| 1. |
- Masini, Laura, et al.
(författare)
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Tolerance and overcompensation to infection by Phytophthora infestans in the wild perennial climber Solanum dulcamara
- 2019
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 9:8, s. 4557-4567
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Tidskriftsartikel (refereegranskat)abstract
- Studies of infection by Phytophthora infestans—the causal agent of potato late blight—in wild species can provide novel insights into plant defense responses, and indicate how wild plants might be influenced by recurrent epidemics in agricultural fields. In the present study, our aim was to investigate if different clones of Solanum dulcamara (a relative of potato) collected in the wild differ in resistance and tolerance to infection by a common European isolate of P. infestans. We performed infection experiments with six S. dulcamara genotypes (clones) both in the laboratory and in the field and measured the degree of infection and plant performance traits. In the laboratory, the six evaluated genotypes varied from resistant to susceptible, as measured by degree of infection 20 days post infection. Two of the four genotypes susceptible to infection showed a quadratic (concave downward) relationship between the degree of infection and shoot length, with maximum shoot length at intermediate values of infection. This result suggests overcompensation, that is, an increase in growth in infected individuals. The number of leaves decreased with increasing degree of infection, but at different rates in the four susceptible genotypes, indicating genetic variation for tolerance. In the field, the inoculated genotypes did not show any disease symptoms, but plant biomass at the end of the growing season was higher for inoculated plants than for controls, in-line with the overcompensation detected in the laboratory. We conclude that in S. dulcamara there are indications of genetic variation for both resistance and tolerance to P. infestans infection. Moreover, some genotypes displayed overcompensation. Learning about plant tolerance and overcompensation to infection by pathogens can help broaden our understanding of plant defense in natural populations and help develop more sustainable plant protection strategies for economically important crop diseases.
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| 2. |
- Grenville-Briggs, Laura J, et al.
(författare)
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Draft genome of the oomycete pathogen Phytophthora cactorum strain LV007 isolated from European beech (Fagus sylvatica)
- 2017
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Ingår i: Genomics Data. - : Elsevier. - 2213-5960. ; 12, s. 155-156
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Tidskriftsartikel (refereegranskat)abstract
- Phytophthora cactorum is a broad host range phytopathogenic oomycete. P. cactorum strain LV007 was isolated from a diseased European Beech (Fagus sylvatica) in Malmö, Sweden in 2016. The draft genome of P. cactorum strain LV007 is 67.81 Mb. It contains 15,567 contigs and 21,876 predicted protein-coding genes. As reported for other phytopathogenic Phytophthora species, cytoplasmic effector proteins including RxLR and CRN families were identified. The genome sequence has been deposited at DDBJ/ENA/GenBank under the accession NBIJ00000000. The version described in this paper is version NBIJ01000000.
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| 3. |
- Kushwaha, Sandeep Kumar, et al.
(författare)
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Draft Genome Sequence of the Mycoparasitic Oomycete Pythium oligandrum Strain CBS 530.74
- 2017
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Ingår i: Genome Announcements. - 2169-8287. ; 5
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The oomycete Pythium oligandrum is a mycoparasite and licenced biological control agent. Here, we report the draft genome sequence of P. oligandrum strain CBS 530.74, which is 36.80 Mb. It contains 341 scaffolds and 11,647 predicted protein-coding genes. As reported for plant-pathogenic Pythium species, RXLR-type effector sequences are absent.
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| 4. |
- Lankinen, Åsa, et al.
(författare)
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Challenges and opportunities for increasing the use of low-risk plant protection products in sustainable production. A review
- 2024
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Ingår i: Agronomy for Sustainable Development. - : Springer. - 1774-0746 .- 1773-0155. ; 44:2
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Forskningsöversikt (refereegranskat)abstract
- Plant production systems worldwide are struggling to meet the diverse and increasing needs of humankind while also facing challenges such as climate change and biodiversity loss. This, combined with the desirable transition from the use of conventional pesticides to more sustainable plant protection solutions, has led to an urgent, and increasing, need for low-risk plant protection products (PPPs) to be developed, applied, and integrated into management practices across all types of plant production systems. Despite a high demand from end users and consumers together with joint political goals at the EU level to replace conventional pesticides, the number of low-risk PPPs on the European market remains low, in comparison to synthetic agrochemicals. In this review, we summarize knowledge about the policy, technical, and administrative issues hampering the process of bringing new low-risk PPPs to the European market. We present an overview of the challenges in using the low-risk PPPs that are currently available within the EU agricultural, horticultural, and forestry sectors. We describe the variation in modes of action and the limitations associated with different application techniques and give concrete examples of problems and solutions from Swedish plant production sectors, in contrast to global perspectives as demonstrated by examples from African agriculture. Finally, we conclude that trans-sectoral, multi-actor approaches are required and provide suggestions on how to address the remaining knowledge gaps related to efficiency, application, and economics of low-risk PPP use in Integrated Pest Management (IPM) solutions for plant protection to improve future food security in Europe.
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| 5. |
- Lehsten, Veiko, et al.
(författare)
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Earlier occurrence and increased explanatory power of climate for the first incidence of potato late blight caused by Phytophthora infestans in Fennoscandia
- 2017
-
Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 12:5
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Tidskriftsartikel (refereegranskat)abstract
- Background Late blight (caused by Phytophthora infestans) is a devastating potato disease that has been found to occur earlier in the season over the last decades in Fennoscandia. Up until now the reasons for this change have not been investigated. Possible explanations for this change are climate alterations, changes in potato production or changes in pathogen biology, such as increased fitness or changes in gene flow within P. infestans populations. The first incidence of late blight is of high economic importance since fungicidal applications should be typically applied two weeks before the first signs of late blight and are repeated on average once a week. We use field observations of first incidence of late blight in experimental potato fields from five sites in Sweden and Finland covering a total of 30 years and investigate whether the earlier incidence of late blight can be related to the climate. We linked the field data to meteorological data and found that the previous assumption, used in common late blight models, that the disease only develops at relative humidity levels above 90% had to be rejected. Rather than the typically assumed threshold relationship between late blight disease development and relative humidity we found a linear relationship. Our model furthermore showed two distinct responses of late blight to climate. At the beginning of the observation time (in Sweden until the early 90s and in Finland until the 2000s) the link between climate and first incidence was very weak. However, for the remainder of the time period the link was highly significant, indicating a change in the biological properties of the pathogen which could for example be a change in the dominating reproduction mode or a physiological change in the response of the pathogen to climate. The study shows that models used in decision support systems need to be checked and re parametrized regularly to be able to capture changes in pathogen biology. While this study was performed with data from Fennoscandia this new pathogen biology and late blight might spread to (or already be present at) other parts of the world as well. The strong link between climate and first incidence together with the presented model offers a tool to assess late blight incidence in future climates.
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| 6. |
- Ramesh, Vetukuri, et al.
(författare)
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Draft Genome Sequence for the Tree Pathogen Phytophthora plurivora
- 2018
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Ingår i: Genome Biology and Evolution. - : Oxford University Press (OUP). - 1759-6653. ; 10:9, s. 2432-2442
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Tidskriftsartikel (refereegranskat)abstract
- Species from the genus Phytophthora are well represented among organisms causing serious diseases on trees. Phytophthora plurivora has been implicated in long-term decline of woodland trees across Europe. Here we present a draft genome sequence of P. plurivora, originally isolated from diseased European beech (Fagus sylvatica) in Malmö, Sweden. When compared with other sequenced Phytophthora species, the P. plurivora genome assembly is relatively compact, spanning 41 Mb. This is organized in 1,919 contigs and 1,898 scaffolds, encompassing 11,741 predicted genes, and has a repeat content of approximately 15%. Comparison of allele frequencies revealed evidence for tetraploidy in the sequenced isolate. As in other sequenced Phytophthora species, P. plurivora possesses genes for pathogenicity-associated RXLR and Crinkle and Necrosis effectors, predominantly located in gene-sparse genomic regions. Comparison of the P. plurivora RXLR effectors with orthologs in other sequenced species in the same clade (Phytophthora multivora and Phytophthora capsici) revealed that the orthologs were likely to be under neutral or purifying selection.
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| 7. |
- Resjö, Svante, et al.
