| 1. |
- Ahmadi Afzadi, Masoud, et al.
(författare)
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Biochemical contents of apple peel and flesh affect level of partial resistance to blue mold
- 2015
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Ingår i: Postharvest Biology and Technology. - : Elsevier BV. - 0925-5214. ; 110, s. 173-182
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Tidskriftsartikel (refereegranskat)abstract
- Apple fruit contains a wide range of chemical compounds that may contribute to resistance against blue mold caused by Penicillium expansum. In the present study, contents of total titratable acidity, malic acid, total phenols and 10 individual phenolic compounds were quantified in peel and flesh fractions of both control and blue mold-inoculated fruits of 24 apple cultivars. In addition to the significant variation among cultivars in terms of all quantified compounds, correlation analysis revealed a significant impact of total phenols and individual phenols like flavonols and procyanidins B2 in the peel fraction, on blue mold resistance in the inoculated fruits. Multivariate analyses on data for chemical compounds in peel tissue of inoculated fruits, could also separate resistant and susceptible cultivars. These findings can be useful in breeding programs since higher levels of phenolic compounds may indicate better resistance in apple cultivars. (C) 2015 Elsevier B.V. All rights reserved.
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| 2. |
- Ahmadi Afzadi, Masoud, et al.
(författare)
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Genetics of resistance to blue mould in apple: inoculation-based screening, transcriptomics and biochemistry
- 2016
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Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 1127, s. 55-60
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Konferensbidrag (refereegranskat)abstract
- Blue mould caused by Penicillium expansum is a major contributor to loss of marketable fruit during storage. Damage is also aggravated by the prohibition of postharvest fungicides in many countries, and in organic production everywhere. Robust data on levels of resistance to this disease are crucial for further research and for breeding of improved cultivars. Inoculation of fruit with fungal spores and estimation of the diameter of resulting lesions after cold storage demonstrated significant variation among cultivars. In addition, cultivars with high firmness at harvest and little softening, i.e., loss of firmness during storage, had less susceptibility, as also did late-ripening cultivars. In another part of the study, a possible association between lesion diameter and chemical contents in fruit flesh and fruit peel of 23 cultivars was investigated. Content of different quercetins and procyanidin B2 was positively associated with the level of tolerance. Samples taken after inoculation showed stronger association with the chemical contents than did samples of control fruit, suggesting that disease development had triggered a defence reaction. In a third part of the study, gene regulation in apple fruit after inoculation was evaluated in two relatively resistant and two relatively susceptible cultivars using an AryANE chip covering 60K apple transcripts. Validation of the most highly up-and down-regulated genes was undertaken using qPCR. Some genes related to disease resistance, biosynthesis of flavonoids and to cell-wall structure were identified as most likely to be responsible for differences in susceptibility to blue mould. These results will be used to search for candidate genes that can be used in marker-assisted selection in apple breeding.
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| 3. |
- Ahmadi Afzadi, Masoud, et al.
(författare)
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Genome-wide expression analysis suggests a role for jasmonates in the resistance to blue mold in apple
- 2018
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Ingår i: Plant growth regulation (Print). - : Springer Science and Business Media LLC. - 0167-6903 .- 1573-5087. ; 85:3, s. 375-387
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Tidskriftsartikel (refereegranskat)abstract
- Blue mold, caused by the necrotrophic fungal pathogen Penicillium expansum, causes serious postharvest losses in apple, and threatens human health through production of the potent mycotoxin patulin. Recent studies indicate a quantitative control of resistance against this disease in apple cultivars. A whole genome apple microarray covering 60k transcripts was used to identify gene(s) that appear to be differentially regulated between resistant and susceptible cultivars in P. expansum-infected fruits. A number of potential candidates was encountered among defense- and oxidative stress-related genes, cell wall modification and lignification genes, and genes related to localization and transport. Induction of one cell wall-related gene and three genes involved in the 'down-stream' flavonoid biosynthesis pathway, demonstrates the fundamental role of the cell wall as an important barrier, and suggests that fruit flavonoids are involved in the resistance to blue mold. Moreover, exogenous application of the plant hormone methyl jasmonate (MeJA) reduced the symptoms resulting from inoculating apples with P. expansum. This is the first report linking MeJA and activation of cell wall and flavonoid pathway genes to resistance against blue mold in a study comparing different cultivars of domesticated apple. Our results provide an initial categorization of genes that are potentially involved in the resistance mechanism, and should be useful for developing tools for gene marker-assisted breeding of apple cultivars with an improved resistance to blue mold.
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| 4. |
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| 5. |
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| 6. |
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| 7. |
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| 8. |
- Dey, Estera, et al.
(författare)
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Alkylresorcinols isolated from rye bran by supercritical fluid of carbon dioxide and suspended in a food-grade emulsion show activity against Penicillium expansum on apples
- 2013
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Ingår i: Archives of Phytopathology and Plant Protection. - : Informa UK Limited. - 1477-2906 .- 0323-5408. ; 46:1, s. 105-119
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Tidskriftsartikel (refereegranskat)abstract
- Apple cultivars are attacked by many fungal diseases, both on the tree and during storage. One of the most serious is blue mould, caused by Penicillium expansum. In this study, 5-(n)-alkylresorcinols (AR) were isolated from rye bran by the supercritical fluid of carbon dioxide and were used for the preparation of bioactive emulsions. These emulsions were applied to harvested fruit of five apple varieties to determine the levels of antifungal activity. A significant inhibition of disease symptoms was obtained after spraying some of the prepared AR emulsions on fruits that had been experimentally infected with Penicillium expansum. The most effective emulsions consisted of 0.025% (m/v) ARs, 0.1% (m/v) xanthan gum, 0.5% (m/v) Synperonic 91/6 or PDMs-copolymer, 0.2% (m/v) Tween 20, 1% (m/v) Trioleate, 2% (m/v) oleylalcohol, 2% (m/v) PEG 400, 5% (m/v) CaCl2 or NaCl suspended in water.
