effectors are recognized by resistant plants and trigger resistant gene-mediated defence responses, though without a visible hypersensitive response.

Chapter 5 further details the initial identification and characterization of necrosis-inducing proteins that are produced in culture filtrates (CFs) of M. graminicola. The necrosis-inducing activity of CFs is light dependent and inactivated by proteinase K and heat treatment (100C). This is reminiscent of the necrosis-inducing properties of host selective toxins of other Dothideomycete pathogens such as Stagonospora nodorum and Pyrenophora tritici-repentis. Subsequent purifications of CFs and mass spectrometry identified several candidate proteins with necrosis-inducing activity. Heterologous expression of the two most prominent proteins in Pichia pastoris produced sufficient quantities for infiltration assays in a panel of wheat cultivars that showed differential responses, suggesting specific recognition.

Chapter 6 provides a general discussion of the thesis and puts the results obtained in a broader perspective with a focus on the genome structure of M. graminicola and its function. In addition, aspects of the hemi-biotrophic lifestyle, the relevance of secreted proteins for the wheat-M. graminicola pathosystem in relation to gene-for-gene models and the potential implications for resistance breeding strategies are discussed.

Finished Genome of the Fungal Wheat Pathogen Mycosphaerella graminicola Reveals Dispensome Structure, Chromosome Plasticity, and Stealth Pathogenesis
Goodwin, S.B. ; M'Barek, S. Ben; Dhillon, B. ; Wittenberg, A.H.J. ; Crane, C.F. ; Hane, J.K. ; Foster, A.J. ; Lee, T.A.J. van der; Grimwood, J. ; Aerts, A. ; Antoniw, J. ; Bailey, A. ; Bluhm, B. ; Bowler, J. ; Bristow, J. ; Burgt, A. van der; Canto-Canché, B. ; Churchill, A.C.L. ; Conde-Ferràez, L. ; Cools, H.J. ; Coutinho, P.M. ; Csukai, M. ; Dehal, P. ; Wit, P.J.G.M. de; Donzelli, B. ; Geest, H.C. van de; Ham, R.C.H.J. van; Hammond-Kosack, K.E. ; Henrissat, B. ; Kilian, A. ; Kobayashi, A.K. ; Koopmann, E. ; Kourmpetis, Y. ; Kuzniar, A. ; Lindquist, E. ; Lombard, V. ; Maliepaard, C.A. ; Martins, N. ; Mehrabi, A. ; Nap, J.P.H. ; Ponomarenko, A. ; Rudd, J.J. ; Salamov, A. ; Schmutz, J. ; Schouten, H.J. ; Shapiro, H. ; Stergiopoulos, I. ; Torriani, S.F.F. ; Tu, H. ; Vries, R.P. de; Waalwijk, C. ; Ware, S.B. ; Wiebenga, A. ; Zwiers, L.H. ; Oliver, R.P. ; Grigoriev, I.V. ; Kema, G.H.J. - \ 2011
Plos Genetics 7 (2011)6. - ISSN 1553-7404 - 17 p.
magnaporthe-grisea - b-chromosomes - gene - host - organization - annotation - resistance - neurospora - expression - symbiosis
The plant-pathogenic fungus Mycosphaerella graminicola (asexual stage: Septoria tritici) causes septoria tritici blotch, a disease that greatly reduces the yield and quality of wheat. This disease is economically important in most wheat-growing areas worldwide and threatens global food production. Control of the disease has been hampered by a limited understanding of the genetic and biochemical bases of pathogenicity, including mechanisms of infection and of resistance in the host. Unlike most other plant pathogens, M. graminicola has a long latent period during which it evades host defenses. Although this type of stealth pathogenicity occurs commonly in Mycosphaerella and other Dothideomycetes, the largest class of plant-pathogenic fungi, its genetic basis is not known. To address this problem, the genome of M. graminicola was sequenced completely. The finished genome contains 21 chromosomes, eight of which could be lost with no visible effect on the fungus and thus are dispensable. This eight-chromosome dispensome is dynamic in field and progeny isolates, is different from the core genome in gene and repeat content, and appears to have originated by ancient horizontal transfer from an unknown donor. Synteny plots of the M. graminicola chromosomes versus those of the only other sequenced Dothideomycete, Stagonospora nodorum, revealed conservation of gene content but not order or orientation, suggesting a high rate of intra-chromosomal rearrangement in one or both species. This observed “mesosynteny” is very different from synteny seen between