| 1. |
- Armoniené, Rita, et al.
(author)
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Affordable Imaging Lab for Noninvasive Analysis of Biomass and Early Vigour in Cereal Crops
- 2018
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In: BioMed Research International. - : Hindawi Limited. - 2314-6133 .- 2314-6141.
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Journal article (peer-reviewed)abstract
- Plant phenotyping by imaging allows automated analysis of plants for various morphological and physiological traits. In this work, we developed a low-cost RGB imaging phenotyping lab (LCP lab) for low-throughput imaging and analysis using affordable imaging equipment and freely available software. LCP lab comprising RGB imaging and analysis pipeline is set up and demonstrated with early vigour analysis in wheat. Using this lab, a few hundred pots can be photographed in a day and the pots are tracked with QR codes. The software pipeline for both imaging and analysis is built from freely available software. The LCP lab was evaluated for early vigour analysis of five wheat cultivars. A high coefficient of determination (R-2 0.94) was obtained between the dry weight and the projected leaf area of 20-day-old wheat plants and R-2 of 0.9 for the relative growth rate between 10 and 20 days of plant growth. Detailed description for setting up such a lab is provided together with custom scripts built for imaging and analysis. The LCP lab is an affordable alternative for analysis of cereal crops when access to a high-throughput phenotyping facility is unavailable or when the experiments require growing plants in highly controlled climate chambers. The protocols described in this work are useful for building affordable imaging system for small-scale research projects and for education.
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| 2. |
- Edin, Eva, et al.
(author)
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Genetic diversity and occurrence of the F129L substitutions among isolates of Alternaria solani in south-eastern Sweden
- 2016
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In: Hereditas. - : Springer Science and Business Media LLC. - 0018-0661 .- 1601-5223. ; 153
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Journal article (peer-reviewed)abstract
- Background: Early blight, caused by the fungus Alternaria solani, occurs on potato mainly in the south-eastern part of Sweden, but also in other parts of the country. The aim of this study was to investigate the genetic diversity of A. solani populations from different potato growing regions in south-eastern Sweden using AFLP marker analysis. In addition, the cultured isolates were examined for substitutions in the gene encoding cytochrome b, associated with loss of sensitivity against QoI fungicides.Results: Nei's gene diversity index for the Swedish populations of A. solani revealed a gene diversity of up to 0.20. Also genetic differentiation was observed among populations of A. solani from different locations in south-eastern Sweden. The mitochondrial genotype of the isolates of A. solani was determined and both known genotypes, GI (genotype 1) and GII (genotype 2), were found among the isolates. The occurrence of the F129L substitution associated with a loss of sensitivity to strobilurins was confirmed among the GII isolates. In vitro conidial germination tests verified that isolates containing the F129L substitution had reduced sensitivity to azoxystrobin and, at a lower extent, to pyraclostrobin.Conclusions: Genetic diversity was relatively high among isolates of A. solani in south-eastern part of Sweden. F129L substitutions, leading to reduced sensitivity to strobilurins, have been established in field populations, which may have implications for the future efficacy of QoI fungicides.
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| 3. |
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| 4. |
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| 5. |
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| 6. |
- Gustavsson, Larisa, et al.
(author)
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Resistance to Neonectria ditissima in apple : insights from metabolomics and lipidomics analyses
- 2023
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In: Xxxi international horticultural congress (ihc2022). - : International Society for Horticultural Science. - 9789462613614 ; , s. 329-335, s. 329-336
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Conference paper (peer-reviewed)abstract
- European canker, caused by the necrotrophic fungus Neonectria ditissima, is the most serious disease in apple production in Sweden. The disease is favored by a relatively cool and rainy climate. The canker damages have a significant economic impact due to reduced bearing surface and increased orchard management costs. The possibilities for chemical and biological control are very limited. Therefore, directed breeding for new resistant cultivars is urgently needed. Knowledge of inheritance of canker resistance and understanding of molecular mechanisms involved in resistant and susceptible responses to fungal attacks would facilitate breeding. In this study, we evaluated the tempo-spatial differences in plant-pathogen interactions in a set of partially resistant and susceptible cultivars by conducting metabolomic and lipidomic analyses. The major trends in metabolomics and lipidomic profiles were common among cultivars, irrespective of the degree of susceptibility. Several metabolites and lipids varied with time point and cultivar under N. ditissima infection. Putative key metabolites such as suberic acid and jasmonic acid were upregulated in all cultivars upon infection. Additionally, several lipids exhibited changes 30 to 45 days post-inoculation. Thus, the approach used seems to have resulted in a rich data set to be further analyzed in light of ongoing QTL-mapping efforts.
