| 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
(författare)
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Genetic variation in resistance to fungal storage diseases in apple : inoculation-based screening, transcriptomics and biochemistry
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Apple is one of the economically and culturally most important fruit crops and has many health-related benefits. Apple production is, however, sensitive to several fungal diseases including blue mold, caused by Penicillium expansum. Problems are more pronounced in organic production or in countries where postharvest application of fungicides is prohibited. To limit or overcome this problem, many studies have been focused on investigations of the mechanism of resistance/tolerance. No major gene(s) have as yet been identified, but quantitatively inherited traits, some of which are related to fruit texture and content of chemical compounds, have been shown to affect the ability of cultivars to withstand storage diseases. In the present thesis, inter-cultivar variation in terms of resistance to fungal storage diseases was investigated at two locations, i.e. Balsgård in Sweden and Njøs in Norway. The association of harvest date, fruit firmness and softening with lesion decay was investigated on large sets of cultivars. The contribution of four fruit texture-related genes (Md-ACO1, Md-ACS1, Md-Exp7 and Md-PG1) in explaining the fruit texture characteristics was examined. Fruit content of chemical compounds with a potential impact on disease resistance was also investigated, and finally the regulation of apple genes upon fungal infection was studied in order to identify candidate genes responsible for disease resistance. Inoculation-based screening indicated large variation across the investigated cultivars in terms of blue mold and bitter rot susceptibility. Harvest date and softening rate of fruits during storage had a large impact on resistance to fungal diseases, thus cultivars with moderate to firm fruits that soften comparatively little during storage could withstand the fungal infection comparatively well. Softening rate is, in its turn, closely associated with harvest date whereas four fruit texture-related genes had lower predictive power than expected. Quantifying the chemical compounds in the fruit samples revealed that some of these compounds, especially flavonols and procyanidin B2, could contribute to resistance against blue mold, whereas contents of malic acids or total titratable acidity had considerably less impact. Differential expression of FLS, LDOX, and CHS genes involved in biosynthesis of flavonoids and PGIP, TT10, WAK1 and CTL1 genes related to cell wall structure indicate the importance of fruit characteristics and biochemical compounds in the resistance mechanism.
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| 3. |
- 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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| 4. |
- 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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| 5. |
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| 6. |
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| 7. |
- 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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| 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. |
- Nybom, Hilde, et al.
(författare)
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DNA marker-assisted evaluation of fruit firmness at harvest and post-harvest fruit softening in a diverse apple germplasm
- 2013
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Ingår i: Tree Genetics and Genomes. - : Springer Science and Business Media LLC. - 1614-2942 .- 1614-2950. ; 9, s. 279-290
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Tidskriftsartikel (refereegranskat)abstract
- Several different genes have been proposed as responsible for fruit texture variability at harvest and/or after storage. We have analysed 127 apple cultivars for allelic composition in two key genes that are directly involved in the ethylene biosynthesis pathway, Md-ACS1 and Md-ACO1, and two other genes that are involved in cell wall degradation, Md-Exp7 and Md-PG1. Firmness was measured with a penetrometer at harvest and after 6 or 12 weeks (early- and late-maturing cultivars, respectively) of cold storage. Maturation time was positively correlated with firmness at harvest and negatively correlated with fruit softening rate (difference between firmness at harvest and after storage, divided by number of weeks in storage). Polyploid cultivars showed significantly higher firmness at harvest compared to diploids. Alleles previously described as responsible for good texture were associated with significantly lower softening for Md-ACS1 and Md-PG1, but the opposite was noted for Md-EXP7. Results were nonsignificant for Md-ACO1. Allele frequencies were very uneven in all four loci, with the three most common multi-locus configurations accounting for 64 % of the entire material. The predictive power of these genes was calculated with a partial least squares discriminant analysis, and these accounted for 15 % of the observed variation in initial firmness and 18 % for softening rate. Inclusion of maturation time, storage time (i.e. 6 or 12 weeks) and initial firmness into the model however increased the predictability of softening rate to 38 %. Dividing the material in modern (released after 1960) and old cultivars did not change the outcome of our analyses.