(författare)
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Proteomic analysis of phytophthora infestans reveals the importance of cell wall proteins in pathogenicity
- 2017
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Ingår i: Molecular and Cellular Proteomics. - 1535-9476 .- 1535-9484. ; 16:11, s. 1958-1971
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Tidskriftsartikel (refereegranskat)abstract
- The oomycete Phytophthora infestans is the most harmful pathogen of potato. It causes the disease late blight, which generates increased yearly costs of up to one billion euro in the EU alone and is difficult to control. We have performed a large-scale quantitative proteomics study of six P. infestans life stages with the aim to identify proteins that change in abundance during development, with a focus on preinfectious life stages. Over 10 000 peptides from 2061 proteins were analyzed. We identified several abundance profiles of proteins that were up- or downregulated in different combinations of life stages. One of these profiles contained 59 proteins that were more abundant in germinated cysts and appressoria. A large majority of these proteins were not previously recognized as being appressorial proteins or involved in the infection process. Among those are proteins with putative roles in transport, amino acid metabolism, pathogenicity (including one RXLR effector) and cell wall structure modification. We analyzed the expression of the genes encoding nine of these proteins using RT-qPCR and found an increase in transcript levels during disease progression, in agreement with the hypothesis that these proteins are important in early infection. Among the nine proteins was a group involved in cell wall structure modification and adhesion, including three closely related, uncharacterized proteins encoded by PITG-01131, PITG-01132, and PITG-16135, here denoted Piacwp1-3. Transient silencing of these genes resulted in reduced severity of infection, indicating that these proteins are important for pathogenicity. Our results contribute to further insight into P. infestans biology, and indicate processes that might be relevant for the pathogen while preparing for host cell penetration and during infection. The mass spectrometry data have been deposited to ProteomeXchange via the PRIDE partner repository with the data set identifier PXD002446.
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| 8. |
- Haas, Brian J., et al.
(författare)
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Genome sequence and analysis of the Irish potato famine pathogen Phytophthora infestans
- 2009
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 461:7262, s. 393-398
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Tidskriftsartikel (refereegranskat)abstract
- Phytophthora infestans is the most destructive pathogen of potato and a model organism for the oomycetes, a distinct lineage of fungus-like eukaryotes that are related to organisms such as brown algae and diatoms. As the agent of the Irish potato famine in the mid-nineteenth century, P. infestans has had a tremendous effect on human history, resulting in famine and population displacement(1). To this day, it affects world agriculture by causing the most destructive disease of potato, the fourth largest food crop and a critical alternative to the major cereal crops for feeding the world's population(1). Current annual worldwide potato crop losses due to late blight are conservatively estimated at $6.7 billion(2). Management of this devastating pathogen is challenged by its remarkable speed of adaptation to control strategies such as genetically resistant cultivars(3,4). Here we report the sequence of the P. infestans genome, which at similar to 240 megabases (Mb) is by far the largest and most complex genome sequenced so far in the chromalveolates. Its expansion results from a proliferation of repetitive DNA accounting for similar to 74% of the genome. Comparison with two other Phytophthora genomes showed rapid turnover and extensive expansion of specific families of secreted disease effector proteins, including many genes that are induced during infection or are predicted to have activities that alter host physiology. These fast-evolving effector genes are localized to highly dynamic and expanded regions of the P. infestans genome. This probably plays a crucial part in the rapid adaptability of the pathogen to host plants and underpins its evolutionary potential.
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| 9. |
- Ramesh, Vetukuri, et al.
(författare)
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The presence of Phytophthora infestans in the rhizosphere of a wild Solanum species may contribute to off-season survival and pathogenicity
- 2020
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393 .- 1873-0272. ; 148
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Tidskriftsartikel (refereegranskat)abstract
- We evaluated oomycete presence and abundance in the rhizosphere of wild perennial Solarium species to investigate the presence of plant pathogenic or mycoparasitic species. Furthermore, we investigated whether these plant species could function as hosts, or associated plants, for off-season survival of economically important pathogens. We collected soil samples in Sweden from Solarium dulcamara and as a control from Vitis vinifera over all four seasons of a year, and in New Zealand from Solarium nigrum and Solarium laciniatum in the summer. Species identification, confirmed by ITS and Cox2 sequencing, and root infection assays on the crop plant Solarium tuberosum and on S. dulcamara, suggested the presence of mainly Pythiales species. In Sweden, we also found evidence for the presence of Phytophthora infestans, the causal agent of potato late blight, in the rhizosphere of S. dulcamara. These Ph. infestans isolates had no negative effects on root growth of S. dulcamara in Sweden, but were more pathogenic on potato leaves than a common lab strain. Oomycete diversity measures indicated a high similarly between seasons and countries. In conclusion, our study suggests a previously unknown overwintering strategy for the pathogen Ph. infestans, indicating a possible influence of the wild species S. dulcamara on the epidemiology of potato late blight in Sweden.
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| 10. |
- Andersen, Christian B., et al.
(författare)
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Pythium oligandrum induces growth promotion in starch potato without significantly altering the rhizosphere microbiome
- 2024
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Ingår i: Applied Soil Ecology. - 0929-1393. ; 199
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Tidskriftsartikel (refereegranskat)abstract
- Plant health promoting organisms, including microbial biological control agents, are of increasing importance for the development of more sustainable agriculture. To understand the function of these microbes as biological control agents under field conditions and their overall impact on soil and plant health, we need to learn more about the impact of plant beneficial microbes on the rhizosphere microbiome of crops such as potato. The plant beneficial oomycete Pythium oligandrum has previously been reported both as a biocontrol agent and as a plant growth promoter, or biostimulant, in several crop species. To investigate the potential of P. oligandrum as a biostimulant in potato, we performed a series of controlled-environment bioassays in three cultivars. We showed that biostimulation of potato by P. oligandrum is plant genotype-specific. We confirmed the biostimulation by P. oligandrum in the starch potato cultivar Kuras under field conditions. We further investigated the effects of P. oligandrum on the potato rhizosphere microbiome, sampling individual potato plants at three time points over the growing season (representing the vegetative growth phase, flowering, and the onset of senescence). Metabarcoding using ITS and 16S amplicon sequencing revealed no significant overall effect of P. oligandrum application on the bacterial and fungal rhizosphere communities. However, some genera were significantly differentially abundant after P. oligandrum application, including some classified as plant-beneficial microbes. We conclude that P. oligandrum has a cultivar-dependent growth-promoting effect in potato and only minor effects on the rhizosphere microbiome.
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| 11. |
- Brouwer, Sophie, et al.
(författare)
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Transcriptome Analysis of Potato Infected with the Necrotrophic Pathogen Alternaria solani
- 2021
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Ingår i: Plants. - : MDPI AG. - 2223-7747. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Potato early blight is caused by the necrotrophic fungus Alternaria solani and can result in yield losses of up to 50% if left uncontrolled. At present, the disease is controlled by chemical fungicides, yet rapid development of fungicide resistance renders current control strategies unsustainable. On top of that, a lack of understanding of potato defences and the quantitative nature of resistance mechanisms against early blight hinders the development of more sustainable control methods. Necrotrophic pathogens, compared to biotrophs, pose an extra challenge to the plant, since common defence strategies to biotic stresses such as the hypersensitive response and programmed cell death are often beneficial for necrotrophs. With the aim of unravelling plant responses to both the early infection stages (i.e., before necrosis), such as appressorium formation and penetration, as well as to later responses to the onset of necrosis, we present here a transcriptome analysis of potato interactions with A. solani from 1 h after inoculation when the conidia have just commenced germination, to 48 h post inoculation when multiple cell necrosis has begun. Potato transcripts with putative functions related to biotic stress tolerance and defence against pathogens were upregulated, including a putative Nudix hydrolase that may play a role in defence against oxidative stress. A. solani transcripts encoding putative pathogenicity factors, such as cell wall degrading enzymes and metabolic processes that may be important for infection. We therefore identified the differential expression of several potato and A. solani transcripts that present a group of valuable candidates for further studies into their roles in immunity or disease development.
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| 12. |
- Brouwer, Sophie, et al.