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| 9. |
- Ghasemkhani, Marjan, et al.
(författare)
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Assessment of diversity and genetic relationships of Neonectria ditissima: the causal agent of fruit tree canker
- 2016
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Ingår i: Hereditas. - : Springer Science and Business Media LLC. - 0018-0661 .- 1601-5223. ; 153, s. 11-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Neonectria ditissima is one of the most important fungal pathogens of apple trees, where it causes fruit tree canker. Information about the amount and partitioning of genetic variation of this fungus could be helpful for improving orchard management strategies and for breeding apple cultivars with high levels of genetically determined resistance. In this study single-spore Neonectria isolates originating from both the same and from different perithecia, apple cultivars and apple orchards in Sweden and Belgium, were evaluated for AFLP- and SSR-based genetic similarity and for mating system.Results: Seven SSR loci produced a total of 31 alleles with an average of 4 alleles per locus, while 11 AFLP primer combinations produced an average of 35 fragments per primer combination and 71 % polymorphic fragments. An AFLP-based analysis of molecular variance (AMOVA) revealed that 89 % of the variation was found within orchards and 11 % between orchards. Genetic similarity among the studied isolates was illustrated with a principal coordinate analyseis (PCoA) and a dendrogram. AFLP-based Jaccard's similarity coefficients were the highest when single-ascospore isolates obtained from the same perithecium were compared, medium-high for isolates from different perithecia on the same tree, and lowest when isolates from different trees were compared.Conclusions: Based on the results of PCoA and AMOVA analysis, isolates from the same or geographically close orchards did not group together. Since AFLP profiles differed also when single-ascospore isolates from the same perithecium were compared, the mating system of N. ditissima is most likely heterothallic.
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| 10. |
- Ghasemkhani, Marjan, et al.
(författare)
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Cut-off shoots method for estimation of partial resistance in apple cultivars to fruit tree canker caused by Neonectria ditissima
- 2015
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Ingår i: Acta Agriculturae Scandinavica, Section B - Soil and Plant Science. - : Informa UK Limited. - 0906-4710 .- 1651-1913. ; 65, s. 412-421
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Tidskriftsartikel (refereegranskat)abstract
- Fruit tree canker, caused by the fungus Neonectria ditissima, is an economically devastating disease in apple orchards, especially in north-western Europe. Complete resistance has not yet been reported in apple, but variation in levels of partial resistance has been described and could be valuable in plant breeding programmes. A screening method based on spore inoculation of manually inflicted leaf scars on cut shoots was evaluated for reliability and repeatability in discrimination of 11 apple cultivars during two years - 2012 and 2013 - in two different facilities - biotron and standard greenhouse - and different time periods (February-May). The resulting cankers were counted (infection percentage), first appearance noted (incubation period) and lesion size measured at regular intervals during a period of 25-29 days for comparison of resistance levels. Results of two-way analysis of variance and correlation analyses showed that the area under the disease progress curve yielded the most robust data. This parameter was then applied for screening 30 apple cultivars using the same cut-shoot method. 'Elise' showed very high susceptibility, while the ornamental 'Prairifire' showed the highest level of partial resistance. Results suggested that cut shoots can be used to assess levels of resistance among cultivars, but great care must be taken to provide stable experimental conditions.
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| 11. |
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| 12. |
- Ghasemkhani, Marjan, et al.
(författare)
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Real-time PCR for detection and quantification, and histological characterization of Neonectria ditissima in apple trees
- 2016
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Ingår i: Trees - Structure and Function. - : Springer Science and Business Media LLC. - 0931-1890 .- 1432-2285. ; 30, s. 1111-1125
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Tidskriftsartikel (refereegranskat)abstract
- Neonectria ditissima, the causal pathogen of fruit tree canker, is a sordariomycete fungus that affects apple orchards, especially in north-western Europe. To prevent serious disease epidemics, an accurate, rapid, and sensitive method for detection of N. ditissima is needed for pathogen identification. A quantitative real-time PCR (qPCR) assay was developed for both detection and quantification of this pathogen in infected apple cultivars. Several primer sets were designed from regions of the β-tubulin gene. One primer set passed several validation tests, and the melting curve confirmed species-specific amplification of the correct product. In addition, the N. ditissima biomass could be detected at variable amounts in samples from the infection sites of six different cultivars, with ‘Aroma' having the lowest amount of N. ditissima biomass and ‘Elise' the highest. To complement the qPCR results, tissue from detached shoots and 1-year-old trees of ‘Cox's Orange Pippin' (susceptible) and ‘Santana' (partially resistant) was used in a histopathology study. In both detached shoots and trees, fungal hyphae were found in cells of all tissues. No qualitative differences in the anatomy of the infected samples were observed between the cultivars. In the detached shoot experiment, both cultivars were affected but differences in the rate of disease progression suggest that the partially resistant cultivar could resist the fungus longer. The qPCR assay developed in our study produced reproducible results and can be used for detection of N. ditissima in infected trees.
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| 13. |
- Ghasemkhani, Marjan, et al.
