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==Powdery mildew
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Stepwise screening of candidate antagonists for biological control of Blumeria graminis f. sp. tritici
Köhl, Jürgen ; Goossen van de Geijn, Helen ; Groenenboom de Haas, Lia ; Henken, Betty ; Hauschild, Rüdiger ; Hilscher, Ulrike ; Lombaers-van der Plas, Carin ; Bosch, Trudy van den; Wikström, Mariann - \ 2019
Biological Control 136 (2019). - ISSN 1049-9644
Antagonists - Biological control - Blumeria graminis f. sp. tritici - Powdery mildew - Risk assessment - Screening criteria - Tilletiospsis pallescens - Wheat

Antagonists for the biological control of Blumeria graminis f. sp. tritici were selected using a stepwise screening approach. Fungal colonizers of powdery mildew pustules were isolated from leaves of cereals and other plant species. Spore production, cold tolerance, drought tolerance and UV-B resistance as important characteristics for application of biocontrol candidates in the phyllosphere were tested in in vitro assays and preliminary risk assessments were conducted. Amongst 850 tested isolates 58% belonged to various taxonomical groups of Cladosporium. Only 3% belonged to species that have been reported in literature as antagonistic to powdery mildews. The stepwise screening approach allowed to reduce the number of candidate antagonists using screening criteria that can be tested reliably and cost-effectively in in vitro assays and by data mining from initially 1237 isolates down to 143 candidate antagonists belonging to 42 taxonomical groups. The potential of these isolates to reduce conidia production of B. graminis f. sp. tritici. in wheat was assessed in bioassays on potted winter wheat plants under controlled conditions. A set of ten superior isolates was subsequently tested in a series of trials on potted spring wheat plants under open field conditions. Isolates Tilletiopsis pallescens BC0441 and T. pallescens BC0850 significantly reduced the number of powdery mildew pustules per flag leaf by 30 to 62%. Slopes of the regression lines fitted to data on number of powdery mildew pustules during time were significantly reduced by the antagonists indicating that the powdery mildew epidemics were slowed down. Treatments with T. pallescens BC0441 and T. pallescens BC0850 also reduced leaf coverage with powdery mildew pustules in a small-scale field trial in spring wheat.

High resolution genetic and physical mapping of a major powdery mildew resistance locus in barley
Hoseinzadeh, Parastoo ; Zhou, Ruonan ; Mascher, Martin ; Himmelbach, Axel ; Niks, Rients E. ; Schweizer, Patrick ; Stein, Nils - \ 2019
Frontiers in Plant Science 10 (2019). - ISSN 1664-462X
Barley - High resolution mapping - Powdery mildew - Resistance locus - RLK

Powdery mildew caused by Blumeria graminis f. sp. hordei is a foliar disease with highly negative impact on yield and grain quality in barley. Thus, breeding for powdery mildew resistance is an important goal and requires constantly the discovery of new sources of natural resistance. Here, we report the high resolution genetic and physical mapping of a dominant race-specific powdery mildew resistance locus, originating from an Ethiopian spring barley accession ‘HOR2573,’ conferring resistance to several modern mildew isolates. High-resolution genetic mapping narrowed down the interval containing the resistance locus to a physical span of 850 kb. Four candidate genes with homology to known disease resistance gene families were identified. The mapped resistance locus coincides with a previously reported resistance locus from Hordeum laevigatum, suggesting allelism at the same locus in two different barley lines. Therefore, we named the newly mapped resistance locus from HOR2573 as MlLa-H. The reported co-segregating and flanking markers may provide new tools for marker-assisted selection of this resistance locus in barley breeding.

Key components of different plant defense pathways are dispensable for powdery mildew resistance of the arabidopsis mlo2 mlo6 mlo12 triple mutant
Kuhn, Hannah ; Lorek, Justine ; Kwaaitaal, Mark ; Consonni, Chiara ; Becker, Katia ; Micali, Cristina ; Themaat, Emiel Ver Loren Van; Bednarek, Paweł ; Raaymakers, Tom M. ; Appiano, Michela ; Bai, Yuling ; Feussner, Ivo - \ 2017
Frontiers in Plant Science 8 (2017). - ISSN 1664-462X
Camalexin - Indole glucosinolates - Jasmonic acid - Microarray analysis - MLO - Plant defense - Powdery mildew - Tryptophan