other organisms. A surprising feature of the M. graminicola genome compared to other sequenced plant pathogens was that it contained very few genes for enzymes that break down plant cell walls, which was more similar to endophytes than to pathogens. The stealth pathogenesis of M. graminicola probably involves degradation of proteins rather than carbohydrates to evade host defenses during the biotrophic stage of infection and may have evolved from endophytic ancestors. Author Summary The plant-pathogenic fungus Mycosphaerella graminicola causes septoria tritici blotch, one of the most economically important diseases of wheat worldwide and a potential threat to global food production. Unlike most other plant pathogens, M. graminicola has a long latent period during which it seems able to evade host defenses, and its genome appears to be unstable with many chromosomes that can change size or be lost during sexual reproduction. To understand its unusual mechanism of pathogenicity and high genomic plasticity, the genome of M. graminicola was sequenced more completely than that of any other filamentous fungus. The finished sequence contains 21 chromosomes, eight of which were different from those in the core genome and appear to have originated by ancient horizontal transfer from an unknown donor. The dispensable chromosomes collectively comprise the dispensome and showed extreme plasticity during sexual reproduction. A surprising feature of the M. graminicola genome was a low number of genes for enzymes that break down plant cell walls; this may represent an evolutionary response to evade detection by plant defense mechanisms. The stealth pathogenicity of M. graminicola may involve degradation of proteins rather than carbohydrates and could have evolved from an endophytic ancestor.
Horizontal gene and chromosome transfer in plantpathogenic fungi affecting host range
Mehrabi, R. ; Bahkali, A.H. ; Abd-Elsalam, K.A. ; M'Barek, S. Ben; Mirzadi Gohari, A. ; Karimi Jashini, M. ; Stergiopoulos, I. ; Kema, G.H.J. ; Wit, P.J.G.M. de - \ 2011
FEMS Microbiology Reviews 35 (2011)3. - ISSN 0168-6445 - p. 542 - 554.
conidial anastomosis tubes - japanese pear pathotype - polyketide t-toxin - alternaria-alternata - nectria-haematococca - cochliobolus-heterostrophus - fusarium-oxysporum - neurospora-crassa - hyphal fusion - colletotrichum-gloeosporioides
Plant pathogenic fungi adapt quickly to changing environments including overcoming plant disease resistance genes. This is usually achieved by mutations in single effector genes of the pathogens, enabling them to avoid recognition by the host plant. In addition, horizontal gene transfer (HGT) and horizontal chromosome transfer (HCT) provide a means for pathogens to broaden their host range. Recently, several reports have appeared in the literature on HGT, HCT and hybridization between plant pathogenic fungi that affect their host range, including species of Stagonospora/Pyrenophora, Fusarium and Alternaria. Evidence is given that HGT of the ToxA gene from Stagonospora nodorum to Pyrenophora tritici-repentis enabled the latter fungus to cause a serious disease in wheat. A nonpathogenic Fusarium species can become pathogenic on tomato by HCT of a pathogenicity chromosome from Fusarium oxysporum f.sp lycopersici, a wellknown pathogen of tomato. Similarly, Alternaria species can broaden their host range by HCT of a single chromosome carrying a cluster of genes encoding hostspecific toxins that enabled them to become pathogenic on new hosts such as apple, Japanese pear, strawberry and tomato, respectively. The mechanisms HGT and HCT and their impact on potential emergence of fungal plant pathogens adapted to new host plants will be discussed
Hunting for effectors-elicitors in the fungal wheat pathogen Mycosphaerella graminicola with a quantitative proteomic approach using comparative (label-free) LC-MSE
M'Barek, S. Ben; Cordewener, J.H.G. ; Lee, T.A.J. van der; America, A.H.P. ; Kema, G.H.J. - \ 2010
In: Book of Abstracts 10th European Conference on Fungal Genetics, Noordwijkerhout, the Netherlands, 29 March – 1 April 2010. - FEMS Federation of European Microbiological Societies - p. PR7.3 - PR7.3.