(författare)
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Visualising the ionome in resistant and susceptible plant-pathogen interactions
- 2021
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Ingår i: Plant Journal. - : Wiley. - 0960-7412 .- 1365-313X. ; 108, s. 870-885
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Tidskriftsartikel (refereegranskat)abstract
- At the morphological and anatomical levels, the ionome, or the elemental composition of an organism, is an understudied area of plant biology. In particular, the ionomic responses of plant-pathogen interactions are scarcely described, and there are no studies on immune reactions. In this study we explored two X-ray fluorescence (XRF)-based ionome visualisation methods (benchtop- and synchrotron-based micro-XRF [mu XRF]), as well as the quantitative inductively coupled plasma optical emission spectroscopy (ICP-OES) method, to investigate the changes that occur in the ionome of compatible and incompatible plant-pathogen interactions. We utilised the agronomically important and comprehensively studied interaction between potato (Solanum tuberosum) and the late blight oomycete pathogen Phytophthora infestans as an example. We used one late blight-susceptible potato cultivar and two resistant transgenic plant lines (only differing from the susceptible cultivar in one or three resistance genes) both in control and P. infestans-inoculated conditions. In the lesions from the compatible interaction, we observed rearrangements of several elements, including a decrease of the mobile macronutrient potassium (K) and an increase in iron (Fe) and manganese (Mn), compared with the tissue outside the lesion. Interestingly, we observed distinctly different distribution patterns of accumulation at the site of inoculation in the resistant lines for calcium (Ca), magnesium (Mg), Mn and silicon (Si) compared to the susceptible cultivar. The results reveal different ionomes in diseased plants compared to resistant plants. Our results demonstrate a technical advance and pave the way for deeper studies of the plant-pathogen ionome in the future.
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| 13. |
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| 14. |
- Burra, Dharani, et al.
(författare)
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RNAseq and Proteomics for Analysing Complex Oomycete Plant Interactions
- 2016
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Ingår i: Current Issues in Molecular Biology. - : MDPI AG. - 1467-3037 .- 1467-3045. ; 19, s. 73-87
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Forskningsöversikt (refereegranskat)abstract
- The oomycetes include some of the most devastating plant pathogens. In this review we discuss the latest results from oomycete and plant studies with emphasis on interaction studies. We focus on the outcomes of RNAseq and proteomics studies and some pitfalls of these approaches. Both pathogenic interactions and biological control are discussed. We underline the usefulness of studies at several levels of complexity from studies of one organism, up to two or more and within agricultural fields (managed settings) up to wild ecosystems. Finally we identify areas of future interest such as detailed interactome studies, dual RNAseq studies, peptide modification studies and population/meta omics with or without biological control agents.
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| 15. |
- Grenville-Briggs Didymus, Laura, et al.
(författare)
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Altitudinal Heterogeneity of UV Adaptation in Phytophthora infestans Is Associated with the Spatial Distribution of a DNA Repair Gene
- 2021
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Ingår i: Journal of Fungi. - : MDPI AG. - 2309-608X. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Climate change is considered a major threat to society and nature. UV irradiation is the most important environmental genotoxic agent. Thus, how elevated UV irradiation may influence human health and ecosystems has generated wide concern in the scientific community, as well as with policy makers and the public in general. In this study, we investigated patterns and mechanisms of UV adaptation in natural ecosystems by studying a gene-specific variation in the potato late blight pathogen, Phytophthora infestans. We compared the sequence characteristics of radiation sensitive 23 (RAD23), a gene involved in the nucleotide excision repair (NER) pathway and UV tolerance, in P. infestans isolates sampled from various altitudes. We found that lower genetic variation in the RAD23 gene was caused by natural selection. The hypothesis that UV irradiation drives this selection was supported by strong correlations between the genomic characteristics and altitudinal origin (historic UV irradiation) of the RAD23 sequences with UV tolerance of the P. infestans isolates. These results indicate that the RAD23 gene plays an important role in the adaptation of P. infestans to UV stress. We also found that different climatic factors could work synergistically to determine the evolutionary adaptation of species, making the influence of climate change on ecological functions and resilience more difficult to predict. Future attention should aim at understanding the collective impact generated by simultaneous change in several climate factors on species adaptation and ecological sustainability, using state of the art technologies such as experimental evolution, genome-wide scanning, and proteomics.
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| 16. |
- Grenville-Briggs Didymus, Laura
(författare)
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Comparative mitochondrial genome analysis of Pythium insidiosum and related oomycete species provides new insights into genetic variation and phylogenetic relationships
- 2016
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Ingår i: Gene. - : Elsevier BV. - 0378-1119 .- 1879-0038. ; 575, s. 34-41
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Tidskriftsartikel (refereegranskat)abstract
- Oomycetes are eukaryotic microorganisms, which are phylogenetically distinct from the true-fungi, which they resemble morphologically. While many oomycetes are pathogenic to plants, Pythium insidiosum is capable of infecting humans and animals. Mitochondrial (mt) genomes are valuable genetic resources for exploring the evolution of eukaryotes. During the course of 454-based nuclear genome sequencing, we identified a complete 54.9 kb mt genome sequence, containing 2 large inverted repeats, from P. insidiosum. It contains 65 different genes (including 2 ribosomal RNA genes, 25 transfer RNA genes and 38 genes encoding NADH dehydrogenases, cytochrome b, cytochrome c oxidases, ATP synthases, and ribosomal proteins). Thirty-nine of the 65 genes have two copies, giving a total of 104 genes. A set of 30 conserved protein-coding genes from the mt genomes of P. insidiosum,11 other oomycetes, and 2 diatoms (outgroup) were used for phylogenetic analyses. The oomycetes can be classified into 2 phylogenetic groups, in relation to their taxonomic lineages: Saprolegnialean and Peronosporalean. P. insidiosum is more closely related to Pythium ultimum than other oomycetes. In conclusion, the complete mt genome of P. insidiosum was successfully sequenced, assembled, and annotated, providing a useful genetic resource for exploring the biology and evolution of P. insidiosum and other oomycetes. (C) 2015 Elsevier B.V. All rights reserved.
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| 17. |
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| 18. |
- Grenville-Briggs Didymus, Laura
(författare)
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Infection mechanisms and putative effector repertoire of the mosquito pathogenic oomycete Pythium guiyangense uncovered by genomic analysis
- 2019
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Ingår i: PLoS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Pythium guiyangense, an oomycete from a genus of mostly plant pathogens, is an effective biological control agent that has wide potential to manage diverse mosquitoes. However, its mosquito-killing mechanisms are almost unknown. In this study, we observed that P. guiyangense could utilize cuticle penetration and ingestion of mycelia into the digestive system to infect mosquito larvae. To explore pathogenic mechanisms, a high-quality genome sequence with 239 contigs and an N50 contig length of 1,009 kb was generated. The genome assembly is approximately 110 Mb, which is almost twice the size of other sequenced Pythium genomes. Further genome analysis suggests that P. guiyangense may arise from a hybridization of two related but distinct parental species. Phylogenetic analysis demonstrated that P. guiyangense likely evolved from common ancestors shared with plant pathogens. Comparative genome analysis coupled with transcriptome sequencing data suggested that P. guiyangense may employ multiple virulence mechanisms to infect mosquitoes, including secreted proteases and kazal-type protease inhibitors. It also shares intracellular Crinkler (CRN) effectors used by plant pathogenic oomycetes to facilitate the colonization of plant hosts. Our experimental evidence demonstrates that CRN effectors of P. guiyangense can be toxic to insect cells. The infection mechanisms and putative virulence effectors of P. guiyangense uncovered by this study provide the basis to develop improved mosquito control strategies. These data also provide useful knowledge on host adaptation and evolution of the entomopathogenic lifestyle within the oomycete lineage. A deeper understanding of the biology of P. guiyangense effectors might also be useful for management of other important agricultural pests.Author summary Utilization of biocontrol agents has emerged as a promising mosquito control strategy, and Pythium guiyangense has wide potential to manage diverse mosquitoes with high efficiency. However, the molecular mechanisms underlying pathological processes remain almost unknown. We observed that P. guiyangense invades mosquito larvae through cuticle penetration and through ingestion of mycelia via the digestive system, jointly accelerating mosquito larvae mortality. We also present a high-quality genome assembly of P. guiyangense that contains two distinct genome complements, which likely resulted from a hybridization of two parental species. Our analyses revealed expansions of kinases, proteases, kazal-type protease inhibitors, and elicitins that may be important for adaptation of P. guiyangense to a mosquito-pathogenic lifestyle. Moreover, our experimental evidence demonstrated that some Crinkler effectors of P. guiyangense can be toxic to insect cells. Our findings suggest new insights into oomycete evolution and host adaptation by animal pathogenic oomycetes. Our new genome resource will enable better understanding of infection mechanisms, with the potential to improve the biological control of mosquitoes and other agriculturally important pests.