(författare)
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Screening for Partial Resistance to Fruit Tree Canker in Apple Cultivars
- 2015
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Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 1099, s. 687-690
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Konferensbidrag (refereegranskat)abstract
- Fruit tree canker in apple, caused by the fungus Neonectria ditissima, is considered as a serious economic problem in apple orchards, especially in northwestern Europe. This fungus produces cankers on the wood of branches and trunks, and severe attacks can result in the loss of limbs or whole trees. The fungus produces conidia and ascospores, both of which are dispersed and cause infection during prolonged periods of rainy weather. Apple cultivars show variable levels of partial resistance to the fungus, whereas complete resistance has not yet been reported. Therefore, apple genotypes with high levels of genetically determined resistance should be identified for use in apple breeding. In this study, ten apple cultivars were screened for resistance to N. ditissima. For each cultivar, both potted trees and cut-off shoots in glass bottles were inoculated in a greenhouse. The resulting lesions were measured and disease progression curves were calculated; AUC (area under curve) was used for comparisons of infection severity. Significant differences between cultivars were observed in both experiments. The cultivar 'Rodluvan' showed the highest degree of resistance in both experiments, while the most susceptible were 'Jonathan'(cut shoots) and 'Akero' (potted trees).
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| 14. |
- Gustavsson, Larisa, et al.
(författare)
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Do we preserve unique apple germplasm?
- 2011
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Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 918, s. 661-666
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Konferensbidrag (refereegranskat)
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| 15. |
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| 16. |
- Gustavsson, Larisa, et al.
(författare)
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Screening of Apple Cultivars for Resistance to European Canker, Neonectria ditissima
- 2013
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Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 976, s. 529-536
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Konferensbidrag (refereegranskat)abstract
- European canker, caused by the fungus Neonectria ditissima, is a severe problem in apple production both in Sweden and in many other northern European countries. Even when applying fungicides and good horticultural practices, canker damage occurs almost yearly in nurseries and orchards. Some years, devastating outbreaks destroy numerous trees. To date, complete resistance to N. ditissima is not known in apple. For further research and plant breeding, heritable variation in quantitative resistance should be investigated by phenotyping large sets of cultivars. In the present project, 55 apple cultivars were screened for resistance to N. ditissima. One-year-old shoots from mature trees were inoculated in the greenhouse with a standardized volume and concentration of conidia suspension using different inoculation methods. Two-year-old trees of five cultivars were inoculated in the field. Length of the occurring cankers was measured at regular intervals throughout a period of up to three months. The investigated cultivars showed considerable differences in colonization rate. In cultivars known to be highly resistant, i.e., 'Santana', lesions progressed much slower compared to susceptible cultivars like 'Cox's Orange Pippin' and 'James Grieve'. Since the inoculation-based phenotyping is demanding in labour and time (duration), especially when the test is performed on grafted trees, qPCR-based assessment of fungal biomass at early stages of infection was explored as an alternative or complementary approach for phenotyping.
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| 17. |
- Gustavsson, Larisa, et al.
(författare)
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Varför äpplen på banken?
- 2011
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Ingår i: Pomologen. - 1650-9455. ; 11, s. 10-15
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 18. |
- Loots, Sonja, et al.
(författare)
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Distribution, habitat profile and genetic variability of Namibian succulent Lithops ruschiorum
- 2019
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Ingår i: Bothalia - African Biodiversity and Conservation. - : South African National Biodiversity Institute. - 0006-8241 .- 2311-9284. ; 49
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Tidskriftsartikel (refereegranskat)abstract
- Background: The species-rich flora of southern Africa comprises a high number of endemics, including succulents such as the flowering stones in the genus Lithops, but conservation status for these species is not well underpinned because detailed field data and assessments of genetic diversity are lacking.Objectives: We wanted to assess plant abundance and identify factors that may affect survival in Lithops ruschiorum through carefully conducted field surveys, and to determine amount and partitioning of genetic variation by amplified fragment length polymorphism (AFLP) analysis.Method: Field surveys were carried out in nine populations in Namibia. The most meticulously studied population was divided into 51 sites, while another 43 sites were recognised in the remaining eight populations. At each site, occupied area and number of plants were recorded as well as altitude, aspect, slope, soil texture and substrate. Amplified fragment length polymorphism markers were employed to study 52 individuals from seven populations. Results: In total, 8465 individuals were recorded. Plant density and/or plant number was associated with aspect, slope, soil texture, substrate and geographic distance from the coast. Analysis of molecular variation showed that 95% of the variability occurs within populations. Genetic and geographic distances among populations were correlated suggesting an isolation-by-distance pattern.Conclusion: Results are concordant with a strong impact of fog-based precipitation on plant density in the coastal populations, whereas rain probably is more important at one population which is situated further inland. Within-population genetic variation was medium high as usually reported for perennial, outcrossing species, but the low population differentiation implies considerable gene flow and/or population fragmentation.
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| 19. |
- Loots, Sonja, et al.
(författare)
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Genetic variation among and within Lithops species in Namibia
- 2019
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Ingår i: Plant Systematics and Evolution. - : Springer Science and Business Media LLC. - 0378-2697 .- 1615-6110 .- 2199-6881.
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Tidskriftsartikel (refereegranskat)abstract
- The dwarf succulent genus Lithops is endemic to Southern Africa and of considerable conservation concern. Species delimitation is often problematic and based mainly on leaf morphology, which is strongly associated with habitat. Relationships between taxa and populations in Namibia were studied with amplified fragment length polymorphisms using 44 wild Lithops populations representing 15 species and 23 taxa. Four primer pairs produced 92 polymorphic bands in the 223 samples. Expected heterozygosity (H-e) within taxa ranged from 0.086 to 0.450. Genetic and geographic distances were correlated according to a Mantel test. Analysis of molecular variance showed only 23% variation among the 15 investigated species. Genetic differentiation and structuring were investigated with a principal coordinate analysis, a neighbour-joining and a Bayesian phylogeny, a Bayesian clustering analysis and a discriminant analysis of principal components. In all five analyses, L. optica and L. herrei, which differ only in flower colour, clustered closely together and are here combined under L. optica. The morphologically similar species L. amicorum and L. karasmontana clustered together. Lithops amicorum is therefore reduced to subspecific level: L. karasmontana subsp. amicorum, comb. nov. Subspecific taxa overlapped to a large extent except in L. karasmontana where 13% of the variability resided among subspecies, whereas the nominal subspecies differed from subsp. bella and subsp. eberlanzii; the latter two could not be separated and are here combined under L. karasmontana subsp. bella.
