Staff Publications

Staff Publications

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    '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.

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    We will mail you new results for this query: keywords==Pathogenicity
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Phylogeny and genetic diversity of the banana Fusarium wilt pathogen Fusarium oxysporum f. sp. cubense in the Indonesian centre of origin
Maryani, N. ; Lombard, L. ; Poerba, Y.S. ; Subandiyah, S. ; Crous, P.W. ; Kema, G.H.J. - \ 2019
Studies in Mycology 92 (2019). - ISSN 0166-0616 - p. 155 - 194.
11 New taxa - Morphology - New species - Panama disease - Pathogenicity - Tropical Race 4

Fusarium oxysporum f. sp. cubense (Foc), the causal agent of Fusarium wilt or Panama disease on banana, is one of the major constraints in banana production worldwide. Indonesia is the centre of origin for wild and cultivated bananas, which likely co-evolved with Foc. This study explored the widest possible genetic diversity of Foc by sampling across Indonesia at 34 geographically and environmentally different locations in 15 provinces at six islands. This resulted in a comprehensive collection of ∼200 isolates from 40 different local banana varieties. Isolates were identified and assessed using sequence analysis of the translation elongation factor-1alpha (tef1), the RNA polymerase II largest subunit (rpb1), and the RNA polymerase II second largest subunit (rpb2). Phylogenetic analyses of these genes allowed the identification of 180 isolates of Fusarium oxysporum f. sp. cubense (Foc), and 20 isolates of the Fusarium fujikuroi species complex (FFSC), the Fusarium incarnatum-equiseti species complex (FIESC), and the Fusarium sambucinum species complex (FSSC). Further analyses, incorporating a worldwide collection of Foc strains, revealed nine independent genetic lineages for Foc, and one novel clade in the Fusarium oxysporum species complex (FOSC). Selected isolates from each lineage were tested on the banana varieties Gros Michel and Cavendish to characterise their pathogenicity profiles. More than 65 % of the isolates were diagnosed as Tropical Race 4 (Foc-TR4) due to their pathogenicity to Cavendish banana, which supports the hypothesis that Foc-TR4 is of Indonesian origin. Nine independent genetic lineages for Foc are formally described in this study. This biodiversity has not been studied since the initial description of Foc in 1919. This study provides a detailed overview of the complexity of Fusarium wilt on banana and its diversity and distribution across Indonesia.

Differences in infectivity and pathogenicity of two Plantago asiatica mosaic virus isolates in lilies
Tanaka, Masashi ; Verbeek, Martin ; Takehara, Miki ; Pham, Khanh ; Lemmers, Miriam ; Slootweg, Casper ; Arie, Tsutomu ; Komatsu, Ken - \ 2018
European Journal of Plant Pathology (2018). - ISSN 0929-1873
Environmental effects - Infectivity - Necrosis - Ornamental lily - Pathogenicity - Plantago asiatica mosaic virus

Plantago asiatica mosaic virus (PlAMV) is a member of the genus Potexvirus in the family Alphaflexiviridae and has been isolated from a variety of host plants. In particular, PlAMV isolates from ornamental lilies (Lilium spp.) cause necrotic symptoms in these plants, which significantly reduces their commercial value. However, it has not been clear whether PlAMV isolates from other host plants differ in their infectivity and/or pathogenicity to ornamental lilies, and whether growth conditions affect infectivity and pathogenicity. In this study, we inoculated an edible lily species (Lilium leichtlinii) and seven varieties of ornamental lilies with two PlAMV isolates, an isolate from ornamental lily (PlAMV-OL) and an isolate from edible lily (PlAMV-Li1). We found that PlAMV-OL showed higher infection rates and exhibited necrotic symptoms more frequently in lilies than PlAMV-Li1. Moreover, we observed higher infection rates of PlAMV-OL in open field than in greenhouse, and higher rates of necrotic symptoms in autumn test than in spring test, suggesting that growth conditions and season affect infectivity and pathogenicity of PlAMV in lilies. Our study would provide important information for estimating the risk of necrotic disease caused by PlAMV, as well as for cultivation management preventing the occurrence of the disease.

