| 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. |
- 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 .- 1873-0272. ; 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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| 3. |
- 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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| 4. |
- 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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| 5. |
- 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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| 6. |
- 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
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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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| 7. |
- 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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| 8. |
- 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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| 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. |
- 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
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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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