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| 20. |
- Loots, Sonja, et al.
(författare)
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Towards better risk assessment for conservation of flowering stones: plant density, spatial pattern and habitat preference of Lithops pseudotruncatella in Namibia
- 2017
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Ingår i: South African Journal of Botany. - : Elsevier BV. - 0254-6299 .- 1727-9321. ; 109, s. 112-115
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Tidskriftsartikel (refereegranskat)abstract
- To provide a better understanding of spatial pattern and habitat preferences for a cryptic xerophyte, a number of variables were investigated in a 10,000 m(2) (1 ha) study area in a population of L. pseudotruncatella; plant density, spatial arrangement of plants, and habitat specificity. Two censuses, carried out in dry season and in rainy season, revealed a total of 448 and 860 plants, respectively, with a severely clumped distribution. Five out of seven plant density estimation methods, applied in dry season, produced data that vastly over-or under-estimated plant number while Adaptive Cluster Sampling and the Belt Transect method were more accurate, with 557 and 540 plants, respectively. Plant number in 10 x 10 m test plots within the study area was positively associated with a high percentage cover of gravel and pebbles as opposed to sand or stones, and with a gentle rise as opposed to a slope in the topography of the plots. A significant association was found between the occurrence of Lithops and Avonia albissima in the test plots suggesting that the latter, which is more visible, can be used as an indicator of Lithops in the field. (C) 2017 SAAB. Published by Elsevier B.V. All rights reserved.
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| 21. |
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| 22. |
- Mujaju, Claid, et al.
(författare)
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Genetic diversity among and within watermelon (Citrullus lanatus) landraces in Southern Africa
- 2011
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Ingår i: Journal of Horticultural Science and Biotechnology. - : Informa UK Limited. - 1462-0316 .- 2380-4084. ; 86, s. 353-358
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Tidskriftsartikel (refereegranskat)abstract
- Genetic diversity in watermelon (Citrullus lanatus) was estimated among 213 seedlings from 22 accessions collected in Botswana, Namibia, South Africa, Zambia, and Zimbabwe. The accessions consisted of two types of watermelon landraces: sweet watermelon (C. lanatus var. lanatus) and cow-melon (C. lanatus var. citroides), also known as citron melon. In addition, three commercial varieties of C. lanatus var. lanatus from the USA were included for comparison. Ten simple sequence repeat (SSR; microsatellite) loci detected a total of 153 alleles. The polymorphic information content (PIC) ranged from 0.833 - 0.963, suggesting sufficient discriminatory power. Both a cluster analysis and a principal co-ordinate analysis produced two major clusters, one with the 13 cow-melon accessions and the other with the 12 sweet watermelon accessions. Within the sweet watermelon cluster, the three US cultivars grouped together with the Botswana accessions. Some of the other accessions also grouped according to their country of origin, but others did not. Within-accession diversity parameters showed that those sweet watermelon accessions found in traditional agrosystems were just as genetically variable as the cow-melon accessions.
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| 23. |
- Mujaju, Claid, et al.
(författare)
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Genetic diversity in watermelon (Citrullus lanatus) landraces from Zimbabwe revealed by RAPD and SSR markers
- 2010
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Ingår i: Hereditas. - : Springer Science and Business Media LLC. - 0018-0661 .- 1601-5223. ; 147, s. 142-153
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Tidskriftsartikel (refereegranskat)abstract
- Low polymorphism in cultivated watermelon has been reported in previous studies, based mainly on US Plant Introductions and watermelon cultivars, most of which were linked to breeding programmes associated with disease resistance. Since germplasm sampled in a putative centre of origin in southern Africa may harbour considerably higher variability, DNA marker-based diversity was estimated among 81 seedlings from eight accessions of watermelon collected in Zimbabwe; five accessions of cow-melons (Citrullus lanatus var. citroides) and three of sweet watermelons (C. lanatus var. lanatus). Two molecular marker methods were used, random amplified polymorphic DNA (RAPD) and simple sequence repeats (SSR) also known as microsatellite DNA. Ten RAPD primers produced 138 markers of which 122 were polymorphic. Nine SSR primer pairs detected a total of 43 alleles with an average of 4.8 alleles per locus. The polymorphic information content (PIC) ranged from 0.47 to 0.77 for the RAPD primers and from 0.39 to 0.97 for the SSR loci. Similarity matrices obtained with SSR and RAPD, respectively, were highly correlated but only RAPD was able to provide each sample with an individual-specific DNA profile. Dendrograms and multidimensional scaling (MDS) produced two major clusters; one with the five cow-melon accessions and the other with the three sweet watermelon accessions. One of the most variable cow-melon accessions took an intermediate position in the MDS analysis, indicating the occurrence of gene flow between the two subspecies. Analysis of molecular variation (AMOVA) attributed most of the variability to within-accessions, and contrary to previous reports, sweet watermelon accessions apparently contain diversity of the same magnitude as the cow-melons.
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| 24. |
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| 25. |
- Mujaju, Claid, et al.