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| 19. |
- Grenville-Briggs Didymus, Laura
(författare)
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Infection of the brown alga Ectocarpus siliculosus by the oomycete Eurychasma dicksonii induces oxidative stress and halogen metabolism
- 2016
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Ingår i: Plant, Cell and Environment. - : Wiley. - 0140-7791 .- 1365-3040. ; 39, s. 259-271
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Tidskriftsartikel (refereegranskat)abstract
- Pathogens are increasingly being recognized as key evolutionary and ecological drivers in marine ecosystems. Defence mechanisms of seaweeds, however, have mostly been investigated by mimicking infection using elicitors. We have established an experimental pathosystem between the genome brown model seaweed Ectocarpus siliculosus and the oomycete Eurychasma dicksonii as a powerful new tool to investigate algal responses to infection. Using proteomics, we identified 21 algal proteins differentially accumulated in response to Eu. dicksonii infection. These include classical algal stress response proteins such as a manganese superoxide dismutase, heat shock proteins 70 and a vanadium bromoperoxidase. Transcriptional profiling by qPCR confirmed the induction of the latter during infection. The accumulation of hydrogen peroxide was observed at different infection stages via histochemical staining. Inhibitor studies confirmed that the main source of hydrogen peroxide is superoxide converted by superoxide dismutase. Our data give an unprecedented global overview of brown algal responses to pathogen infection, and highlight the importance of oxidative stress and halogen metabolism in these interactions. This suggests overlapping defence pathways with herbivores and abiotic stresses. We also identify previously unreported actors, in particular a Rad23 and a plastid-lipid-associated protein, providing novel insights into the infection and defence processes in brown algae.
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| 20. |
- Grenville-Briggs Didymus, Laura
(författare)
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Oomycete diseases in forestry and agriculture
- 2016
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Ingår i: Scandinavian Journal of Forest Research. - 0282-7581 .- 1651-1891. ; 31, s. 235-235
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 21. |
- Grenville-Briggs Didymus, Laura
(författare)
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What are the Top 10 Unanswered Questions in Molecular Plant-Microbe Interactions?
- 2020
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Ingår i: Molecular plant-microbe interactions. - 0894-0282 .- 1943-7706. ; 33, s. 1354-1365
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Forskningsöversikt (refereegranskat)abstract
- The past few decades have seen major discoveries in the field of molecular plant-microbe interactions. As the result of technological and intellectual advances, we are now able to answer questions at a level of mechanistic detail that we could not have imagined possible 20 years ago. The MPMI Editorial Board felt it was time to take stock and reassess. What big questions remain unanswered? We knew that to identify the fundamental, overarching questions that drive our research, we needed to do this as a community. To reach a diverse audience of people with different backgrounds and perspectives, working in different areas of plant-microbe interactions, we queried the more than 1,400 participants at the 2019 International Congress on Molecular Plant-Microbe Interactions meeting in Glasgow. This group effort resulted in a list of ten, broad-reaching, fundamental questions that influence and inform our research. Here, we introduce these Top 10 unanswered questions, giving context and a brief description of the issues. Each of these questions will be the subject of a detailed review in the coming months. We hope that this process of reflecting on what is known and unknown and identifying the themes that underlie our research will provide a framework to use going forward, giving newcomers a sense of the mystery of the big questions and inspiring new avenues and novel insights.
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| 22. |
- Grenville-Briggs, Laura J., et al.
(författare)
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A family of small tyrosine rich proteins is essential for oogonial and oospore cell wall development of the mycoparasitic oomycete Pythium oligandrum
- 2013
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Ingår i: Fungal Biology. - : Elsevier BV. - 1878-6146 .- 1878-6162. ; 117:3, s. 163-172
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Tidskriftsartikel (refereegranskat)abstract
- The mycoparasitic oomycete Pythium oligandrum is homothallic, producing an abundance of thick-walled spiny oospores in culture. After mining a cDNA sequence dataset, we identified a family of genes that code for small tyrosine rich (Pythium oligandrum small tyrosine rich (PoStr)) proteins. Sequence analysis identified similarity between the PoStr proteins and putative glycine-rich cell wall proteins from the related plant pathogenic oomycete Pythium ultimum, and mating-induced genes from the oomycete Phytophthora infestans. Expression analysis showed that PoStr transcripts accumulate during oospore production in culture and immunolocalisation indicates the presence of these proteins in oogonial and oospore cell walls. PoStr protein abundance correlated positively with production of oogonia as determined by antibiotic-mediated oogonia suppression. To further characterise the role of PoStr proteins in P. oligandrum oospore production, we silenced this gene family using homology-dependent gene silencing. This represents the first characterisation of genes using gene silencing in a Pythium species. Oospores from silenced strains displayed major ultrastructural changes and were sensitive to degradative enzyme treatment. Oogonia of silenced strains either appeared to be arrested at the mature oosphere stage of development or in around 40 % of the structures, showed a complete suppression of oospore formation. Suppressed oogonia were highly vacuolated and the oogonium wall was thickened by a new inner wall layer. Our data suggest PoStr proteins are probably integral structural components of the normal oospore cell wall and play a key role in oospore formation.
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| 23. |
- Grenville-Briggs, Laura J., et al.
(författare)
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A Molecular Insight into Algal-Oomycete Warfare : cDNAAnalysis of Ectocarpus siliculosus Infected with the BasalOomycete Eurychasma dicksonii
- 2011
-
Ingår i: PLOS ONE. - : PUBLIC LIBRARY SCIENCE. - 1932-6203. ; 6:9, s. e24500-
-
Tidskriftsartikel (refereegranskat)abstract
- Brown algae are the predominant primary producers in coastal habitats, and like land plants are subject to disease and parasitism. Eurychasma dicksonii is an abundant, and probably cosmopolitan, obligate biotrophic oomycete pathogen of marine brown algae. Oomycetes (or water moulds) are pathogenic or saprophytic non-photosynthetic Stramenopiles, mostly known for causing devastating agricultural and aquacultural diseases. Whilst molecular knowledge is restricted to crop pathogens, pathogenic oomycetes actually infect hosts from most eukaryotic lineages. Molecular evidence indicates that Eu. dicksonii belongs to the most early-branching oomycete clade known so far. Therefore Eu. dicksonii is of considerable interest due to its presumed environmental impact and phylogenetic position. Here we report the first large scale functional molecular data acquired on the most basal oomycete to date. 9873 unigenes, totalling over 3.5Mb of sequence data, were produced from Sanger-sequenced and pyrosequenced EST libraries of infected Ectocarpus siliculosus. 6787 unigenes (70%) were of algal origin, and 3086 (30%) oomycete origin. 57% of Eu. dicksonii sequences had no similarity to published sequence data, indicating that this dataset is largely unique. We were unable to positively identify sequences belonging to the RXLR and CRN groups of oomycete effectors identified in higher oomycetes, however we uncovered other unique pathogenicity factors. These included putative algal cell wall degrading enzymes, cell surface proteins, and cyclophilin-like proteins. A first look at the host response to infection has also revealed movement of the host nucleus to the site of infection as well as expression of genes responsible for strengthening the cell wall, and secretion of proteins such as protease inhibitors. We also found evidence of transcriptional reprogramming of E. siliculosus transposable elements and of a viral gene inserted in the host genome.
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| 24. |
- Grenville-Briggs, Laura J., et al.
(författare)
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Cellulose synthesis in Phytophthora infestans is required for normal appressorium formation and successful infection of potato
- 2008
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Ingår i: The Plant Cell. - : Oxford University Press (OUP). - 1040-4651 .- 1532-298X. ; 20:3, s. 720-738
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose, the important structural compound of cell walls, provides strength and rigidity to cells of numerous organisms. Here, we functionally characterize four cellulose synthase genes (CesA) in the oomycete plant pathogen Phytophthora infestans, the causal agent of potato (Solanum tuberosum) late blight. Three members of this new protein family contain Pleckstrin homology domains and form a distinct phylogenetic group most closely related to the cellulose synthases of cyanobacteria. Expression of all four genes is coordinately upregulated during pre- and early infection stages of potato. Inhibition of cellulose synthesis by 2,6-dichlorobenzonitrile leads to a dramatic reduction in the number of normal germ tubes with appressoria, severe disruption of the cell wall in the preinfection structures, and a complete loss of pathogenicity. Silencing of the entire gene family in P. infestans with RNA interference leads to a similar disruption of the cell wall surrounding appressoria and an inability to form typical functional appressoria. In addition, the cellulose content of the cell walls of the silenced lines is >50% lower than in the walls of the nonsilenced lines. Our data demonstrate that the isolated genes are involved in cellulose biosynthesis and that cellulose synthesis is essential for infection by P. infestans.