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| 7. |
- Koc, Alexander, et al.
(author)
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Predicting yellow rust in wheat breeding trials by proximal phenotyping and machine learning
- 2022
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In: Plant Methods. - : Springer Science and Business Media LLC. - 1746-4811. ; 18
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Journal article (peer-reviewed)abstract
- Background High-throughput plant phenotyping (HTPP) methods have the potential to speed up the crop breeding process through the development of cost-effective, rapid and scalable phenotyping methods amenable to automation. Crop disease resistance breeding stands to benefit from successful implementation of HTPP methods, as bypassing the bottleneck posed by traditional visual phenotyping of disease, enables the screening of larger and more diverse populations for novel sources of resistance. The aim of this study was to use HTPP data obtained through proximal phenotyping to predict yellow rust scores in a large winter wheat field trial. Results The results show that 40-42 spectral vegetation indices (SVIs) derived from spectroradiometer data are sufficient to predict yellow rust scores using Random Forest (RF) modelling. The SVIs were selected through RF-based recursive feature elimination (RFE), and the predicted scores in the resulting models had a prediction accuracy of r(s) = 0.50-0.61 when measuring the correlation between predicted and observed scores. Some of the most important spectral features for prediction were the Plant Senescence Reflectance Index (PSRI), Photochemical Reflectance Index (PRI), Red-Green Pigment Index (RGI), and Greenness Index (GI). Conclusions The proposed HTPP method of combining SVI data from spectral sensors in RF models, has the potential to be deployed in wheat breeding trials to score yellow rust.
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| 8. |
- Kushwaha, Sandeep Kumar, et al.
(author)
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Differential Gene Expression Analysis of Wheat Breeding Lines Reveal Molecular Insights in Yellow Rust Resistance under Field Conditions
- 2020
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In: Agronomy. - : MDPI AG. - 2073-4395. ; 10
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Journal article (peer-reviewed)abstract
- The evolution of pathogens in the changing climate raises new challenges for wheat production. Yellow rust is one of the major wheat diseases worldwide, leading to an increased use of fungicides to prevent significant yield losses. The enhancement of the resistance potential of wheat cultivars is a necessary and environmentally friendly solution for sustainable wheat production. In this study, we aimed to identify the differentially expressed genes induced upon yellow rust infection in the field. Reference and de novo based transcriptome analysis was performed among the resistant and susceptible lines of a bi-parental population to study the global transcriptome changes in contrasting wheat genotypes. Based on the analysis, the de novo transcriptome analysis approach was found to be more supportive for field studies. Expression profiles, gene ontology, KEGG pathway analysis and enrichment studies indicated the relation between differentially expressed genes of wheat and yellow rust infection. The h0igh expression of genes related to non-race specific resistance along with pathogen-specific resistance might be a reason for the better resistance ability of a resistant wheat genotype in the field. The targeted metagenomic analysis of wheat samples revealed that Puccinia striiformis tritici was the most dominant pathogen along with other pathogens on the collected leaf material and validating the disease scoring carried out in the field and transcriptomics analyses.
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| 9. |
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| 10. |
- Odilbekov, Firuz, et al.