(författare)
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Molecular and farmer-based comparison of a wild-weed and landrace complex of watermelon in Zimbabwe
- 2012
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Ingår i: Australian Journal Of Crop Science. - 1835-2693 .- 1835-2707. ; 6, s. 656-661
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Tidskriftsartikel (refereegranskat)abstract
- Traditional farming systems have been associated with the occurrence of intervarietal and interspecific natural crosses in many crop plants, thus contributing to the genetic diversity of the crop through genetic exchange. In this study, a combination of farmerpreferred morphological traits and RAPD markers were used to evaluate the dynamics of genetic diversity in 43 watermelon accessions collected at a single village level with a traditional farming system. The molecular variability assessed with RAPD markers and analyzed with multidimensional scaling and cluster analysis, demonstrated a substantial differentiation among the accessions. Population structure analysis also demonstrated the existence of three major forms of watermelon, identified by a set of alleles predominant within each form. Dendrograms based on RAPD data and on farmer-preferred traits data were positively correlated according to a Mantel test. Although cultivated cow-melons were genetically most similar to wild-weedy plants at molecular level, they grouped more similar to sweet watermelons based on farmer-preferred traits. The present study revealed limited gene flow between three forms of watermelon and provides insight into how the genetic differentiation corresponds to farmers’ classification of watermelons
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| 26. |
- Mujaju, Claid, et al.
(författare)
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Variationsrika vattenmeloner i södra Afrika
- 2012
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Ingår i: LTJ-fakultetens faktablad.
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Annan publikation (populärvet., debatt m.m.)abstract
- På soliga semesterresor till varmare länder, har allt fler svenskar lärt sig att uppskatta de stora, läskande vattenmelonerna. Ingenting släcker törsten bättre, och säkrare, än en generös skiva saftig vattenmelon med sitt karaktäristiska spröda och rosaröda fruktkött. Tillgången är inget problem; det finns knappast något tropiskt eller subtropiskt land (vattenmelon växer bäst vid 20–30 °C) som inte kan erbjuda lokalodlade vattenmeloner. Minst 55 länder producerar vattenmeloner, och den samlade produktionen beräknas till över 100 millioner ton per år. I odlingsanalyser betraktas vattenmelon som en grönsak, och den odlas på drygt 10% av den areal som används till grönsaker
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| 27. |
- Muzila, Mbaki, et al.
(författare)
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Alteration of neutrophil reactive oxygen species production by extracts of Devil's Claw (Harpagophytum)
- 2016
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Ingår i: Oxidative Medicine and Cellular Longevity. - 1942-0900 .- 1942-0994.
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Tidskriftsartikel (refereegranskat)abstract
- Harpagophytum, Devil's Claw, is a genus of tuberiferous xerophytic plants native to southern Africa. Some of the taxa are appreciated for their medicinal effects and have been traditionally used to relieve symptoms of inflammation. The objectives of this pilot study were to investigate the antioxidant capacity and the content of total phenols, verbascoside, isoverbascoside, and selected iridoids, as well as to investigate the capacity of various Harpagophytum taxa in suppressing respiratory burst in terms of reactive oxygen species produced by human neutrophils challenged with phorbol myristate acetate (PMA), opsonised Staphylococcus aureus, and Fusobacterium nucleatum. Harpagophytum plants were classified into different taxa according to morphology, and DNA analysis was used to confirm the classification. A putative new variety of H. procumbens showed the highest degree of antioxidative capacity. Using PMA, three Harpagophytum taxa showed anti-inflammatory effects with regard to the PBS control. A putative hybrid between H. procumbens and H. zeyheri in contrast showed proinflammatory effect on the response of neutrophils to F. nucleatum in comparison with treatment with vehicle control. Harpagophytum taxa were biochemically very variable and the response in suppressing respiratory burst differed. Further studies with larger number of subjects are needed to corroborate anti-inflammatory effects of different taxa of Harpagophytum.
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| 28. |
- Muzila, Mbaki, et al.
(författare)
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Alteration of Neutrophil Reactive Oxygen Species Production by Extracts of Devil’s Claw (Harpagophytum)
- 2016
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Ingår i: Oxidative Medicine and Cellular Longevity. - : Hindawi Limited. - 1942-0900 .- 1942-0994.
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Tidskriftsartikel (refereegranskat)abstract
- Harpagophytum,Devil’sClaw, is a genus of tuberiferous xerophytic plants native to southernAfrica. Some of the taxa are appreciated for their medicinal effects and have been traditionally used to relieve symptoms of inflammation.The objectives of this pilot study were to investigate the antioxidant capacity and the content of total phenols, verbascoside, isoverbascoside, and selected iridoids, as well as to investigate the capacity of various Harpagophytum taxa in suppressing respiratory burst in terms of reactive oxygen species produced by human neutrophils challenged with phorbol myristate acetate (PMA), opsonised Staphylococcus aureus, and Fusobacterium nucleatum. Harpagophytum plants were classified into different taxa according to morphology, and DNA analysis was used to confirmthe classification. A putative new variety of H. procumbens showed the highest degree of antioxidative capacity. Using PMA, three Harpagophytum taxa showed anti-inflammatory effects with regard to the PBS control. A putative hybrid between H. procumbens and H. zeyheri in contrast showed proinflammatory effect on the response of neutrophils to F. nucleatum in comparison with treatment with vehicle control. Harpagophytum taxa were biochemically very variable and the response in suppressing respiratory burst differed. Further studies with larger number of subjects are needed to corroborate anti-inflammatory effects of different taxa of Harpagophytum.
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| 29. |
- Muzila, Mbaki, et al.