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| 25. |
- Grenville-Briggs, Laura J., et al.
(författare)
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Self-directed student research through analysis of microarray datasets: a computer-based functional genomics practical class for Masters-level students
- 2011
-
Ingår i: Biochemistry and molecular biology education. - : Wiley. - 1470-8175 .- 1539-3429. ; 39:6, s. 440-447
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Tidskriftsartikel (refereegranskat)abstract
- This report describes a linked series of Masters-level computer practical workshops. They comprise an advanced functional genomics investigation, based upon analysis of a microarray dataset probing yeast DNA damage responses. The workshops require the students to analyse highly complex transcriptomics datasets, and were designed to stimulate active learning through experience of current research methods in bioinformatics and functional genomics. They seek to closely mimic a realistic research environment, and require the students first to propose research hypotheses, then test those hypotheses using specific sections of the microarray dataset. The complexity of the microarray data provides students with the freedom to propose their own unique hypotheses, tested using appropriate sections of the microarray data. This research latitude was highly regarded by students and is a strength of this practical. In addition, the focus on DNA damage by radiation and mutagenic chemicals allows them to place their results in a human medical context, and successfully sparks broad interest in the subject material. In evaluation, 79% of students scored the practical workshops on a five-point scale as 4 or 5 (totally effective) for student learning. More broadly, the general use of microarray data as a student research playground is also discussed.
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| 26. |
- Jiang, Rays H. Y., et al.
(författare)
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Distinctive Expansion of Potential Virulence Genes in the Genome of the Oomycete Fish Pathogen Saprolegnia parasitica
- 2013
-
Ingår i: PLOS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 9:6, s. e1003272-
-
Tidskriftsartikel (refereegranskat)abstract
- Oomycetes in the class Saprolegniomycetidae of the Eukaryotic kingdom Stramenopila have evolved as severe pathogens of amphibians, crustaceans, fish and insects, resulting in major losses in aquaculture and damage to aquatic ecosystems. We have sequenced the 63 Mb genome of the fresh water fish pathogen, Saprolegnia parasitica. Approximately 1/3 of the assembled genome exhibits loss of heterozygosity, indicating an efficient mechanism for revealing new variation. Comparison of S. parasitica with plant pathogenic oomycetes suggests that during evolution the host cellular environment has driven distinct patterns of gene expansion and loss in the genomes of plant and animal pathogens. S. parasitica possesses one of the largest repertoires of proteases (270) among eukaryotes that are deployed in waves at different points during infection as determined from RNA-Seq data. In contrast, despite being capable of living saprotrophically, parasitism has led to loss of inorganic nitrogen and sulfur assimilation pathways, strikingly similar to losses in obligate plant pathogenic oomycetes and fungi. The large gene families that are hallmarks of plant pathogenic oomycetes such as Phytophthora appear to be lacking in S. parasitica, including those encoding RXLR effectors, Crinkler's, and Necrosis Inducing-Like Proteins (NLP). S. parasitica also has a very large kinome of 543 kinases, 10% of which is induced upon infection. Moreover, S. parasitica encodes several genes typical of animals or animal-pathogens and lacking from other oomycetes, including disintegrins and galactose-binding lectins, whose expression and evolutionary origins implicate horizontal gene transfer in the evolution of animal pathogenesis in S. parasitica.
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| 27. |
- Kalyandurg, Pruthvi Balachandra, et al.
(författare)
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Efficient RNA silencing suppression activity of Potato Mop-Top Virus 8K protein is driven by variability and positive selection
- 2019
-
Ingår i: Virology. - : Elsevier BV. - 0042-6822 .- 1178-122X. ; 535, s. 111-121
-
Tidskriftsartikel (refereegranskat)abstract
- Previously, we investigated the evolution of Potato mop-top virus (PMTV) ORFs. Results indicate that positive selection acts exclusively on an ORF encoding the 8K protein, a weak viral suppressor of RNA silencing (VSR). However, how the extraordinary variability contributes to 8K-mediated RNA silencing suppression remains unknown. Here, we characterized the RNA silencing suppression activity of the 8K protein from seven diverse isolates. We show that 8K encoded by isolate P1 exhibits stronger RNA silencing suppression activity than the 8K protein from six other isolates. Mutational analyses revealed that Ser-50 is critical for these differences. By comparing small RNA profiles we found a lower abundance of siRNAs with U residue at the 5'-terminus after expression of the P1 8K compared to expression of 8K from isolate P125, an isolate with weak VSR activity. These results provide new clues as to the role of positive selection in shaping activities of VSRs.
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| 28. |
- Kushwaha, Sandeep Kumar, et al.
(författare)
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Draft Genome of Biocontrol Agent Pythium periplocum Strain CBS 532.74
- 2017
-
Ingår i: Genome Announcements. - 2169-8287. ; 5
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The oomycete Pythium periplocum is an aggressive mycoparasite of a number of plant pathogenic fungi and oomycetes and therefore has potential as a biological control agent. Here, we report the first draft genome sequence of P. periplocum, which comprises 35.89 Mb. It contains 1,043 scaffolds and 14,399 predicted protein-coding genes.
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| 29. |
- Lankinen, Åsa, et al.
(författare)
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Fokusprojekt Lågriskmedel i växtskyddet
- 2019
-
Rapport (populärvet., debatt m.m.)abstract
- Fokusgruppens syfte har varit att definiera kunskapsluckor avseende den praktiska användningen och implementeringen av alternativa medel med låg risk för bekämpning av skadegörare och sjukdomar inom jordbruk, trädgårdsodling och skogsbruk. Vi har utgått från en bred definition av medel med låg risk, som har omfattat både allmänkemikalier och växtskyddsmedel med låg risk (enligt gällande EU-lagstiftning). Trots att det idag finns ett ökat behov av alternativa verktyg inom växtskyddet och politiska mål om minimerad användning av kemiska medel, så är användningen av alternativa bekämpningsmedel i fältodlade grödor mycket begränsad. • En viktig faktor som styr och begränsar tillgängligheten av alternativa medel är EU-lagstiftningen för godkännande av dessa medel. För att kunna registrera ett medel behövs en investering från det företag som ansöker om godkännande, vilket kan vara en anledning till att medel inte blir tillgängliga på marknaden. En annan lagteknisk begränsning är ogynnsamma skatteregler för dessa medel. • Från ett användarperspektiv är bristande kunskap om hur effektiva dessa medel är, hur man bäst applicerar dem samt hur de kan integreras i befintliga växtskyddsstrategier en bidragande orsak till att de inte används fullt ut. • Rådgivningen pekar också på en otydlighet om vilka medel som får användas speciellt i ekologisk produktion och att användningen missgynnas av höga priser i kombination med en osäkerhet om hur effektiva dessa medel är. • I Jordbruksverkets rapport ”Hinder för ökad användning av alternativa bekämpningsmedel” (SJV, Rapport 2019:3), som medlemmar av fokusgruppen har varit med att skriva, är ett av förslagen en utökad rådgivningsverksamhet. Detta eftersom informationsinsatser och aktiv rådgivning kan påverka hur snabbt odlare accepterar och börjar använda ett växtskyddsmedel, speciellt om det har nya egenskaper (och en ny verkningsmekanism). Forskning visar att en ny åtgärd/metod inte bara ska Sammanfattning och slutsatser 5 passa in i befintliga verksamheter utan också passa med attityd och värderingar hos användaren. • Från ett forskningsperspektiv kan vi se ett klart behov av tillämpningsnära forskning framför allt för att få en ökad kunskap om hur alternativa bekämpningsmedel kan integreras i befintliga växtskyddsstrategier. En utmaning är den begränsade mängd forskningsmedel som finns att söka för denna typ av forskning. • Forskningen är ofta väldigt uppdelad mellan agrikultur, hortikultur och skogsbruk. Här skulle man kunna dra nytta av kunskap inom respektive system eftersom vissa aspekter är generella mellan olika system, åtminstone för vissa grödor/träd. • Från ett internationellt perspektiv kan vi se vinster med ett bättre samarbete med närliggande länder, tex Plant Biologicals Network (PBN) som koordineras från Danmark, men även engagemang inom det vidare EUperspektivet (bla lagar). • Ytterligare en slutsats från fokusgruppens arbete är att växtskyddsforskningen på SLU behöver samordnas bättre, tex genom att knyta samman de kompetenscentrum som finns idag – CBC och CKB – med nya strukturer som skulle kunna fokusera på i) analys av växtskadegörare och ii) lågrisk-metoder och hur dessa kan spela en roll i integrerat växtskydd (IPM). • ygarbeta tillsammans för att få till en bra samverkan och kunskapsutbyte.