(author)
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GWAS-Assisted Genomic Prediction to Predict Resistance to Septoria Tritici Blotch in Nordic Winter Wheat at Seedling Stage
- 2019
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In: Frontiers in Genetics. - : Frontiers Media SA. - 1664-8021. ; 10
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Journal article (peer-reviewed)abstract
- Septoria tritici blotch (STB) disease caused by Zymoseptoria tritici is one of the most damaging diseases of wheat causing significant yield losses worldwide. Identification and employment of resistant germplasm is the most cost-effective method to control STB. In this study, we characterized seedling stage resistance to STB in 175 winter wheat landraces and old cultivars of Nordic origin. The study revealed significant (p < 0.05) phenotypic differences in STB severity in the germplasm. Genome-wide association analysis (GWAS) using five different algorithms identified ten significant markers on five chromosomes. Six markers were localized within a region of 2 cM that contained seven candidate genes on chromosome 1B. Genomic prediction (GP) analysis resulted in a model with an accuracy of 0.47. To further improve the prediction efficiency, significant markers identified by GWAS were included as fixed effects in the GP model. Depending on the number of fixed effect markers, the prediction accuracy improved from 0.47 (without fixed effects) to 0.62 (all non-redundant GWAS markers as fixed effects), respectively. The resistant genotypes and single-nucleotide polymorphism (SNP) markers identified in the present study will serve as a valuable resource for future breeding for STB resistance in wheat. The results also highlight the benefits of integrating GWAS with GP to further improve the accuracy of GP.
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| 11. |
- Odilbekov, Firuz, et al.
(author)
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Intact salicylic acid signalling is required for potato defence against the necrotrophic fungus Alternaria solani
- 2020
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In: Plant Molecular Biology. - : Springer Science and Business Media LLC. - 0167-4412 .- 1573-5028. ; 104, s. 1-19
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Journal article (peer-reviewed)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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| 12. |
- Odilbekov, Firuz, et al.
(author)
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Phenotyping early blight resistance in potato cultivars and breeding clones
- 2014
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In: Euphytica. - : Springer Science and Business Media LLC. - 0014-2336 .- 1573-5060. ; 197, s. 87-97
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Journal article (peer-reviewed)abstract
- Thirty-two potato cultivars/clones were evaluated for resistance to early blight using different methods. The evaluations were performed under field and greenhouse conditions. In the field experiments, plants were evaluated for disease symptoms, and the relative area under the disease progress curve and percent defoliation were determined. In the greenhouse experiments, leaf lesion sizes were determined on either intact plants or detached leaves after drop inoculation with Alternaria solani. The effect of leaf position (lower, middle or upper part of the plant) on lesion size was investigated. There was no correlation between lesion sizes on lower leaves and upper leaves after inoculation. However, significant correlations between lesion sizes on lower and middle leaves and also between middle and upper leaves were found. Furthermore, we found significant correlation between the results of resistance studies in the field and in intact plant inoculation experiments in the greenhouse. In contrast, results from the detached-leaf experiment were not correlated with either greenhouse intact plant tests or field results. The results indicate that using detached-leaf assays for screening potato for early blight resistance is not accurate. We found significant differences in resistance to A. solani among cultivars/clones in both the field and in greenhouse experiments.
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| 13. |
- Odilbekov, Firuz, et al.
(author)
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Proximal Phenotyping and Machine Learning Methods to Identify Septoria Tritici Blotch Disease Symptoms in Wheat
- 2018
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In: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 9
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Journal article (peer-reviewed)abstract
- Phenotyping with proximal sensors allow high-precision measurements of plant traits both in the controlled conditions and in the field. In this work, using machine learning, an integrated analysis was done from the data obtained from spectroradiometer, infrared thermometer, and chlorophyll fluorescence measurements to identify most predictive proxy measurements for studying Septoria tritici blotch (STB) disease of wheat. The random forest (RF) models for chlorosis and necrosis identified photosystem II quantum yield (QY) and vegetative indices (Ms) associated with the biochemical composition of leaves as the top predictive variables for identifying disease symptoms. The RF model for chlorosis was validated with a validation set (R-2: 0.80) and in an independent test set (R-2: 0.55). Based on the results, it can be concluded that the proxy measurements for photosystem II, chlorophyll content, carotenoid, and anthocyanin levels and leaf surface temperature can be successfully used to detect STB. Further validation of these results in the field will enable application of these predictive variables for detection of STB in the field.