(författare)
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Assessment of diversity in Harpagophytum with RAPD and ISSR markers provides evidence of introgression
- 2014
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Ingår i: Hereditas. - : Springer Science and Business Media LLC. - 0018-0661 .- 1601-5223. ; 151, s. 91-101
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Tidskriftsartikel (refereegranskat)abstract
- The genus Harpagophytumhas two species: H. procumben swhich is an important medicinal plant in southern Africa, and H. zeyheri. Genetic diversity in 96 samples, obtained by germinating seeds collected from Botswana, was assessed using six inter-simple sequence repeat (ISSR) and 10 random amplified polymorphic DNA (RAPD) primers. These DNA markers yielded a total of 138 polymorphic bands. Polymorphism information content (PIC) ranged from 0.06 to 0.39 for ISSR primers, and from 0.09 to 0.43 for RAPD primers. Jaccard's similarity coefficients were highest when seedlings derived from the same fruit capsule were compared, while seedlings from different fruits on the same plant had intermediate values. The lowest values were recorded among seedlings from different plants. These results were consistent with an outcrossing breeding system in Harpagophytum. Analysis of molecular variance revealed significant differentiation (P < 0.01) between taxonomic units within Harpagophytum. About 39% of the variability occurred between the two species, H. procumbens and H. zeyheri. Plants with an intermediate morphology, i.e. putative hybrids (PH), showed 21% differentiation when compared with H. procumbens ssp. procumbens (PP), and 19% when compared with H. procumbens ssp. transvaalense (PT) or with H. zeyheri (ZZ). In addition, a deviating variant of PT was identified, here termed ‘procumbens new variety’ (PN). PN showed only 9% differentiation when compared with PT, 22% when compared with PP or with PH, and 41% when compared with ZZ. Considerable differentiation between the two Harpagophytum species was revealed also by a cluster analysis. Introgression was, however, suggested by the intermediate position of the putative hybrid plants in a principal component analysis while inter-specific gene flow was shown by a Bayesian genetic structure analysis.
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| 30. |
- Muzila, Mbaki, et al.
(författare)
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Djävulsklon från Afrika
- 2016
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Ingår i: LTV-fakultetens faktablad.
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Annan publikation (populärvet., debatt m.m.)abstract
- Nyttjar man naturmedicinska preparat, har man troligen hört talas om djävulsklo från Afrika. I övrigt får denna torrmarksväxt anses tämligen okänd i Sverige. För stora delar av den fattiga befolkningen på landsbygden i Botswana, Namibia och Sydafrika utgör djävulsklo däremot en välkänd och viktig inkomstkälla.
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| 31. |
- Muzila, Mbaki, et al.
(författare)
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Harpagophytum germplasm varies in tuber peel and pulp content of important phenylpropanoids and iridoids
- 2018
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Ingår i: South African Journal of Botany. - : Elsevier BV. - 0254-6299 .- 1727-9321. ; 115, s. 153-160
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Tidskriftsartikel (refereegranskat)abstract
- Tubers of the xerophytic African plant Harpagophytum procumbens are used as an appreciated medicinal drug whereas the value of H. zeyheri remains uncertain. Due to large and sometimes continuous morphological variation, discrimination between these two species can be difficult. In addition, interspecific hybridization may occur and could further complicate the collection of proper plant material for medicinal purposes. Hence the objectives of this study were to 1) study the content of selected secondary metabolites in peel and pulp of Harpagophytum tubers of different taxa, 2) identify possible species-specific differences in content (profile and amount) of selected secondary metabolites, and 3) investigate associations between content of selected secondary metabolites and sample origin. Although composition and content of the studied compounds varied among populations within species, H. procumbens and H. zeyheri had significantly different phytochemical profiles, with putative hybrids sometimes being intermediate and sometimes transgressive. In both peel and pulp the content of isoverbascoside, verbascoside, acetylacteoside and pagoside were higher in putative hybrids and H. procumbens compared with H. zeyheri. The content of the main bioactive compound harpagoside was significantly higher in H. procumbens compared with putative hybrids and H. zeyheri, with both pulp and peel content of H. procumbens being approximately twice as high as the pulp and peel content of putative hybrids. Accurate identification, selection andmultiplication of germplasm with superior qualities should therefore be performed to provide plant material with a high content of bioactive compounds. (c) 2018 SAAB. Published by Elsevier B.V. All rights reserved.
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| 32. |
- Nybom, Hilde
(författare)
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75-årsjubileum på Balsgård
- 2017
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Ingår i: Pomologen. - 1650-9455. ; 17, s. 20-27
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 33. |
- Nybom, Hilde
(författare)
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Advances in understanding texture development in apples
- 2023
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Ingår i: Improving the quality of apples. - 9781801463218
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Bokkapitel (refereegranskat)abstract
- This chapter reviews advances in understanding texture development in apples. It starts by first describing the anatomy and physiology of fruit texture traits. This is then followed by an evaluation of fruit texture parameters. The chapter goes on to discuss the influence of growing conditions, the effects of storage conditions on fruit texture as well as the impact fungal diseases can have on fruit texture. A section on genetic determination of texture is also provided, followed by a review of the association between texture and aroma, as well as an overview of selection/breeding achievements.
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| 34. |
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| 35. |
- Nybom, Hilde, et al.