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| 10. |
- Nybom, Hilde, et al.
(författare)
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European pome fruit genetic resources evaluated for disease resistance
- 2012
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Ingår i: Trees - Structure and Function. - : Springer Science and Business Media LLC. - 0931-1890 .- 1432-2285. ; 26, s. 179-189
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Forskningsöversikt (refereegranskat)abstract
- Pome fruit genetic resources collections constitute a highly valuable resource not only for fruit breeding but also for direct use by nurseries, growers, and home gardeners. In order to use these resources efficiently and sustainably, reliable evaluation data on fruit and tree characteristics must be generated. Here we focus on pome fruit genetic resources evaluated phenotypically and genotypically for susceptibility to apple scab (Venturiainaequalis), powdery mildew (Podosphaeraleucotricha), fire blight (Erwiniaamylovora), pear rust (Gymnosporangiumsabinae) and storage diseases (e.g.,Penicilliumexpansum). Examples are presented of several ongoing projects throughout Europe, with the aim to evaluate fruit genetic resources for disease susceptibility and potential use in breeding and for commercial use. The COST action 864 has fostered international cooperation in the evaluation of pome fruit genetic resources, and some of these evaluations therefore involve research groups from several of the participating countries.
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| 11. |
- 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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| 12. |
- Nybom, Hilde, et al.
(författare)
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Pre-breeding for future challenges in Nordic apples: susceptibility to fruit tree canker and storage diseases
- 2016
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Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 1127, s. 117-124
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Apple production has a long history in the Nordic countries, but high labour costs and challenging climatic conditions result in production costs that are not competitive on the international market. In addition, access to permitted pre‐harvest chemicals in the orchards has been severely restricted in recent years, and post‐ harvest applications are completely banned. Moreover, grower economy would benefit from being able to forego chemical fungicides altogether, as there is an increasing demand for locally produced, organic fruit. Consequently, climate adaptation and disease resistance/tolerance are major issues for apple breeding programmes in Norway, Sweden and Finland. A public‐private partnership project initiated by the Nordic Council of Ministers and administered by NordGen started in 2012 with the aim of producing and disseminating knowledge concerning levels of susceptibility against some of the most devastating apple diseases in the Nordic countries, namely fruit tree canker (Neonectria ditissima) and storage diseases (Neofabraea spp. and Penicillium expansum), in apple cultivars of potential interest for plant breeding and cultivar development in the Nordic countries. Inoculation of fruit of 81 different apple cultivars with blue mould, P. expansum, has been carried out in Norway and Sweden, whereas evaluation of spontaneous infections of various fungi during storage has been carried out in Finland using fruit of organically produced, local apple cultivars. For fruit tree canker, inoculations have been carried out on detached shoots of 50 different apple cultivars in Norway and Sweden. For both apple canker and blue mould, reproducibility among years and sites was sufficiently high to enable an approximate determination of the level of susceptibility of the studied cultivars.
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| 13. |
- 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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| 14. |
- Nybom, Hilde, et al.
(författare)
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Review of the Impact of Apple Fruit Ripening, Texture and Chemical Contents on Genetically Determined Susceptibility to Storage Rots
- 2020
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Ingår i: Plants. - : MDPI AG. - 2223-7747. ; 9
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Forskningsöversikt (refereegranskat)abstract
- Fungal storage rots like blue mould, grey mould, bull's eye rot, bitter rot and brown rot destroy large amounts of the harvested apple crop around the world. Application of fungicides is nowadays severely restricted in many countries and production systems, and these problems are therefore likely to increase. Considerable variation among apple cultivars in resistance/susceptibility has been reported, suggesting that efficient defence mechanisms can be selected for and used in plant breeding. These are, however, likely to vary between pathogens, since some fungi are mainly wound-mediated while others attack through lenticels or by infecting blossoms. Since mature fruits are considerably more susceptible than immature fruits, mechanisms involving fruit-ripening processes are likely to play an important role. Significant associations have been detected between the susceptibility to rots in harvested fruit and various fruit maturation-related traits like ripening time, fruit firmness at harvest and rate of fruit softening during storage, as well as fruit biochemical contents like acidity, sugars and polyphenols. Some sources of resistance to blue mould have been described, but more research is needed on the development of spore inoculation methods that produce reproducible data and can be used for large screenings, especially for lenticel-infecting fungi.