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| 14. |
- Odilbekov, Firuz, et al.
(author)
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QTL Mapping and Transcriptome Analysis to Identify Differentially Expressed Genes Induced by Septoria Tritici Blotch Disease of Wheat
- 2019
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In: Agronomy. - : MDPI AG. - 2073-4395. ; 9
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Journal article (peer-reviewed)abstract
- Resistance to Septoria tritici blotch (STB) is an economically important trait in many wheat-breeding programs across the world. Several quantitative trait loci (QTL) for STB resistance were identified in wheat but due to the dynamic pathogen population it is necessary to continuously identify new resistance genes/QTL and determine the underlying resistance mechanism. In this work, we integrated QTL mapping and transcriptome profiling to identify candidate genes underlying QTL associated with STB resistance in bread wheat at the seedling stage. The results revealed four QTL on chromosomes 1BS, 1BL, 3AS and 3DL for STB resistance. Among these, two QTL on 2BL and 3DL were mapped for chlorosis, necrosis and pycnidia while the other two on 1BS and 3AS were associated with necrosis and pycnidia. Among the four identified QTL, genes were identified in three QTL (1BS, 2BL and 3DL). In total, 238 differentially expressed genes (DEGs) were localized in 1BS, 16 DEGs in 2BL and 80 DEGs in 3DL QTL region respectively. F-box protein, NBS-LRR disease resistance genes and receptor-like protein kinase were the most over-represented. The results emphasize the importance of integrating QTL and transcriptome analysis to accelerate the identification of key genes underlying the traits of interest.
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| 15. |
- Odilbekov, Firuz, et al.
(author)
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QTL mapping for field resistance to wheat blast in the Caninde#1/Alondra population
- 2020
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In: TAG Theoretical and Applied Genetics. - : Springer Science and Business Media LLC. - 0040-5752 .- 1432-2242. ; 133, s. 2673-2683
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Journal article (peer-reviewed)abstract
- Key message Wheat blast resistance in Caninde#1 is controlled by a major QTL on 2NS/2AS translocation and multiple minor QTL in an additive mode. Wheat blast (WB) is a devastating disease in South America, and it recently also emerged in Bangladesh. Host resistance to WB has relied heavily on the 2NS/2AS translocation, but the responsible QTL has not been mapped and its phenotypic effects in different environments have not been reported. In the current study, a recombinant inbred line population with 298 progenies was generated, with the female and male parents being Caninde#1 (with 2NS) and Alondra (without 2NS), respectively. Phenotyping was carried out in two locations in Bolivia, namely Quirusillas and Okinawa, and one location in Bangladesh, Jashore, with two sowing dates in each of the two cropping seasons in each location, during the years 2017-2019. Genotyping was performed with the DArTseq (R) technology along with five previously reported STS markers in the 2NS region. QTL mapping identified a major and consistent QTL on 2NS/2AS region, explaining between 22.4 and 50.1% of the phenotypic variation in different environments. Additional QTL were detected on chromosomes 1AS, 2BL, 3AL, 4BS, 4DL and 7BS, all additive to the 2NS QTL and showing phenotypic effects less than 10%. Two codominant STS markers,WGGB156andWGGB159, were linked proximally to the 2NS/2AS QTL with a genetic distance of 0.9 cM, being potentially useful in marker-assisted selection.
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| 16. |
- Odilbekov, Firuz, et al.