Diaporthe diversity and pathogenicity revealed from a broad survey of grapevine diseases in europe
Guarnaccia, V. ; Groenewald, J.Z. ; Woodhall, J. ; Armengol, J. ; Cinelli, T. ; Eichmeier, A. ; Ezra, D. ; Fontaine, F. ; Gramaje, D. ; Gutierrez-Aguirregabiria, A. ; Kaliterna, J. ; Kiss, L. ; Larignon, P. ; Luque, J. ; Mugnai, L. ; Naor, V. ; Raposo, R. ; Sándor, E. ; Váczy, K.Z. ; Crous, P.W. - \ 2018
Persoonia 40 (2018). - ISSN 0031-5850 - p. 135 - 153.
Canker - Multi-locus sequence typing - Pathogenicity - Vitis

Species of Diaporthe are considered important plant pathogens, saprobes, and endophytes on a wide range of plant hosts. Several species are well-known on grapevines, either as agents of pre-or post-harvest infections, including Phomopsis cane and leaf spot, cane bleaching, swelling arm and trunk cankers. In this study we explore the occurrence, diversity and pathogenicity of Diaporthe spp. associated with Vitis vinifera in major grape production areas of Europe and Israel, focusing on nurseries and vineyards. Surveys were conducted in Croatia, Czech Republic, France, Hungary, Israel, Italy, Spain and the UK. A total of 175 Diaporthe strains were isolated from asymptomatic and symptomatic shoots, branches and trunks. A multi-locus phylogeny was established based on five genomic loci (ITS, tef1, cal, his3 and tub2), and the morphological characters of the isolates were determined. Preliminary pathogenicity tests were performed on green grapevine shoots with representative isolates. The most commonly isolated species were D. eres and D. ampelina. Four new Diaporthe species described here as D. bohemiae, D. celeris, D. hispaniae and D. hungariae were found associated with affected vines. Pathogenicity tests revealed D. baccae, D. celeris, D. hispaniae and D. hungariae as pathogens of grapevines. No symptoms were caused by D. bohemiae. This study represents the first report of D. ambigua and D. baccae on grapevines in Europe. The present study improves our understanding of the species associated with several disease symptoms on V. vinifera plants, and provides useful information for effective disease management.

Gram-positive bacterial extracellular vesicles and their impact on health and disease
Liu, Yue ; Defourny, Kyra A.Y. ; Smid, Eddy J. ; Abee, Tjakko - \ 2018
Frontiers in Microbiology 9 (2018)JUL. - ISSN 1664-302X
Actinobacteria - EV vaccination - Firmicutes - Membrane vesicles - Pathogenicity - Phage therapy - Probiotics

During recent years it has become increasingly clear that the release of extracellular vesicles (EVs) is a feature inherent to all cellular life forms. These lipid bilayer-enclosed particles are secreted by members of all domains of life: Eukarya, Bacteria and Archaea, being similar in size, general composition, and potency as a functional entity. Noticeably, the recent discovery of EVs derived from bacteria belonging to the Gram-positive phyla Actinobacteria and Firmicutes has added a new layer of complexity to our understanding of bacterial physiology, host interactions, and pathogenesis. Being nano-sized structures, Gram-positive EVs carry a large diversity of cargo compounds, including nucleic acids, viral particles, enzymes, and effector proteins. The diversity in cargo molecules may point to roles of EVs in bacterial competition, survival, material exchange, host immune evasion and modulation, as well as infection and invasion. Consequently, the impact of Gram-positive EVs on health and disease are being revealed gradually. These findings have opened up new leads for the development of medical advances, including strategies for vaccination and anti-bacterial treatment. The rapidly advancing research into Gram-positive EVs is currently in a crucial phase, therefore this review aims to give an overview of the groundwork that has been laid at present and to discuss implications and future challenges of this new research field.

