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Genetic variation in resistance to fungal storage diseases in apple

inoculation-based screening, transcriptomics and biochemistry

Ahmadi-Afzadi, Masoud (2015). Genetic variation in resistance to fungal storage diseases in apple. Diss. (sammanfattning/summary) Alnarp : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2015:18
ISBN 978-91-576-8234-5
eISBN 978-91-576-8235-2
[Doctoral thesis]

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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.

Authors/Creators:Ahmadi-Afzadi, Masoud
Title:Genetic variation in resistance to fungal storage diseases in apple
Subtitle:inoculation-based screening, transcriptomics and biochemistry
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :February 2015
Depositing date:18 February 2015
Number of Pages:69
IKellerhals M., Szalatnay D., Hunziker K., Duffy B., Nybom H., Ahmadi- Afzadi M., Höfer M., Richter K. and Lateur M. (2012). European pome fruit genetic resources evaluated for disease resistance. Trees. 26: 179-189.
IINybom H., Ahmadi-Afzadi M., Sehic J. and Hertog M. (2013). DNA marker-assisted evaluation of fruit firmness at harvest and post-harvest fruit softening in a diverse apple germplasm. Tree Genet. Genomes. 9: 279-290.
IIIAhmadi-Afzadi M., Tahir I. and Nybom H. (2013). Impact of harvesting time and fruit firmness on the tolerance to fungal storage diseases in an apple germplasm collection. Postharvest Biol. Tec. 82: 51-58.
IVTahir I., Nybom H., Ahmadi-Afzadi M., Røen K., Sehic J. and Røen D. Susceptibility to blue mold caused by Penicillium expansum in apple cultivars adapted to a cool climate. Eur. J. Hortic. Sci., in press.
VAhmadi-Afzadi M., Nybom H., Ekholm A., Tahir I. and Rumpunen K. Biochemical contents of apple peel and flesh affect level of partial resistance to blue mold. (Manuscript)
VIAhmadi-Afzadi M., Nybom H., Orsel M., Pelletier S., Bruneau M., Proux-Wéra E. and Renou J.P. Gene expression analysis of resistant and susceptible apple cultivars challenged with Penicillium expansum using an oligonucleotide microarray. (Manuscript)
Place of Publication:Alnarp
Publisher:Department of Plant Breeding, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-576-8234-5
ISBN for electronic version:978-91-576-8235-2
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:F Plant production > F30 Plant genetics and breeding
H Protection of plants and stored products > H20 Plant diseases
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Horticulture
(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 404 Agricultural Biotechnology > Plant Biotechnology
(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 404 Agricultural Biotechnology > Genetics and Breeding
Agrovoc terms:malus, apples, varieties, fungal diseases, moulds, penicillium expansum, disease resistance, defence mechanisms, genes, cell walls, harvesting date, chemical composition, phenolic compounds
Keywords:cell wall, chemical contents, defense mechanism, fruit firmness, gene expression, microarray, polyphenols, qRT-PCR, quercetin
Permanent URL:
ID Code:11903
Faculty:LTV - Fakulteten för landskapsarkitektur, trädgårds- och växtproduktionsvetenskap
Department:(LTJ, LTV) > Department of Plant Breeding (from 130101)
Deposited By: Mr. Masoud Ahmadi Afzadi
Deposited On:19 Feb 2015 14:13
Metadata Last Modified:10 Sep 2020 13:41

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