(author)
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QTL Mapping for resistance to early blight in a tetraploid potato population
- 2020
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In: Agronomy. - : MDPI AG. - 2073-4395. ; 10
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Journal article (peer-reviewed)abstract
- Early blight of potato, caused by Alternaria solani, is an economically important foliar disease in most potato-growing regions. Growing cultivars with higher levels of resistance to early blight can reduce tuber yield losses and the need for fungicide applications. In this research, a bi-parental tetraploid potato population, segregating for resistance to early blight in leaves and tubers, was characterized to identify novel quantitative trait loci (QTL) associated with foliar and tuber early blight resistance. Assessment of the disease resistance in the foliage was performed by field evaluation and in tuber under controlled conditions. Results from this study revealed significant differences (P < 0.001) in resistance to A. solani among potato clones both in the leaves and in tubers. There was no statistically significant correlation (r = 0.06, P = 0.35) between the resistance scores from leaves and tubers. Several clones exhibited; however, high levels of resistance both in leaves and tubers and are; thus, promising candidates for breeding for early blight resistance. Linkage mapping revealed several QTL for early blight affecting both foliage and tubers. QTL associated with disease resistance in the tuber were found on chromosomes 1, 2, 3, 4, 8, 11 and 12. QTL associated with disease resistance in foliage were also examined for independence from defoliation, and independent QTL were; thus, found on chromosomes 5 and 11.
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| 17. |
- Odilbekov, Firuz
(author)
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Resistance to early blight in potato and genetic structure of the pathogen population in Southeast Sweden
- 2015
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Doctoral thesis (other academic/artistic)abstract
- Potato early blight caused by the necrotrophic fungus Alternaria solani is a common foliar disease in many potato-growing regions. Application of fungicides is commonly used to effectively control the disease, although they are undesirable due to environmental consequences. Use of resistant cultivars would be the most optimal solution, but there are no cultivars with high level of resistance available on the market. In the present thesis, assessments of early blight resistance both in leaves and tubers of potato cultivars/clones were performed by applying different screening methods (field and greenhouse). Plant defence signalling in response to A. solani infection with main emphasis on salicylic (SA) and jasmonic acid (JA) hormones, was also studied. Furthermore, the genetic variability in A. solani populations from different potato growing regions of southeast Sweden was investigated. The fungal isolates were analysed for the F129L substitutions, which are associated with loss of sensitivity to QoI fungicides. In addition, field experiments were conducted to determine the occurrence of the F129L substitution and genetic shifts in the population during one growing season in response to two different fungicide strategies. Cultivars/clones revealed significant differences in resistance to A. solani both in leaves and tubers irrespective of screening method. Results from field and intact plant inoculation experiments were significantly correlated but there were no correlations observed between these two methods and detached leaf assays. Some cultivars/clones showed relatively higher level of resistance to the pathogen. Results from the data suggested that SA appears to be responsible for regulating symptom development while JA dependent COI1 defense signaling is important to inhibit fungal growth during early stages of infection. Microarray analysis showed rapid defense responses to A. solani infection mediated by partially overlapping SA and COI1 dependent jasmonic acid (JA) signaling. It was also observed that JA/ethylene signaling responses dominate at later time points. The genetic variability was relatively high among isolates of A. solani and significant genetic differentiation was found among populations from different locations in southeast Sweden. Two mitochondrial genotypes (GI and GII) were found among the isolates but the F129L substitution was only detected in GII isolates. Results from the field experiment showed that application of azoxystrobin (QoI fungicide) alone did not control the disease; better disease control was achieved with boscalid combined with pyraclostrobin. Similar results were obtained for yield. Moreover, results of sensitivity tests showed that isolates with the F129L substitution were less sensitive to azoxystrobin. AFLP analysis indicated within season changes in the A.solani population, especially at the end of the season.
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| 18. |
- Odilbekov, Firuz, et al.