Next generation microbiological risk assessment—Potential of omics data for hazard characterisation
Haddad, Nabila ; Johnson, Nick ; Kathariou, Sophia ; Métris, Aline ; Phister, Trevor ; Pielaat, Annemarie ; Tassou, Chrysoula ; Wells-Bennik, Marjon H.J. ; Zwietering, Marcel H. - \ 2018
International Journal of Food Microbiology 287 (2018). - ISSN 0168-1605 - p. 28 - 39.
Dose-response - Food safety - Functional genomics - Pathogenicity - Public health - Quantitative transcriptomics and proteomics - Risk analysis - Virulence
According to the World Health Organization estimates in 2015, 600 million people fall ill every year from contaminated food and 420,000 die. Microbial risk assessment (MRA) was developed as a tool to reduce and prevent risks presented by pathogens and/or their toxins. MRA is organized in four steps to analyse information and assist in both designing appropriate control options and implementation of regulatory decisions and programs. Among the four steps, hazard characterisation is performed to establish the probability and severity of a disease outcome, which is determined as function of the dose of toxin and/or pathogen ingested. This dose-response relationship is subject to both variability and uncertainty. The purpose of this review/opinion article is to discuss how Next Generation Omics can impact hazard characterisation and, more precisely, how it can improve our understanding of variability and limit the uncertainty in the dose-response relation. The expansion of omics tools (e.g. genomics, transcriptomics, proteomics and metabolomics) allows for a better understanding of pathogenicity mechanisms and virulence levels of bacterial strains. Detection and identification of virulence genes, comparative genomics, analyses of mRNA and protein levels and the development of biomarkers can help in building a mechanistic dose-response model to predict disease severity. In this respect, systems biology can help to identify critical system characteristics that confer virulence and explain variability between strains. Despite challenges in the integration of omics into risk assessment, some omics methods have already been used by regulatory agencies for hazard identification. Standardized methods, reproducibility and datasets obtained from realistic conditions remain a challenge, and are needed to improve accuracy of hazard characterisation. When these improvements are realized, they will allow the health authorities and government policy makers to prioritize hazards more accurately and thus refine surveillance programs with the collaboration of all stakeholders of the food chain.
Similar transmissibility of the Italian H7N1 highly pathogenic avian influenza virus and its low pathogenic avian influenza virus predecessor
Gonzales, Jose L. ; Koch, Guus ; Elbers, Armin R.W. ; Goot, Jeanet A. van der - \ 2018
The Veterinary Journal 232 (2018). - ISSN 1090-0233 - p. 20 - 22.
Avian influenza - Pathogenicity - Poultry - Reproduction ratio - Transmissibility
The transmissibility of the H7N1 highly pathogenic avian influenza virus (HPAIV), which caused a large epidemic in commercial poultry in Italy in 1999–2000, was studied in chickens and compared with that of the low pathogenic precursor virus (LPAIV). Group transmission experiments using the HPAIV were executed to estimate the infectious period (IP), the transmission parameter (β) and the basic reproduction number (R0). These estimates were then compared with those reported for the LPAIV. The estimated β and R0 were similar for both viruses, whilst the IP of the LPAIV was longer than that of the HPAIV. These findings indicate that transmissibility from chicken-to-chicken alone does not appear to confer an advantage for this LPAIV to evolve to a HPAIV.
Verticillium longisporum, the invisible threat to oilseed rape and other brassicaceous plant hosts
Depotter, Jasper R.L. ; Deketelaere, Silke ; Inderbitzin, Patrik ; Tiedemann, Andreas Von; Höfte, Monica ; Subbarao, Krishna V. ; Wood, Thomas A. ; Thomma, Bart P.H.J. - \ 2016
Molecular Plant Pathology 17 (2016)7. - ISSN 1464-6722 - p. 1004 - 1016.
Amphidiploid - Arabidopsis - Brassica - Disease management - Host range - Pathogenicity - Vascular wilt

Introduction: The causal agents of Verticillium wilts are globally distributed pathogens that cause significant crop losses every year. Most Verticillium wilts are caused by V. dahliae, which is pathogenic on a broad range of plant hosts, whereas other pathogenic Verticillium species have more restricted host ranges. In contrast, V. longisporum appears to prefer brassicaceous plants and poses an increasing problem to oilseed rape production. Taxonomy: Kingdom Fungi; Phylum Ascomycota; Class Sordariomycetes; Subclass Hypocreomycetida; Family Plectosphaerellaceae; genus Verticillium. Disease symptoms: Dark unilateral stripes appear on the stems of apparently healthy looking oilseed rape plants at the end of the growing season. Microsclerotia are subsequently formed in the stem cortex beneath the epidermis. Genome: Verticillium longisporum is the only non-haploid species in the Verticillium genus, as it is an amphidiploid hybrid that carries almost twice as much genetic material as the other Verticillium species as a result of interspecific hybridization. Disease management: There is no effective fungicide treatment to control Verticillium diseases, and resistance breeding is the preferred strategy for disease management. However, only a few Verticillium wilt resistance genes have been identified, and monogenic resistance against V. longisporum has not yet been found. Quantitative resistance exists mainly in the Brassica C-genome of parental cabbage lines and may be introgressed in oilseed rape breeding lines. Common name: Oilseed rape colonized by V. longisporum does not develop wilting symptoms, and therefore the common name of Verticillium wilt is unsuitable for this crop. Therefore, we propose 'Verticillium stem striping' as the common name for Verticillium infections of oilseed rape.