(författare)
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Analysis of the genetic diversity and structure across a wide range of germplasm reveals prominent gene flow in apple at the European level
- 2016
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Ingår i: BMC Plant Biology. - : Springer Science and Business Media LLC. - 1471-2229. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- Background: The amount and structure of genetic diversity in dessert apple germplasm conserved at a European level is mostly unknown, since all diversity studies conducted in Europe until now have been performed on regional or national collections. Here, we applied a common set of 16 SSR markers to genotype more than 2,400 accessions across 14 collections representing three broad European geographic regions (North + East, West and South) with the aim to analyze the extent, distribution and structure of variation in the apple genetic resources in Europe.Results: A Bayesian model-based clustering approach showed that diversity was organized in three groups, although these were only moderately differentiated (F-ST = 0.031). A nested Bayesian clustering approach allowed identification of subgroups which revealed internal patterns of substructure within the groups, allowing a finer delineation of the variation into eight subgroups (F-ST = 0.044). The first level of stratification revealed an asymmetric division of the germplasm among the three groups, and a clear association was found with the geographical regions of origin of the cultivars. The substructure revealed clear partitioning of genetic groups among countries, but also interesting associations between subgroups and breeding purposes of recent cultivars or particular usage such as cider production. Additional parentage analyses allowed us to identify both putative parents of more than 40 old and/or local cultivars giving interesting insights in the pedigree of some emblematic cultivars.Conclusions: The variation found at group and subgroup levels may reflect a combination of historical processes of migration/selection and adaptive factors to diverse agricultural environments that, together with genetic drift, have resulted in extensive genetic variation but limited population structure. The European dessert apple germplasm represents an important source of genetic diversity with a strong historical and patrimonial value. The present work thus constitutes a decisive step in the field of conservation genetics. Moreover, the obtained data can be used for defining a European apple core collection useful for further identification of genomic regions associated with commercially important horticultural traits in apple through genome-wide association studies.
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| 36. |
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| 37. |
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| 38. |
- Nybom, Hilde, et al.
(författare)
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Assessment of fire blight tolerance in apple based on plant inoculations with Erwinia amylovora and DNA markers
- 2012
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Ingår i: Trees - Structure and Function. - : Springer Science and Business Media LLC. - 0931-1890 .- 1432-2285. ; 26, s. 199-213
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Tidskriftsartikel (refereegranskat)abstract
- Fire blight (Erwinia amylovora) causes serious damage to pome fruit orchards, and identification of germplasm with heritable disease resistance is therefore crucial. Two dominant SCAR (sequence characterised amplified region) marker alleles (AE10-375 and GE-8019), flanking a previously identified QTL (quantitative trait locus) for resistance to fire blight on ‘Fiesta’ linkage group 7 in apple cultivars related to ‘Cox’s Orange Pippin’, were screened on 205 apple cultivars. Both marker alleles were present in 22% of the cultivars, indicating presence of the QTL allele for tolerance, and both were lacking in 25%, indicating homozygosity for absence of the QTL tolerance allele. However, 33% had only the marker allele AE10-375, while 20% had only GE-8019, suggesting that some cultivars with the dominant alleles for both of the flanking markers can carry these on separate chromosomes and may lack the QTL allele for tolerance. In 2009 and 2010, terminal shoots of greenhouse-grown grafted trees of 21 cultivars (only 20 in 2010) were inoculated with Erwinia amylovora. ‘Idared’ (susceptible) and ‘Enterprise’ (tolerant) were included as controls. Disease severity for each cultivar was expressed as percentage of necrosis in relation to entire length of shoot, and the ranking of cultivars in 2009 and 2010 was compared with a Spearman rank correlation test,P<0.01. A relationship between presence of both flanking marker alleles for tolerance and level of fire blight tolerance was confirmed with a Mann–Whitney U-test,P<0.01 in 2009, andP<0.05 in 2010. A PCO (principal coordinate) analysis based on band profiles obtained with 12 SSR (simple sequence repeat) loci produced three loose clusters, two of which contained known offspring of ‘Cox’s Orange Pippin’, and one with cultivars that were either unrelated or had an unknown origin. Cases where DNA markers did not predict level of fire blight damage as expected, were, however, as common among descendants of ‘Cox’s Orange Pippin’ as among apparently unrelated cultivars. Obviously the ‘Fiesta’ LG 7 QTL has some predictive value, both for known ‘Cox’ relatives and others, but more efficient markers would be desirable for marker-assisted selection.
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| 39. |
- Nybom, Hilde
(författare)
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Association between blue mold resistance and qPCR-based molecular markers in apple
- 2020
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Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; , s. 277–283-
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Konferensbidrag (refereegranskat)abstract
- Apple cultivars vary in their susceptibility to Penicillium expansum, the causal agent of blue mold, which is one of the most devastating storage diseases in this crop. The genetic background to susceptibility/resistance has not yet been fully clarified, but significant associations have been detected between 1) the size of lesions caused by blue mold after artificial inoculation of harvested fruit, and 2) various fruit texture-related traits (e.g., fruit firmness at harvest and rate of fruit softening during storage) as well as 3) fruit biochemical contents (e.g., polyphenols). In the present study, 82 apple cultivars were phenotyped for fruit firmness, fruit softening rate and size of blue mold lesions after wound inoculation of newly harvested fruit with P. expansum spores. These cultivars were screened using 15 qPCR-based molecular markers targeting loci linked to fruit texture and chemical composition on apple linkage groups (LG) 10 and 16. The results revealed significant phenotype-genotype associations between two loci on LG 16 (ss475881696 and ss475882555) and lesion decay (p=0.047 and 0.037, respectively). In addition, a non-significant relationship (p=0.08) between softening rate and two fruit acidity-related loci on LG 16, ss475876558 and Ma1-SNP1455, was indicated. These results will be useful in further investigations of key genes for blue mold resistance, and for developing markers that can be applied in apple breeding programs.
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| 40. |
- Nybom, Hilde, et al.