Loss of function mutations of particular plant MILDEW RESISTANCE LOCUS O (MLO) genes confer durable and broad-spectrum penetration resistance against powdery mildew fungi. Here, we combined genetic, transcriptomic and metabolomic analyses to explore the defense mechanisms in the fully resistant Arabidopsis thaliana mlo2 mlo6 mlo12 triple mutant. We found that this genotype unexpectedly overcomes the requirement for indolic antimicrobials and defense-related secretion, which are critical for incomplete resistance of mlo2 single mutants. Comparative microarray-based transcriptome analysis of mlo2 mlo6 mlo12 mutants and wild type plants upon Golovinomyces orontii inoculation revealed an increased and accelerated accumulation of many defense-related transcripts. Despite the biotrophic nature of the interaction, this included the non-canonical activation of a jasmonic acid/ethylene-dependent transcriptional program. In contrast to a non-adapted powdery mildew pathogen, the adapted powdery mildew fungus is able to defeat the accumulation of defense-relevant indolic metabolites in a MLO protein-dependent manner. We suggest that a broad and fast activation of immune responses in mlo2 mlo6 mlo12 plants can compensate for the lack of single or few defense pathways. In addition, our results point to a role of Arabidopsis MLO2, MLO6, and MLO12 in enabling defense suppression during invasion by adapted powdery mildew fungi.

Functional characterization of cucumber (Cucumis sativus L.) Clade V MLO genes
Berg, Jeroen A. ; Appiano, Michela ; Bijsterbosch, Gerard ; Visser, Richard G.F. ; Schouten, Henk J. ; Bai, Yuling - \ 2017
BMC Plant Biology 17 (2017)1. - ISSN 1471-2229
Cucumber (Cucumis sativus L.) - Gene expression - MLO - Powdery mildew - Susceptibility genes

Background: Powdery mildew (PM) causing fungi are well-known pathogens, infecting over 10.000 plant species, including the economically important crop cucumber (Cucumis sativus L.). Loss-of-function mutations in clade V MLO genes have previously been shown to lead to recessively inherited broad-spectrum resistance to PM in several species. In cucumber, one clade V MLO homolog (CsaMLO8) was previously identified as being a susceptibility factor to PM. Two other closely related homologs (CsaMLO1 and CsaMLO11) were found, but their function was not yet unravelled. Methods: CsaMLO1 and CsaMLO11 were cloned from cucumber and overexpressed in a tomato mlo mutant. The transcript abundances of all three CsaMLO genes in different cucumber tissues were quantified using qRT-PCR and RNA-seq, with and without inoculation with the cucumber PM fungus Podosphaera xanthii. Allelic variation of CsaMLO1 and CsaMLO11 was screened in silico in sequenced cucumber germplasm. Results: Heterologous overexpression of all three CsaMLO genes in the tomato mlo mutant restored susceptibility to PM caused by Oidium neolycopersici, albeit to a different extent: whereas overexpression of CsaMLO1 or CsaMLO8 completely restored susceptibility, overexpression of CsaMLO11 was only partially able to restore PM susceptibility. Furthermore, it was observed by qRT-PCR and RNA-seq that CsaMLO8 was significantly higher expressed in non-inoculated cucumber compared to the other two MLO genes. However, inoculation with P. xanthii led to upregulation of CsaMLO1, but not to upregulation of CsaMLO8 or CsaMLO11. Conclusions: Both CsaMLO1 and CsaMLO11 are functional susceptibility genes, although we conclude that based on the transcript abundance CsaMLO8 is probably the major clade V MLO gene in cucumber regarding providing susceptibility to PM. Potential loss-of-function mutations in CsaMLO1 and CsaMLO11 have not been identified. The generation and analysis of such mutants are interesting subjects for further investigation.