Septoria tritici blotch caused by the haploid ascomycete Mycosphaerella graminicola (Fuckel) J. Schröt. in Cohn, is the most important wheat disease in Europe. Despite the recent identification of 15 resistance genes and their potential application in breeding, disease control is currently achieved mainly by fungicides. The genome of M. graminicola has been sequenced and finished by the US. Department of Energy- Joint Genome Institute and together with the high quality of the genome annotation, the high-density genetic linkage maps, including 11 quantitative trait loci involved in species specificity as well as in cultivar-specificity (Ware et al. 2006; Wittenberg et al. 2007) this provides an excellent foundation for proteomic studies that focus on the pathogen side of the interaction. The lifestyle of M. graminicola is significantly different from other cereal pathogens. It is a hemibiotroph with an initial symptomless biotrophic and intercellular phase that is followed by a necrotrophic phase resulting in disease symptoms starting from approximately 14 days after infection. The switch from biotrophy to necrotrophy is poorly understood and we therefore have started experiments using established protocols for apoplast analysis from the Cladosporium-tomato pathosystem. Extracellular liquid (apoplast) was collected from (in)compatible interactions at several time points after inoculation. Proteins were extracted and digested with trypsin. The complex peptide digests were separated and detected with nano-UPLC-QTOF operating in an alternating mode of low and high collision energy. With this approach peptide abundances can be quantitatively compared between multiple complex protein samples. In the initial experiment 18 LCMS traces (6 samples in triplicate) were compared providing highly detailed quantification and identification. Using the identification algorithm 3150 peaks were identified, resulting in 1926 unique peptide sequences that were identified and quantified. We identified several proteins of M. graminicola that appear to be secreted in specific stages of the infection to the apoplast and currently study these candidate effectors of the M.graminicola-wheat interaction.
Hunting for effectors-elicitors in the fungal wheat pathogen Mycosphaerella graminicola with a quantitative proteomic approach using comparative (label-free) LC-MSE (PR7.3)
M'Barek, S. Ben; Cordewener, J.H.G. ; Lee, T.A.J. van der; America, A.H.P. ; Kema, G.H.J. - \ 2010
Septoria tritici blotch caused by the haploid ascomycete Mycosphaerella graminicola (Fuckel) J. Schröt. in Cohn, is the most important wheat disease in Europe. Despite the recent identification of 15 resistance genes and their potential application in breeding, disease control is currently achieved mainly by fungicides. The genome of M. graminicola has been sequenced and finished by the US. Department of Energy- Joint Genome Institute and together with the high quality of the genome annotation, the high-density genetic linkage maps, including 11 quantitative trait loci involved in species specificity as well as in cultivar-specificity (Ware et al. 2006; Wittenberg et al. 2007) this provides an excellent foundation for proteomic studies that focus on the pathogen side of the interaction. The lifestyle of M. graminicola is significantly different from other cereal pathogens. It is a hemibiotroph with an initial symptomless biotrophic and intercellular phase that is followed by a necrotrophic phase resulting in disease symptoms starting from approximately 14 days after infection. The switch from biotrophy to necrotrophy is poorly understood and we therefore have started experiments using established protocols for apoplast analysis from the Cladosporium-tomato pathosystem. Extracellular liquid (apoplast) was collected from (in)compatible interactions at several time points after inoculation. Proteins were extracted and digested with trypsin. The complex peptide digests were separated and detected with nano-UPLC-QTOF operating in an alternating mode of low and high collision energy. With this approach peptide abundances can be quantitatively compared between multiple complex protein samples. In the initial experiment 18 LCMS traces (6 samples in triplicate) were compared providing highly detailed quantification and identification. Using the identification algorithm 3150 peaks were identified, resulting in 1926 unique peptide sequences that were identified and quantified. We identified several proteins of M. graminicola that appear to be secreted in specific stages of the infection to the apoplast and currently study these candidate effectors of the M.graminicola-wheat interaction
The dodge of blotch: Saving sex in Mycosphaerella graminicola
Kema, G.H.J. ; Ware, S.B. ; Lee, T.A.J. van der; Wittenberg, A.H.J. ; Díaz-Trujillo, C. ; Goodwin, S.B. ; Waard, M.A. de; M'Barek, S. Ben - \ 2010
In: Book of Abstracts 10th European Conference on Fungal Genetics, Noordwijkerhout, the Netherlands, 29 March – 1 April 2010. - - p. 37 - 37.