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| 30. |
- Larsson Herrera, Sebastian, et al.
(författare)
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Monitoring and discrimination of Pandemis moths in apple orchards using semiochemicals, wing pattern morphology and DNA barcoding
- 2020
-
Ingår i: Crop Protection. - : Elsevier BV. - 0261-2194 .- 1873-6904. ; 132
-
Tidskriftsartikel (refereegranskat)abstract
- Non-phemmonal insect attractants of plant and microbial origin are often classified as kairomones. They differ from moth pheromones in that they can attract both sexes of several insect species. Kairomones are nowadays the object of several studies, due to their promising properties for monitoring and selective control of agricultural pests. Here we report on field trapping experiments carried out in apple orchards to quantify the response of the two leafroller species Pandemis heparana (Denis & Schiffermuller) and Pandemis cerasana (Hubner) to potential kairomones (acetic acid (AA), 2-phenyl ethanol (2-PET), pear ester (PE) and benzyl cyanide (BC)) in apple orchards. Specimens of the two species were sexed and classified to the species level using a morphological key based on wing traits. DNA barcoding was used to validate the discrimination between the two species through the morphological key. A two-component blend of AA and 2-PET was effective in catching significant numbers of females of P. heparana and P. cerasana. The addition of PE increased male but not female catches of only P. heparana. For P. heparana blends containing AA and BC with or without PE caught significantly fewer males and females than blends with PET and the AA/BC combination was as effective as PET releasing blends in trapping P. cerasana females. Morphological identification of Pandemis by wing pattern was in agreement with the DNA barcoding in the majority of cases. Additional studies are now required to establish an economic threshold to correlate moth catches with fruit damage and to the possibility that attract and kill based on the identified kairomones can be used to reduce damage.
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| 31. |
- Liang, Dong, et al.
(författare)
-
Horizontal Gene Transfer and Tandem Duplication Shape the Unique CAZyme Complement of the Mycoparasitic Oomycetes Pythium oligandrum and Pythium periplocum
- 2020
-
Ingår i: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X. ; 11
-
Tidskriftsartikel (refereegranskat)abstract
- Crop protection strategies that are effective but that reduce our reliance on chemical pesticides are urgently needed to meet the UN sustainable development goals for global food security. Mycoparasitic oomycetes such as Pythium oligandrum and Pythium periplocum, have potential for the biological control of plant diseases that threaten crops and have attracted much attention due to their abilities to antagonize plant pathogens and modulate plant immunity. Studies of the molecular and genetic determinants of mycoparasitism in these species have been less well developed than those of their fungal counterparts. Carbohydrate-active enzymes (CAZymes) from P. oligandrum and P. periplocum are predicted to be important components of mycoparasitism, being involved in the degradation of the cell wall of their oomycete and fungal prey species. To explore the evolution of CAZymes of these species we performed an in silico identification and comparison of the full CAZyme complement (CAZyome) of the two mycoparasitic Pythium species (P. oligandrum and P. periplocum), with seven other Pythium species, and four Phytophthora species. Twenty CAZy gene families involved in the degradation of cellulose, hemicellulose, glucan, and chitin were expanded in, or unique to, mycoparasitic Pythium species and several of these genes were expressed during mycoparasitic interactions with either oomycete or fungal prey, as revealed by RNA sequencing and quantitative qRT-PCR. Genes from three of the cellulose and chitin degrading CAZy families (namely AA9, GH5_14, and GH19) were expanded via tandem duplication and predominantly located in gene sparse regions of the genome, suggesting these enzymes are putative pathogenicity factors able to undergo rapid evolution. In addition, five of the CAZy gene families were likely to have been obtained from other microbes by horizontal gene transfer events. The mycoparasitic species are able to utilize complex carbohydrates present in fungal cell walls, namely chitin and N-acetylglucosamine for growth, in contrast to their phytopathogenic counterparts. Nonetheless, a preference for the utilization of simple sugars for growth appears to be a common trait within the oomycete lineage.
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| 32. |
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| 33. |
- Löbmann, Michael, et al.
(författare)
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The occurrence of pathogen suppressive soils in Sweden in relation soil biota, soil properties, and farming practices
- 2016
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393 .- 1873-0272. ; 107, s. 57-65
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Tidskriftsartikel (refereegranskat)abstract
- Despite more than 50 years of research and their great potential for sustainable pest management, pathogen suppressive soils remain poorly understood. We conducted a study on suppression of root rot disease symptoms associated with Pythium ultimum in untreated and heat-sterilized soil from ten southern Swedish farms with six different cropping and management regimes. Physical and chemical soil properties, soil nematodes belonging to different trophic guilds, and the predominant soil oomycetes were analyzed for their potential as indicators of soil suppressiveness. Six of the ten sampled soils were suppressive to P. ultimum disease symptoms. Suppressive or conducive properties of the soils from sites with permanent soil cover were related to the presence of live soil biota, while soils from sites with interrupted soil cover had suppressive or conducive effects unrelated to live soil biota. In soils with biologically conducive effects, soils had high or low cation nutrient content, while biologically suppressive soils had intermediate nutrient levels. No relationship was found between disease symptoms and the soil nematode trophic community or the predominant soil oomycetes. Permanent soil cover and a balanced nutrient supply were correlated with biologically suppressive effects on P. ultimum disease symptoms. (C) 2016 The Authors. Published by Elsevier B.V.
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| 34. |
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| 35. |
- Mostafanezhad, Hadis, et al.
(författare)
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Rapid emergence of boscalid resistance in Swedish populations of Alternaria solani revealed by a combination of field and laboratory experiments
- 2022
-
Ingår i: European Journal of Plant Pathology. - : Springer Science and Business Media LLC. - 0929-1873 .- 1573-8469. ; 162, s. 289-303
-
Tidskriftsartikel (refereegranskat)abstract
- Early blight, caused by Alternaria solani, is a common potato disease worldwide. Reduced field efficacy of the fungicide boscalid against this disease has been reported in several countries. Boscalid resistance has been mostly studied with in-vitro and/or greenhouse experiments. Field studies validating this phenomenon are largely missing. Here, for the first time in Scandinavia, we validated boscalid resistance in a Swedish population of A. solani both in the field and in the laboratory. Field trials between 2014 and 2017 in Nymo showed significant efficacy reduction by year. The target regions of the A. solani genes encoding the succinate dehydrogenase subunits (Sdh) B, C and D of samples collected from Nymo, and additional fields in south-eastern and central Sweden, were analysed for substitutions associated with loss of boscalid sensitivity. In 2014, the SdhC-H134R mutation was found at several sites at a low frequency, while, in 2017, the majority of the samples had either the SdhB-H278Y or the SdhC-H134R substitution. No mutations were detected in the gene encoding the SdhD subunit. Spore germination tests showed a high sensitivity (EC50 < 1 mu g mL(-1)) of isolates lacking the substitutions. This was supported by a significant decrease in their radial growth rate, from 0.1 to 10 mu g mL(-1) boscalid. However, the mutated isolates had EC50 > 100 mu g mL(-1) and their growth rates hardly decreased at concentrations above 1-10 mu g mL(-1). These results add to the current knowledge of fungicide resistance development in field and indicate that early blight management in southeast Sweden should no longer rely on boscalid.
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| 36. |
- Odilbekov, Firuz, et al.
(författare)
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Intact salicylic acid signalling is required for potato defence against the necrotrophic fungus Alternaria solani
- 2020
-
Ingår i: Plant Molecular Biology. - : Springer Science and Business Media LLC. - 0167-4412 .- 1573-5028. ; 104, s. 1-19
-
Tidskriftsartikel (refereegranskat)abstract
- Key Message Using disease bioassays and transcriptomic analysis we show that intact SA-signalling is required for potato defences against the necrotrophic fungal pathogenAlternaria solani. Early blight, caused by the necrotrophic fungusAlternaria solani,is an increasing problem in potato cultivation. Studies of the molecular components defining defence responses toA. solaniin potato are limited. Here, we investigate plant defence signalling with a focus on salicylic acid (SA) and jasmonic acid (JA) pathways in response toA. solani. Our bioassays revealed that SA is necessary to restrict pathogen growth and early blight symptom development in both potato foliage and tubers. This result is in contrast to the documented minimal role of SA in resistance ofArabidopsis thalianaagainst necrotrophic pathogens. We also present transcriptomic analysis with 36 arrays ofA. solaniinoculated SA-deficient, JA-insensitive, and wild type plant lines. A greater number of genes are differentially expressed in the SA-deficient mutant plant line compared to the wild type and JA- insensitive line. In wild type plants, genes encoding metal ion transporters, such as copper, iron and zinc transporters were upregulated and transferase-encoding genes, for example UDP-glucoronosyltransferase and Serine-glyoxylate transferase, were downregulated. The SA-deficient plants show upregulation of genes enriched in GO terms related to oxidoreductase activity, respiratory chain and other mitochondrial-related processes.Pathogenesis-relatedgenes, such as genes encoding chitinases and PR1, are upregulated in both the SA-deficient and wild type plants, but not in the JA-insensitive mutants. The combination of our bioassays and the transcriptomic analysis indicate that intact SA signalling, and not JA signalling, is required for potato defences against the necrotrophic pathogenA. solani.