(author)
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Within-season changes in Alternaria solani populations in potato in response to fungicide application strategies
- 2019
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In: European Journal of Plant Pathology. - : Springer Science and Business Media LLC. - 0929-1873 .- 1573-8469. ; 155, s. 953-965
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Journal article (peer-reviewed)abstract
- Early blight, caused by the fungus Alternaria solani, is a common foliar disease in potato. Quinone outside inhibitor (QoIs) fungicides have commonly been used against A. solani. To avoid or delay development of fungicide resistance it is recommended to alternate or combine fungicides with different modes of action. Therefore, we compared two different fungicide programs against early blight in field trials and studied within season changes in the pathogen population. An untreated control was compared with treatments using azoxystrobin alone and with a program involving difenoconazole followed by boscalid and pyraclostrobin combined. Isolates of A. solani were collected during the growing season and changes in the population structure was investigated. We also screened for the amino acid substitution in the cytochrome b gene and investigated changes in sensitivity to azoxystrobin. Treatment with azoxystrobin alone did not improve disease control in 2014 when the disease pressure was high. However, lower severity of the disease was observed after combined use of difenoconazole, boscalid and pyraclostrobin. The efficacy of both fungicide treatments were similar during the field trial in 2017. Two mitochondrial genotypes (GI and GII) were found among isolates, where all isolates, except two, were GII. All GII isolates had the F129 L substitution while the two GI isolates were wild type. Population structure analysis and principal component analysis (PCA) of amplified fragment length polymorphisms (AFLP) data revealed within season changes in the A. solani populations in response to fungicide application. Isolates with the F129 L substitution had reduced sensitivity to azoxystrobin in vitro and their sensitivity tended to decrease with time.
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| 19. |
- Skytte Af Sätra, Jonas, et al.
(author)
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Genetic Status of the Swedish Central collection of heirloom apple cultivars
- 2020
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In: Scientia Horticulturae. - : Elsevier BV. - 0304-4238 .- 1879-1018. ; 272
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Journal article (peer-reviewed)abstract
- Cultivated apple is one of the most widely grown fruit crops worldwide. With the introduction of modern apple cultivars, from foreign and national breeding programs, the use of local cultivars decreased during the 20th century. In order to minimize genetic erosion and avoid loss of special genotypes, a number of local clonal archives were established across Sweden, with the goal of retaining old and local cultivars. About 220 apple cultivars, appointed for preservation, obtained the status of mandate cultivars. Initially, they were identified based on pomological traits, but prior to the establishment of the Swedish Central Collection they were genotyped with simple sequence repeat (SSR) markers. SSR markers helped to evaluate the status of the preserved material, as well as to find the best possible true-to-type source for propagation, thus guiding the establishment of the Central Collection. Recently, 215 accessions from this collection were genotyped using the 20 K apple Infinium (R) single nucleotide polymorphism (SNP) array, in order to gain insight into its genetic structure. The initial SSR analysis confirmed the identity of multiple samples with the same cultivar name grown in different locations and identified several mislabeled samples. In the subsequent SNP analysis we identified 30 clonal relationships and a number of parent-offspring relationships, including 18 trios. We also identified five cultivar samples with inconsistent ploidy levels between the SNP and SSR data, in some cases indicating problematic samples preserved in either the Central Collection or some of the local clonal archives. These cultivars need further investigation to ensure their true-to-typeness. Furthermore, the Swedish Central Collection has continued to grow since the onset of this work and now contains additional cultivars, which should be included in future studies. The results indicate that a number of the preserved mandate cultivars holds high potential value for modern breeding programs.
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| 20. |
- Skytte Af Sätra, Jonas, et al.