Bcmimp1, a Botrytis cinerea gene transiently expressed in planta, encodes a mitochondrial protein
Benito-Pescador, David ; Santander, Daniela ; Arranz, M. ; Díaz-Mínguez, José M. ; Eslava, Arturo P. ; Kan, Jan A.L. van; Benito, Ernesto P. - \ 2016
Frontiers in Microbiology 7 (2016). - ISSN 1664-302X
Botrytis cinerea - Mitochondria - Pathogenicity - Plant-pathogen interaction - ROS

Botrytis cinerea is a widespread necrotrophic fungus which infects more than 200 plant species. In an attempt to characterize the physiological status of the fungus in planta and to identify genetic factors contributing to its ability to infect the host cells, a differential gene expression analysis during the interaction B. cinerea-tomato was carried out. Gene Bcmimp1 codes for a mRNA detected by differential display in the course of this analysis. During the interaction with the host, it shows a transient expression pattern with maximal expression levels during the colonization and maceration of the infected tissues. Bioinformatic analysis suggested that BCMIMP1 is an integral membrane protein located in the mitochondrial inner membrane. Co-localization experiments with a BCMIMP1-GFP fusion protein confirmed that the protein is targeted to the mitochondria. ΔBcmimp1 mutants do not show obvious phenotypic differences during saprophytic growth and their infection ability was unaltered as compared to the wild-type. Interestingly, the mutants produced increased levels of reactive oxygen species, likely as a consequence of disturbed mitochondrial function. Although Bcmimp1 expression is enhanced in planta it cannot be considered a pathogenicity factor.

Soybean production in eastern and southern Africa and threat of yield loss due to soybean rust caused by Phakopsora pachyrhizi
Murithi, H.M. ; Beed, F. ; Tukamuhabwa, P. ; Thomma, B.P.H.J. ; Joosten, M.H.A.J. - \ 2016
Plant Pathology 65 (2016)2. - ISSN 0032-0862 - p. 176 - 188.
Control - Epidemiology - Genetic composition - Pathogenicity - Soybean demand - Virulence

Soybean is a major source of oil and proteins worldwide. The demand for soybean has increased in Africa, driven by the growing feed industry for poultry, aquaculture and home consumption in the form of processed milk, baked beans and for blending with maize and wheat flour. Soybean, in addition to being a major source of cooking oil, is also used in other industrial processes such as in the production of paints and candle wax. The demand for soybean in Africa so far outweighs the supply, hence the deficit is mainly covered through imports of soybean products such as soybean meal. The area under soybean production has increased in response to the growing demand, a trend that is expected to continue in the coming years. As the production area increases, diseases and insect pests, declining soil fertility and other abiotic factors pose a major challenge. Soybean rust disease, caused by the fungus Phakopsora pachyrhizi, presents one of the major threats to soybean production in Africa due to its rapid spread as a result of the ease by which its spores are dispersed by the wind. Disease control by introducing resistant soybean varieties has been difficult due to the presence of different populations of the fungus that vary in pathogenicity, virulence and genetic composition. Improved understanding of the dynamics of rust ecology, epidemiology and population genetics will enhance the effectiveness of targeted interventions that, in turn, will safeguard soybean productivity.

The effector repertoire of Fusarium oxysporum determines the tomato xylem proteome composition following infection
Gawehns, Fleur ; Ma, Lisong ; Bruning, Oskar ; Houterman, Petra M. ; Boeren, Sjef ; Cornelissen, B.J.C. ; Rep, Martijn ; Takken, Frank L.W. - \ 2015
Frontiers in Plant Science 6 (2015)NOVEMBER. - ISSN 1664-462X
Effectors - Label free proteomics - Pathogenicity - Virulence - Xylem sap

Plant pathogens secrete small proteins, of which some are effectors that promote infection. During colonization of the tomato xylem vessels the fungus Fusarium oxysporum f.sp. lycopersici (Fol) secretes small proteins that are referred to as SIX (Secreted In Xylem) proteins. Of these, Six1 (Avr3), Six3 (Avr2), Six5, and Six6 are required for full virulence, denoting them as effectors. To investigate their activities in the plant, the xylem sap proteome of plants inoculated with Fol wild-type or either AVR2, AVR3, SIX2, SIX5, or SIX6 knockout strains was analyzed with nano-Liquid Chromatography-Mass Spectrometry (nLC-MSMS). Compared to mock-inoculated sap 12 additional plant proteins appeared while 45 proteins were no longer detectable in the xylem sap of Fol-infected plants. Of the 285 proteins found in both uninfected and infected plants the abundance of 258 proteins changed significantly following infection. The xylem sap proteome of plants infected with four Fol effector knockout strains differed significantly from plants infected with wild-type Fol, while that of the SIX2-knockout inoculated plants remained unchanged. Besides an altered abundance of a core set of 24 differentially accumulated proteins (DAPs), each of the four effector knockout strains affected specifically the abundance of a subset of DAPs. Hence, Fol effectors have both unique and shared effects on the composition of the tomato xylem sap proteome.

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