Functional characterization of the powdery mildew susceptibility gene SmMLO1 in eggplant (Solanum melongena L.)
Bracuto, Valentina ; Appiano, Michela ; Ricciardi, Luigi ; Göl, Deniz ; Visser, Richard G.F. ; Bai, Yuling ; Pavan, Stefano - \ 2017
Transgenic Research 26 (2017)3. - ISSN 0962-8819 - p. 323 - 330.
Eggplant - MLO - Plant breeding - Powdery mildew - Resistance
Eggplant (Solanum melongena L.) is one of the most important vegetables among the Solanaceae and can be a host to fungal species causing powdery mildew (PM) disease. Specific homologs of the plant Mildew Locus O (MLO) gene family are PM susceptibility factors, as their loss of function results in a recessive form of resistance known as mlo resistance. In a previous work, we isolated the eggplant MLO homolog SmMLO1. SmMLO1 is closely related to MLO susceptibility genes characterized in other plant species. However, it displays a peculiar non-synonymous substitution that leads to a T → M amino acid change at protein position 422, in correspondence of the MLO calmodulin-binding domain. In this study, we performed the functional characterization of SmMLO1. Transgenic overexpression of SmMLO1 in a tomato mlo mutant compromised resistance to the tomato PM pathogen Oidium neolycopersici, thus indicating that SmMLO1 is a PM susceptibility factor in eggplant. PM susceptibility was also restored by the transgenic expression of a synthetic gene, named s-SmMLO1, encoding a protein identical to SmMLO1, except for the presence of T at position 422. This indicates that the T → M polymorphism does not affect the protein role as PM susceptibility factor. Overall, the results of this work are of interest for the functional characterization of MLO proteins and the introduction of PM resistance in eggplant using reverse genetics.
On-farm and on-station evaluations of three orchard management approaches against apple scab and apple powdery mildew
Holb, I.J. ; Abonyi, F. ; Buurma, J. ; Heijne, B. - \ 2017
Crop Protection 97 (2017). - ISSN 0261-2194 - p. 109 - 118.
Apple scab - Fungal disease management - Integrated disease management - Malus x domestica - Pesticide risk reduction - Powdery mildew
In a three-year study (from 2012 to 2014), the efficacy of three apple management approaches (conventional, standard and advanced Integrated Pest Management - CON, IPM1 and IPM2, respectively) was aimed to investigate against apple scab and apple powdery mildew in on-station (small research scale) and on-farm (real large farm scale using existing farm equipment) experiments in order to promote practical adoption of environmentally sustainable management methods. CON used generally applied conventional pest management practices (disease/pest forecasting coupled with conventional pesticide use). IPM1 used a generally applied integrated pest management practices in most European countries (disease/pest forecasting, yellow/green-list fungicide use coupled with pruning against both diseases, yellow/green-list insecticide use coupled with mating disruption against insects). IPM2 used an advanced integration of known non-chemical practices, accepting most principles of organic farming guidelines (disease/pest forecasting, delayed fungicide applications with green-list fungicide use, pruning against both diseases coupled with orchard sanitation, biological control and mating disruption against insects). Scab and powdery mildew incidences were not significantly different between IPM1 and CON while disease incidences were significantly higher in IPM2 compared to either CON or IPM1 (P = 0.05). Overall yield was not significantly different among the three management approaches. However, the amounts of first class fruit were the highest in CON and IPM1 which were significantly higher (P = 0.05) than that of in IPM2. The amount of second class fruit was the highest in IPM2, indicating a lower fruit quality in IPM2 than in CON or IPM1. In addition, overall disease incidences and fruit quality were generally lower in the on-farm than in the on-station conditions. Our research suggested that elements of IPM1 can be easily adopted by apple growers. Despite the advanced integration of non-chemical control practices in IPM2, its future adoption will depend on the control efficacy and the economic sustainability of non-chemical control practices.
The knock-down of the expression of MdMLO19 reduces susceptibility to powdery mildew (Podosphaera leucotricha) in apple (Malus domestica)
Pessina, Stefano ; Angeli, Dario ; Martens, Stefan ; Visser, Richard G.F. ; Bai, Yuling ; Salamini, Francesco ; Velasco, Riccardo ; Schouten, Henk J. ; Malnoy, Mickael - \ 2016
Plant Biotechnology Journal 14 (2016)10. - ISSN 1467-7644 - p. 2033 - 2044.
Arabidopsis thaliana - Malus domestica - MLO - Powdery mildew - RNA interference

Varieties resistant to powdery mildew (PM; caused by Podosphaera leucotricha) are a major component of sustainable apple production. Resistance can be achieved by knocking-out susceptibility S-genes to be singled out among members of the MLO (Mildew Locus O) gene family. Candidates are MLO S-genes of phylogenetic clade V up-regulated upon PM inoculation, such as MdMLO11 and 19 (clade V) and MdMLO18 (clade VII). We report the knock-down through RNA interference of MdMLO11 and 19, as well as the complementation of resistance with MdMLO18 in the Arabidopsis thaliana triple mlo mutant Atmlo2/6/12. The knock-down of MdMLO19 reduced PM disease severity by 75%, whereas the knock-down of MdMLO11, alone or in combination with MdMLO19, did not result in any reduction or additional reduction of susceptibility compared with MdMLO19 alone. The test in A. thaliana excluded a role for MdMLO18 in PM susceptibility. Cell wall appositions (papillae) were present in both PM-resistant and PM-susceptible plants, but were larger in resistant lines. No obvious negative phenotype was observed in plants with mlo genes knocked down. Apparently, MdMLO19 plays the pivotal role in apple PM susceptibility and its knock-down induces a very significant level of resistance.

Control of powdery mildew on glasshouse-grown roses and tomatoes in the Netherlands using anhydrous milk fat and soybean oil emulsions
Wurms, K.V. ; Hofland-Zijlstra, Jantineke - \ 2015
New Zealand Plant Protection 68 (2015). - ISSN 1175-9003 - p. 380 - 388.
Anhydrous milk fat - Biopesticides - Glasshouse roses - Natural products - Powdery mildew - Soybean oil - Tomatoes

Powdery mildew (PM) is a very serious disease affecting glasshouse-grown roses and tomatoes in the Netherlands. Control is limited because of resistance to existing fungicides. Anhydrous milk fat (AMF) and soybean oil (SBO) emulsions were evaluated for control of PM in roses and tomatoes. Both AMF (14 g/litre) and SBO (14 g/litre) provided powdery mildew control on rose leaves and blooms that was significantly better (P

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