Mycosphaerella graminicola is the causal agent of septoria tritici blotch, currently the most important disease of wheat in Europe. Despite the recent identification of 15 resistance genes and their potential application in plant breeding, disease control is currently achieved mainly by fungicides. However, fungicide resistance development in natural M. graminicola populations frequently occurs and is a serious concern. Depending on the fungicides this may develop gradually, such as with resistance to azoles, or much more rapidly as was observed for strobilurin fungicides. In order to understand this rapid spread of resistance we have performed a range of crossing experiments that demonstrate that external stress factors hamper disease development but cannot prevent sexual development. As M. graminicola is a heterothallic bipolar pathogen, sexual development requires two mating partners - carrying different mat alleles (mat1-1 or mat 1-2) - that both produce female and male organs. We use an in planta crossing protocol that reliably enables the isolation of segregating/mapping populations. The first stress factor that we used was host resistance. Various crosses on a range of cereal hosts indicated that sex always takes place as long as one of the mating partners is virulent. Thus, even an avirulent isolate that does not establish a compatible interaction with the host plant is perfectly able to enter into the sexual process resulting in viable ascospores. As a consequence the genes of such an avirulent isolate are transmitted to subsequent generations. This is fundamentally different from many other host-pathosystems where avirulent isolates - and their genes - are lost in subsequent generations. We used strobilurin fungicides as a second stress factor by crossing sensitive and resistant isolates under various strobilurin concentrations (3- 200%). Although strobilurins prevent disease development of sensitive isolates, and as a consequence minimize biomass, abundant sexual development occurred under all conditions, thus irrespective of the applied strobilurin concentration. Moreover, our results showed that the ‘stressed’ mating partner – the sensitive parent – acted as the preferred paternal partner. Thus, external stress factors on avirulent or sensitive isolates do not preclude the production of M. graminicola spermatia that effectuate viable ascospore production. The fact that the sensitive isolates are preferred paternal donors – and consequently the resistant strains are maternal donors – in the sexual process resulted in major shifts in strobilurin resistance in the segregating populations as the target site for strobilurins is on the mitochondrial genome. A minimal dose of 6% strobilurin already rendered entire populations resistant to these compounds. This explains the rapid pan-European spread of strobilurin resistance in M. graminicola, likely in temporally and geographically independent occasions, with no loss of nuclear genetic variation. The recently discovered genome plasticity of M. graminicola may contribute to its ability to overcome environmentally adverse conditions.
Outstanding: the dispensable chromosomes of Mycosphaerella graminicola
Mbarek, Sarrah Ben - \ 2009
Outstanding: the dispensable chromosomes of Mycosphaerella graminicola
M'Barek, S. Ben; Lee, T.A.J. van der; Wittenberg, A.H.J. ; Ware, S.B. ; Maliepaard, C.A. ; Crane, C.F. ; Dhillon, B. ; Goodwin, S.B. ; Schouten, H.J. ; Kema, G.H.J. - \ 2009
In: Plenary Session Abstracts. 25th Fungal Genetics Conference, Asilomar, USA, 17-22 March 2009. - Kansas City, USA : FGSC - p. 82 (#102) - 82 (#102).
Analysis of two genetic linkage maps of the wheat pathogen Mycosphaerella graminicola identified dispensable chromosomes that were present in both parents but absent in 15-20 % of the progeny. These Copy number Polymorphisms (CNPs) were confirmed with a Comparative Genomic Hybridization whole-genome array based on the finished genome of M. graminicola (http://genome.jgi-psf.org). Chromosomes 14- 21 were frequently absent among isolates, without visible effect on viability or virulence, whereas chromosomes 1-13 were invariably present. Genetic analyses showed that CNPs arises during meiosis, usually from nondisjunction at anaphase II. Overall, M. graminicola has the highest number of dispensable chromosomes reported. Varying from 0.41 to 0.77 Mbp, they comprise 38% of the chromosome number and 11.6% of the genome. The dispensable chromosomes are smaller and have significantly lower gene densities. Most of their genes are duplicated on the essential chromosomes and show a different codon usage. Dispensable chromosomes also contained a higher density of transposons, pseudogenes, and unclassified genes, which could encode novel proteins. Moreover, the dispensable chromosomes show extremely low synteny with other Dothideomycete genomes. We hypothesize that the dispensable chromosomes of M. graminicola are adaptive in some yet unknown way http://www.fgsc.net/25thfgc/fgc25.htm
Check title to add to marked list
<< previous | next >>

Show 20 50 100 records per page

 
Please log in to use this service. Login as Wageningen University & Research user or guest user in upper right hand corner of this page.