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| 37. |
- Ramesh, Vetukuri, et al.
(författare)
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Effect of RNA silencing suppression activity of chrysanthemum virus B p12 protein on small RNA species
- 2020
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Ingår i: Archives of Virology. - : Springer Science and Business Media LLC. - 0304-8608 .- 1432-8798. ; 165, s. 2953-2959
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Tidskriftsartikel (refereegranskat)abstract
- Chrysanthemum virus B encodes a multifunctional p12 protein that acts as a transcriptional activator in the nucleus and as a suppressor of RNA silencing in the cytoplasm. Here, we investigated the impact of p12 on accumulation of major classes of small RNAs (sRNAs). The results show dramatic changes in the sRNA profiles characterised by an overall reduction in sRNA accumulation, changes in the pattern of size distribution of canonical siRNAs and in the ratio between sense and antisense strands, lower abundance of siRNAs with a U residue at the 5 '-terminus, and changes in the expression of certain miRNAs, most of which were downregulated.
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| 38. |
- Ramesh, Vetukuri, et al.
(författare)
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Genome Sequence Resource for the Oomycete Taro Pathogen Phytophthora colocasiae
- 2018
-
Ingår i: Molecular plant-microbe interactions. - 0894-0282 .- 1943-7706. ; 31, s. 903-905
-
Tidskriftsartikel (refereegranskat)abstract
- Phytophthora colocasiae is a phytopathogenic oomycete that causes leaf blight and corm rot on taro (Colocasia esculenta), an important staple crop in the tropics. The impact of P. colocasiae is a serious concern for food security in Asian and Oceanic regions. Vietnamese strain 7290 of P. colocasiae was sequenced (Illumina) to assemble a draft genome of 56.6 Mb, comprised of 19,853 scaffolds and 19,984 predicted protein-coding genes. As in other Phytophthora species, P. colocasiae possesses numerous pathogenicity-related genes, such as the RxLR class of effectors. This draft genome sequence of P. colocasiae provides a resource to underpin the first steps in determining the molecular mechanisms of disease development in this pathosystem.
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| 39. |
- Ramesh, Vetukuri, et al.
(författare)
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Phytophthora infestans effector Pi14054 is a novel candidate suppressor of host silencing mechanisms
- 2017
-
Ingår i: European Journal of Plant Pathology. - : Springer Science and Business Media LLC. - 0929-1873 .- 1573-8469. ; 149, s. 771-777
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Tidskriftsartikel (refereegranskat)abstract
- Phytophthora infestans is the oomycete pathogen responsible for the devastating late blight disease on potato and tomato. It can also infect the model solanaceous plant Nicotiana benthamiana. P. infestans secretes, and translocates into host cells, an array of RxLR class effectors potentially involved in diverse functions that facilitate infection of host plants. Intensive research efforts are currently focused on determining the role(s) of effectors in promoting late blight disease development, with many experiments carried out in the model plant N. benthamiana. In this study we demonstrate that candidate effector Pi14054 has activity as a suppressor of RNA silencing in N. benthamiana using an established reporter assay based on the Turnip crinkle virus - green fluorescent protein (TCV-sGFP) system. Pi14054 was able to complement TCV deficient for a viral suppressor of RNA silencing. This is a novel way to identify RNA silencing suppressors that potentially manipulate host immune responses. Transcripts encoding Pi14054 were most abundant during the first 36 h of infection development, suggesting that expression of this gene is specifically induced in contact with host tissue to modulate plant defences, as seen with other known effectors. Pi14054 is present in a diverse range of modern aggressive and hyper-aggressive European P. infestans isolates, suggesting a potential role for this effector in pathogenicity.
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| 40. |
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| 41. |
- Rossi, Valentina, et al.
(författare)
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Management of Aphanomyces root rot disease in sugar beet - a review
- 2022
-
Ingår i: International sugar journal. - 0020-8841. ; 124, s. 382-387
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Forskningsöversikt (refereegranskat)abstract
- Sugar beet (Beta vulgaris L.) is an important cash crop and is one of the main sources of sucrose, accounting for more than 30% of sugar production worldwide. Sugar beet production is often threatened by soil-borne pathogens, which can attack the roots at all stages of sugar beet development, disrupting entire sugar beet fields and causing severe yield losses. One of the most problematic root diseases in sugar beet is Aphanomyces root rot, caused by the oomycete Aphanomyces cochlioides. This pathogen is globally widespread and is responsible for drastic economic damage in all major sugar beet producing countries. Sources of resistance are limited, and no effective control measures are currently available. Further studies on host-pathogen interactions are needed to improve disease management, and novel breeding tools are urgently required. Moreover, the increasing knowledge of biological control agents could be employed to develop integrated disease management strategies to minimize the damage caused by A. cochlioides. In this review, we provide an overview of A. cochlioides biology and infection processes focusing on disease management and new insights for future control strategies.
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| 42. |
- Rossi, Valentina, et al.
(författare)
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Rapid detection and quantification of Aphanomyces cochlioides in sugar beet
- 2023
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Ingår i: Journal of plant pathology. - 1125-4653 .- 2239-7264. ; 105, s. 1581–1591-
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Tidskriftsartikel (refereegranskat)abstract
- Sugar beet (Beta vulgaris L.) is an economically important crop in temperate climates providing nearly 30% of sugar production worldwide. The oomycete Aphanomyces cochlioides is the causative agent of seedling damping-off and root rot disease in sugar beet. The pathogen is responsible for plant degeneration and drastic yield losses in all major sugar beet producing areas. The identification of resistant germplasm is essential to reduce the use of chemical treatments as well as the costs of protective measures and to effectively limit the damage caused by the pathogen. In this study we aimed to establish a qPCR-based method to quantify the pathogen DNA in infected plants and to predict the resistance levels of different sugar beet genotypes in response to A. cochlioides. The difference in the response to A. cochlioides isolates with different geographical origins was investigated. In addition, confocal microscopy was performed in order to observe the spatial and temporal colonization pattern in infected seedlings of susceptible and partially resistant breeding lines. The research presented in this article provides a tool to understand the progress of the infection in infected tissues and to identify the genetic background of resistance to A. cochlioides that can be used to support breeding programs.
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| 43. |
- Rur, Mira, et al.
(författare)
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Screening of alternative products for integrated pest management of cucurbit powdery mildew in Sweden
- 2018
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Ingår i: European Journal of Plant Pathology. - : Springer Science and Business Media LLC. - 0929-1873 .- 1573-8469. ; 150, s. 127-138
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Tidskriftsartikel (refereegranskat)abstract
- partially resistant cultivar. We conclud Cucurbit powdery mildew (CPM) is one of the most important plant protection problems in Swedish cucumber production. CPM fungi have developed resistance to the commonly used fungicide (Imazalil) rendering its current use less effective. We therefore screened a selection of alternative products, evaluating their ability to control CPM in seven small-scale, semi-commercial, greenhouse experiments. Products were screened for their ability to suppress CPM on a susceptible cultivar, in 2013. In 2015, the best treatments were tested in different combinations, in different intervals on a susceptible and a partially resistant cultivar. The treatment that gave the best CPM control was Sakalia in combination with wetting agent Yuccah, (based on Reynoutria sachaliensis and Yucca schidigera respectively) applied at 7-day intervals. This treatment was highly efficient on both cucumber cultivars. Sakalia mixed with Yuccah applied at 14-day intervals had an almost equally controlling effect on CPM. The microbial pesticides, Polyversum (Pythium oligandrum) and AQ10 (Ampelomyces quiscalis) and the fungicide Imazalil, provided no to poor control of CPM compared to control treatments. Hortistar (Silicon) partially reduced CPM infections and was more efficient on the e that Sakalia in combination with wetting agent Yuccah could efficiently control the disease even under the severe conditions caused by artificial inoculation. Further testing of this combination in commercial greenhouses will enable evaluation of the potential effects on yield and beneficial or pest insects. The knowledge gained from this study can be used to develop IPM tools for commercial production systems.