(author)
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Parametric mapping of QTL for resistance to European canker in apple in 'Aroma' x 'Discovery'
- 2023
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In: Tree Genetics and Genomes. - : Springer Science and Business Media LLC. - 1614-2942 .- 1614-2950. ; 19
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Journal article (peer-reviewed)abstract
- Resistance to European canker (Neonectria ditissima) in apple is currently one of the most important breeding targets for commercial production in Sweden. Previous research has identified significant genetic variation in susceptibility to the disease, with the local Swedish cultivar 'Aroma' considered as one of the most resistant cultivars. Identification of genetic regions underlying the resistance of this cultivar would be a valuable tool for future breeding. Thus, we performed Bayesian quantitative trait loci (QTL) mapping for resistance to European canker in a full-sib family of 'Aroma' x 'Discovery'. Mapping was performed with the area under the disease progression curves (AUDPCs) from all seven (AUDPC_All7) and the first four assessments (AUDPC_First4), and three parameters of a sigmoid growth model for lesion length. As a scale for the effect of the different parameters, historic phenotypic data from screenings of a genetically diverse germplasm was compiled and re-analyzed. The parametrization of the data on lesion growth increased the number of QTL that could be identified with high statistical power, and provided some insight into their roles during different stages of disease development in the current experimental setup. Five QTL regions with strong or decisive evidence were identified on linkage groups 1, 8, 15, and 16. The QTL regions could be assigned to either of the parameters lesion length at the first assessment ('LL_A1'), the maximal lesion growth rate (lesion length doubling time, 't_gen'), and the lesion length at girdling ('LL_G'). Three of these QTL were traced along the pedigrees of some known relatives of the FS family, and discussed in relation to future crosses for breeding and genetic research.
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| 21. |
- Stridh, L. J., et al.
(author)
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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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In: 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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Journal article (peer-reviewed)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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| 22. |
- Vélëz, Heriberto, et al.
(author)
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Transformation and gene-disruption in the apple-pathogen, Neonectria ditissima
- 2022
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In: HEREDITAS. - : Springer Science and Business Media LLC. - 1601-5223. ; 159
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Journal article (peer-reviewed)abstract
- Background Apple production in Sweden and elsewhere is being threatened by the fungus, Neonectria ditissima, which causes a disease known as European canker. The disease can cause extensive damage and the removal of diseased wood and heavily infected trees can be laborious and expensive. Currently, there is no way to eradicate the fungus from infected trees and our knowledge of the infection process is limited. Thus, to target and modify genes efficiently, the genetic transformation technique developed for N. ditissima back in 2003 was modified. Results The original protocol from 2003 was upgraded to use enzymes currently available in the market for making protoplasts. The protoplasts were viable, able to uptake foreign DNA, and able to regenerate back into a mycelial colony, either as targeted gene-disruption mutants or as ectopic mutants expressing the green fluorescent protein (GFP). Conclusions A new genetic transformation protocol has been established and the inclusion of hydroxyurea in the buffer during the protoplast-generation step greatly increased the creation of knockout mutants via homologous recombination. Pathogenicity assays using the GFP-mutants showed that the mutants were able to infect the host and cause disease.
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| 23. |
- Zakieh, Mustafa, et al.
(author)
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Characterizing Winter Wheat Germplasm for Fusarium Head Blight Resistance Under Accelerated Growth Conditions
- 2021
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In: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 12
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Journal article (peer-reviewed)abstract
- Fusarium head blight (FHB) is one of the economically important diseases of wheat as it causes severe yield loss and reduces grain quality. In winter wheat, due to its vernalization requirement, it takes an exceptionally long time for plants to reach the heading stage, thereby prolonging the time it takes for characterizing germplasm for FHB resistance. Therefore, in this work, we developed a protocol to evaluate winter wheat germplasm for FHB resistance under accelerated growth conditions. The protocol reduces the time required for plants to begin heading while avoiding any visible symptoms of stress on plants. The protocol was tested on 432 genotypes obtained from a breeding program and a genebank. The mean area under disease progress curve for FHB was 225.13 in the breeding set and 195.53 in the genebank set, indicating that the germplasm from the genebank set had higher resistance to FHB. In total, 10 quantitative trait loci (QTL) for FHB severity were identified by association mapping. Of these, nine QTL were identified in the combined set comprising both genebank and breeding sets, while two QTL each were identified in the breeding set and genebank set, respectively, when analyzed separately. Some QTLs overlapped between the three datasets. The results reveal that the protocol for FHB evaluation integrating accelerated growth conditions is an efficient approach for FHB resistance breeding in winter wheat and can be even applied to spring wheat after minor modifications.
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