(författare)
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Beauty Is as Beauty Does - Culinary and Medicinal Use of Rosehips
- 2015
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Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 1064, s. 137-150
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Konferensbidrag (refereegranskat)abstract
- The ornamental value of the rose flower is well-known, but rose plants have long been appreciated also for their fruits, the rosehips. These rosehips are sometimes harvested from cultivated or, more commonly, wild or naturalized stands to produce juice, dessert soup, jelly and other tasty products. Rosehips of especially the dogroses, i.e., Rosa sect. Caninae, have recently enjoyed a renewed interest due to their very high levels of antioxidant compounds, mainly polyphenols, but also carotenoids and vitamins B, C and E. Other important rosehip-producing species are found in sections Rosa and Gallicanae, as well as R. roxburghii in subgenus Platyrhodon. Medicinal preparations are presently produced and marketed for the treatment of, e.g., osteoarthritis and various stomach problems. The seeds contain high contents of unsaturated fatty acids, which are used for production of oils for skin treatment and as cosmetics. The amount and composition of bioactive compounds in rosehips vary greatly with genotype and environment. Breeding of improved dogrose genotypes or of intersectional hybrids is, however, complicated by the unique canina meiosis, resulting in widely different offspring in reciprocal crosses, and occasionally also producing offspring by apomixis.
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| 41. |
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| 42. |
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| 43. |
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| 44. |
- Nybom, Hilde
(författare)
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Combining genetic resources and elite material populations to improve the accuracy of genomic prediction in apple
- 2022
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Ingår i: G3. - : Oxford University Press (OUP). - 2160-1836. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Genomic selection is an attractive strategy for apple breeding that could reduce the length of breeding cycles. A possible limitation to the practical implementation of this approach lies in the creation of a training set large and diverse enough to ensure accurate predictions. In this study, we investigated the potential of combining two available populations, i.e., genetic resources and elite material, in order to obtain a large training set with a high genetic diversity. We compared the predictive ability of genomic predictions within-population, across-population or when combining both populations, and tested a model accounting for population-specific marker effects in this last case. The obtained predictive abilities were moderate to high according to the studied trait and small increases in predictive ability could be obtained for some traits when the two populations were combined into a unique training set. We also investigated the potential of such a training set to predict hybrids resulting from crosses between the two populations, with a focus on the method to design the training set and the best proportion of each population to optimize predictions. The measured predictive abilities were very similar for all the proportions, except for the extreme cases where only one of the two populations was used in the training set, in which case predictive abilities could be lower than when using both populations. Using an optimization algorithm to choose the genotypes in the training set also led to higher predictive abilities than when the genotypes were chosen at random. Our results provide guidelines to initiate breeding programs that use genomic selection when the implementation of the training set is a limitation.
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| 45. |
- Nybom, Hilde, et al.
(författare)
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Den skånska äpplemustens terroir
- 2015
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Ingår i: LTV-fakultetens faktablad.
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Annan publikation (populärvet., debatt m.m.)abstract
- Idag ser vi ett kraftigt ökande intresse för lokalproducerad mat och dryck. Många konsumenter lägger stor vikt vid vad de konsumerar, varifrån livsmedlen kommer och hur de produceras. I vinsammanhang har man under lång tid använt sig av begreppet terroir för att sammanfatta lokalitetens betydelse för såväl upplevda som mätbara egenskaper. Något motsvarande har inte hittills dokumenterats för svenska äpplen – den viktigaste råvaran för must i Sverige. Finns det något samband mellan var frukten har odlats och mustens kvalitetsegenskaper? Kan konsumenter känna skillnad mellan must från olika odlingar men av samma sort? Hur kan detta kommuniceras? Detta var huvudfrågeställningarna i en pilotstudie vi nyligen genomförde tillsammans med skånska äppelodlare och musterier.
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| 46. |
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| 47. |
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| 48. |
- Nybom, Hilde
(författare)
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DNA fingerprinting
- 2017
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Ingår i: Reference Module in Life Sciences. - 9780128096338
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Bokkapitel (refereegranskat)
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| 49. |
- Nybom, Hilde
(författare)
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DNA fingerprinting in botany: past, present and future
- 2014
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Ingår i: Investigative Genetics. - : Springer Science and Business Media LLC. - 2041-2223. ; 5
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Forskningsöversikt (refereegranskat)abstract
- Almost three decades ago Alec Jeffreys published his seminal Nature papers on the use of minisatellite probes for DNA fingerprinting of humans (Jeffreys et al. 1985a,b). The new technology was soon adopted for many other organisms including plants, and when Hilde Nybom, Kurt Weising and Alec Jeffreys first met at the very First International Conference on DNA Fingerprinting in Berne, Switzerland in 1990, everybody was enthusiastic about the novel method that allowed us for the first time to discriminate between humans, animals, plants and fungi on the individual level using DNA markers. A newsletter coined “Fingerprint News” was launched, T-shirts were sold, and the proceedings of the Berne conference filled a first book on “DNA fingerprinting: approaches and applications”. Four more conferences were about to follow, one on each continent, and Alec Jeffreys of course was invited to all of them. Since these early days, methodologies have undergone a rapid evolution and diversification. A multitude of techniques have been developed, optimized, and eventually abandoned when novel and more efficient and/or more reliable methods appeared. Despite some overlap between the lifetimes of the different technologies, three phases can be defined that coincide with major technological advances. Whereas the first phase of DNA fingerprinting (“the past”) was dominated by restriction fragment analysis in conjunction with Southern blot hybridization, the advent of the polymerase chain reaction (PCR) in the late 1980s gave way to the development of PCR-based single- or multilocus profiling techniques in the second phase. Given that many routine applications of DNA fingerprinting still rely on PCR-based markers, we here refer to these methods as “DNA fingerprinting in the present”, and include numerous examples in the present review. The beginning of the third phase actually dates back to 2005, when several novel, highly parallel DNA sequencing strategies were developed that increased the throughput over current Sanger sequencing technology 1000-fold and more. High-speed DNA sequencing was soon also exploited for DNA fingerprinting in plants, either in terms of facilitated marker development, or directly in the sense of “genotyping-by-sequencing”. Whereas these novel approaches are applied at an ever increasing rate also in non-model species, they are still far from routine, and we therefore treat them here as “DNA fingerprinting in the future”.
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| 50. |
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