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| 2. |
- 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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| 3. |
- Nybom, Hilde, et al.
(författare)
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Nordiska äpplen – projekt NordApp
- 2015
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Ingår i: LTV-fakultetens faktablad.
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Annan publikation (populärvet., debatt m.m.)abstract
- Frukt av många olika slag odlas över hela världen, och utgör en viktig del av den totala livsmedelsförsörjningen. I varmare länder är mångfalden stor – former och färger bildar en förförande palett om man besöker en fruktmarknad, liksom doft och smak hos de frukter man väljer att bekanta sig närmare med. I de nordiska länderna sätter klimatet dessvärre stopp för merparten av dessa frukter – men vi har lyckligtvis några, främst kärn- och stenfrukter inom familjen Rosaceae. Äpple har sålunda odlats i de nordiska länderna sedan början av medeltiden, och detta är numera vår i särklass viktigaste frukt, såväl kulturellt som ekonomiskt. Vissa utländska äpplesorter fungerar ganska bra i odling även på våra breddgrader men för merparten blir den korta vegetationsperioden och de stränga vintrarna övermäktiga hinder. Offentligt finansierade växtförädlingsprogram har därför bedrivits i Finland, Norge och Sverige för att ta fram klimatanpassade sorter. På senare tid har ökad omsorg om miljö och hälsa aktualiserat ytterligare ett förädlingsmål: resistens mot olika skadegörare.
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| 4. |
- Nybom, Hilde, et al.
(författare)
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Resistens mot grönmögel hos äpple
- 2015
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Ingår i: LTV-fakultetens faktablad.
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Annan publikation (populärvet., debatt m.m.)abstract
- Äpple är gott och nyttigt, och allt fler konsumenter frågar efter svensk frukt i affärerna. Men tillgången är inte så stor eftersom svenska odlare endast producerar 20% av de äpplen vi äter i Sverige. Resten importeras från utlandet, där klimatet är gynnsammare, arbetskostnaderna lägre och tillgången på tillåtna växtskyddsmedel större. Konsumenterna är kanske beredda att betala lite extra för svensk frukt men man förväntar sig då att kvaliteten ska vara på topp: vackra, friska och välsmakande frukter!
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| 5. |
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| 6. |
- 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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| 7. |
- 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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| 8. |
- 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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| 9. |
- 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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| 10. |
- Nybom, Hilde
(författare)
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Förädlade björnbär
- 2013
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Ingår i: Pomologen. - 1650-9455. ; 13, s. 4-9
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Solmogna björnbär tillhör ju det godaste man kan äta, men buskarna växer tyvärr ofta i hagar med diverse behornade kreatur, och de eftertraktade bären skyddas dessutom av sylvassa taggar (egentligen tornar om man ska vara botaniskt korrekt). Minst 400 björnbärssorter, varav många taggfria (!) och avsedda för odling på fält eller i privatträdgårdar, har därför tagits fram under 100 år av björnbärsförädling runt om i världen. Många av dessa sorter är ganska frostkänsliga, och hittills har därför bara ett fåtal odlats i Sverige, och då mest i landets sydligare delar. På Balsgård framställdes på 1990-talet den storfruktiga och taggfria sorten ‘Douglas’, som såg väldigt lovande ut i de inledande testodlingarna. Tyvärr dog många plantor under följande, kallare vintrar, och marknadsföringen av sorten avbröts.
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