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| 44. |
- Saraiva, Marcia, et al.
(författare)
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Functional characterization of a tyrosinase gene from the oomycete Saprolegnia parasitica by RNAi silencing
- 2014
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Ingår i: Fungal Biology. - : Elsevier BV. - 1878-6146 .- 1878-6162. ; 118:7, s. 621-629
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Tidskriftsartikel (refereegranskat)abstract
- Here we describe the first application of transient gene silencing in Saprolegnia parasitica, a pathogenic oomycete that infects a wide range of fish, amphibians, and crustaceans. A gene encoding a putative tyrosinase from S. parasitica, SpTyr, was selected to investigate the suitability of RNA-interference (RNAi) to functionally characterize genes of this economically important pathogen. Tyrosinase is a mono-oxygenase enzyme that catalyses the O-hydroxylation of monophenols and subsequent oxidation of O-diphenols to quinines. These enzymes are widely distributed in nature, and are involved in the melanin biosynthesis. Gene silencing was obtained by delivering in vitro synthesized SpTyr dsRNA into protoplasts. Expression analysis, tyrosinase activity measurements, and melanin content analysis confirmed silencing in individual lines. Silencing of SpTyr resulted in a decrease of tyrosinase activity between 38 % and 60 %, dependent on the level of SpTyr-expression achieved. The SpTyr-silenced lines displayed less pigmentation in developing sporangia and occasionally an altered morphology. Moreover, developing sporangia from individual silenced lines possessed a less electron dense cell wall when compared to control lines, treated with GFP-dsRNA. In conclusion, the tyrosinase gene of S. parasitica is required for melanin formation and transient gene silencing can be used to functionally characterize gene S in S. parasitica.
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| 45. |
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| 46. |
- Stridh, L. J., et al.
(författare)
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Reduced efficacy of biocontrol agents and plant resistance inducers against potato early blight from greenhouse to field
- 2022
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Ingår i: Journal of Plant Diseases and Protection. - : Springer Science and Business Media LLC. - 1861-3829 .- 1861-3837. ; 129:4, s. 923-938
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Tidskriftsartikel (refereegranskat)abstract
- Early blight in potato, caused by Alternaria solani, is mainly controlled by frequent applications of synthetic fungicides. Reducing the use of synthetic fungicides in agriculture is desired to reach an overall sustainable development since the active components can be harmful for humans and for the ecosystem. In integrated pest management, IPM, the idea is to combine various measures, including optimized crop management, crop rotation, use of resistant cultivars, biological control agents (BCAs), plant resistance inducers, and fertilizers, to decrease the dependence on traditional chemical fungicides. In this paper, we present the results from greenhouse and field trials where we evaluated the effect of strategies aimed at reducing our reliance on synthetic fungicides including treatments with biological control agents (BCAs) (Pythium oligandrum, Polygandron®, and Bacillus subtilis, Serenade®) and plant resistance inducers (silicon products HortiStar® and Actisil®) for early blight in potato. The agents were applied separately or in combination with each other or with synthetic fungicides. In the greenhouse, trials application of these agents resulted in 50–95% reduction of infection by A. solani, but their combination did not generally improve the outcome. However, the effects were much smaller in the hand-sprayed field trials, 20–25% disease reduction and almost disappeared in full-scale field trials where application was done with tractor sprayers. In this article, we discuss possible reasons behind the drop in efficacy from greenhouse trials to full-size field evaluation.
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| 47. |
- Sundar, Jenifer Seematti, et al.
(författare)
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Pathogen-Mediated Stomatal Opening: A Previously Overlooked Pathogenicity Strategy in the Oomycete Pathogen Phytophthora infestans
- 2021
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Ingår i: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Phytophthora infestans, the most damaging oomycete pathogen of potato, is specialized to grow sporangiophore through opened stomata for secondary inoculum production. However, it is still unclear which metabolic pathways in potato are manipulated by P. infestans in the guard cell-pathogen interactions to open the stomata. Here microscopic observations and cell biology were used to investigate antagonistic interactions between guard cells and the oomycete pathogen. We observed that the antagonistic interactions started at the very beginning of infection. Stomatal movement is an important part of the immune response of potato to P. infestans infection and this occurs through guard cell death and stomatal closure. We observed that P. infestans appeared to manipulate metabolic processes in guard cells, such as triacylglycerol (TAG) breakdown, starch degradation, H2O2 scavenging, and NO catabolism, which are involved in stomatal movement, to evade these stomatal defense responses. The signal transduction pathway of P. infestans-induced stomatal opening likely starts from H2O2 and NO scavenging, along with TAG breakdown while the subsequent starch degradation reinforces the opening process by strengthening guard cell turgor and opening the stomata to their maximum aperture. These results suggest that stomata are a barrier stopping P. infestans from completing its life cycle, but this host defense system can be bypassed through the manipulation of diverse metabolic pathways that may be induced by P. infestans effector proteins.
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| 48. |
- Sundar, Jenifer Seematti, et al.
(författare)
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The hunt for sustainable biocontrol of oomycete plant pathogens, a case study of Phytophthora infestans
- 2021
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Ingår i: Fungal Biology Reviews. - : Elsevier BV. - 1749-4613 .- 1878-0253. ; 40, s. 53-69
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Forskningsöversikt (refereegranskat)abstract
- Late blight caused by the oomycete Phytophthora infestans is considered to be one of the most severe diseases of potato and tomato worldwide. Whilst current synthetic fungicides are efficient at controlling this disease, they are an environmental and economic burden. In line with EU directives to reduce the use of synthetic pesticides and increase the use of sustainable alternative disease control strategies that can form part of integrated pest management systems, practical biological control solutions are urgently needed. Despite the fact that there has been a large body of scientific research into microorganisms with potential for the biological control of late blight disease, relatively few commercial biocontrol agents, licensed to control late blight, exist. Furthermore, the practical uptake of those in Europe is lower than might be expected, suggesting that such solutions are not yet feasible, or effective. Here we review the scientific literature, focusing on the most recent developments in the hunt for efficient and sustainable biological control of late blight disease. We discuss the progress in our mechanistic understanding of mycoparasiteeprey interactions, in the context of late blight and the challenges and limitations to the use of such knowledge in practical disease control within a European context. (C) 2021 The Authors. Published by Elsevier Ltd on behalf of British Mycological Society.
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| 49. |
- Vetukuri, Ramesh R., et al.
(författare)
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Evidence for involvement of Dicer-like, Argonaute, and Histone Deacetylase proteins in gene silencing in Phytophthora infestans
- 2011
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Ingår i: Molecular plant pathology. - : Wiley. - 1464-6722 .- 1364-3703. ; 12:8, s. 772-785
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Tidskriftsartikel (refereegranskat)abstract
- Gene silencing may have a direct or indirect impact on many biological processes in eukaryotic cells, and is a useful tool for the determination of the roles of specific genes. In this article, we report silencing in Phytophthora infestans, an oomycete pathogen of potato and tomato. Gene silencing is known to occur in P. infestans, but its genetic basis has yet to be determined. Genes encoding the major components of the RNA interference (RNAi) pathway, Dicer-like (Pidcl1), Argonaute (Piago1-5) and RNA-directed RNA polymerase (Pirdr1), were identified in the P. infestans genome by comparative genomics, together with families of other genes potentially involved in gene silencing, such as histone deacetylases, histone methyltransferases, DEAD heli-cases, chromodomain proteins and a class 1 RNaseIII. Real-time reverse transcription-polymerase chain reaction demonstrated transcript accumulation for all candidate genes throughout the asexual lifecycle and plant infection, but at different levels of mRNA abundance. A functional assay was developed in which silencing of the sporulation-associated Picdc14 gene was released by the treatment of protoplasts with in vitro-synthesized double-stranded RNAs homologous to Pidcl1, Piago1/2 and histone deacetylase Pihda1. These results suggest that the components of gene silencing, namely Dicer-like, Argonaute and histone deacetylase, are functional in P. infestans. Our data demonstrate that this oomycete possesses canonical gene silencing pathways similar to those of other eukaryotes.
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