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| 15. |
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| 16. |
- Nybom, Hilde, et al.
(författare)
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Vi vill ha krasigare äpplen!
- 2012
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Ingår i: LTJ-fakultetens faktablad.
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Annan publikation (populärvet., debatt m.m.)abstract
- Äpple är gott – men inte alltid! Dagens konsumenter är kräsna och vet precis hur dom vill ha det: äpplet ska vara både fast och krasigt på samma gång. Det ska knastra rejält mellan tänderna när man tar en tugga. Vissa minns kanske mormors gamla träd av Sävstaholm och andra klassiker, men om de erbjuds lagrade äpplen av dessa sorter blir domen inte nådig: frukten är ju alldeles för mjuk och mjölig! Går inte att äta!
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| 17. |
- Tahir, Ibrahim, et al.
(författare)
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Rye Bran Alkylresorcinols Inhibit Growth of Penicillium expansum and Neofabraea perennans In Vitro and In Vivo on Different Apple Cultivars
- 2014
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Ingår i: European Journal of Horticultural Science. - 1611-4434 .- 1611-4426. ; 79:4, s. 218-225
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Tidskriftsartikel (refereegranskat)abstract
- Apples (Malus domestica Borkh.) are highly susceptible to fungi causing rots, especially in organic orchards where these rots cause major economic losses. Since the use of conventional fungicides is prohibited or restricted in many countries and in organic production, altogether, one alternative is to make use of bioactive compounds that can inhibit fungal growth on apples. Antifungal effects of alkylresorcinols (ARs), isolated from rye bran, were used in two different bioactive emulsions and tested in vitro as well as in vivo against two fungi, Penicillium expansum and Neofabraea perennans, which cause important storage diseases in apple. For both fungi, application of AR emulsions produced a 50 % reduction in mycelial growth and spore germination. The in vivo tests were carried out on wound-inoculated fruit of four apple cultivars, 'Aroma', 'Ingrid Marie', Frida' and 'Gloster'. Spraying the inoculated fruit with ARs decreased lesion area diameter caused by P. expansum with 17-52 % and lesion area diameter caused by N. perennans with 31-77 %, depending on the apple cultivar. For each fungus, the inhibitory effect of ARs was stronger in those apple cultivars that appear to have the highest level of disease tolerance, i.e. the smallest lesions on the control fruit. The level of sun exposure of the fruit had neither significant influence on the decay nor in the inhibitory effect obtained with the postharvest application of ARs.
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| 18. |
- Tahir, Ibrahim, et al.
(författare)
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Susceptibility to blue mold caused by Penicillium expansum in apple cultivars adapted to a cool climate
- 2015
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Ingår i: European Journal of Horticultural Science. - 1611-4426 .- 1611-4434. ; 80, s. 117-127
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Tidskriftsartikel (refereegranskat)abstract
- Each year, fungal storage rots cause serious losses in the apple industry. The problem is especially prominent in production systems with little or no use of pre- or postharvest fungicides. Consequently, a high level of tolerance to storage rots is very desirable. A set of 81 apple cultivars were studied in two different production areas (Njos in Norway and Balsgard in Sweden), during two seasons (2012 and 2013), to investigate genetically determined susceptibility to blue mold, Penicillium expansum. Lesion diameter, measured on symptoms developing after artificial inoculation with this pathogen and cold storage for 6-12 weeks, and decay index, calculated as lesion diameter divided by number of weeks in storage, varied significantly among cultivars. Associations between disease evaluation data and different fruit characteristics were also investigated. Decay index was negatively correlated with harvest date, estimated as number of days since full bloom, and fruit firmness at harvest. A positive correlation was instead found between decay index and amount of fruit softening during storage. These results provide data about genetically determined level of resistance to blue mold for apple cultivars adapted to a cool climate, and will be valuable for further research on the genetic control of resistance, as well as for choice of breeding material.
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