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Resistance to early blight in potato and genetic structure of the pathogen population in Southeast Sweden

Odilbekov, Firuz (2015). Resistance to early blight in potato and genetic structure of the pathogen population in Southeast Sweden. Diss. (sammanfattning/summary) Alnarp : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae, 1652-6880
ISBN 978-91-576-8392-2
eISBN 978-91-576-8393-9
[Doctoral thesis]

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Abstract

Potato early blight caused by the necrotrophic fungus Alternaria solani is a common foliar disease in many potato-growing regions. Application of fungicides is commonly used to effectively control the disease, although they are undesirable due to environmental consequences. Use of resistant cultivars would be the most optimal solution, but there are no cultivars with high level of resistance available on the market. In the present thesis, assessments of early blight resistance both in leaves and tubers of potato cultivars/clones were performed by applying different screening methods (field and greenhouse). Plant defence signalling in response to A. solani infection with main emphasis on salicylic (SA) and jasmonic acid (JA) hormones, was also studied. Furthermore, the genetic variability in A. solani populations from different potato growing regions of southeast Sweden was investigated. The fungal isolates were analysed for the F129L substitutions, which are associated with loss of sensitivity to QoI fungicides. In addition, field experiments were conducted to determine the occurrence of the F129L substitution and genetic shifts in the population during one growing season in response to two different fungicide strategies.

Cultivars/clones revealed significant differences in resistance to A. solani both in leaves and tubers irrespective of screening method. Results from field and intact plant inoculation experiments were significantly correlated but there were no correlations observed between these two methods and detached leaf assays. Some cultivars/clones showed relatively higher level of resistance to the pathogen. Results from the data suggested that SA appears to be responsible for regulating symptom development while JA dependent COI1 defense signaling is important to inhibit fungal growth during early stages of infection. Microarray analysis showed rapid defense responses to A. solani infection mediated by partially overlapping SA and COI1 dependent jasmonic acid (JA) signaling. It was also observed that JA/ethylene signaling responses dominate at later time points.

The genetic variability was relatively high among isolates of A. solani and significant genetic differentiation was found among populations from different locations in southeast Sweden. Two mitochondrial genotypes (GI and GII) were found among the isolates but the F129L substitution was only detected in GII isolates. Results from the field experiment showed that application of azoxystrobin (QoI fungicide) alone did not control the disease; better disease control was achieved with boscalid combined with pyraclostrobin. Similar results were obtained for yield. Moreover, results of sensitivity tests showed that isolates with the F129L substitution were less sensitive to azoxystrobin. AFLP analysis indicated within season changes in the A.solani population, especially at the end of the season.

Authors/Creators:Odilbekov, Firuz
Title:Resistance to early blight in potato and genetic structure of the pathogen population in Southeast Sweden
Series/Journal:Acta Universitatis agriculturae Sueciae (1652-6880)
Year of publishing :21 September 2015
Depositing date:2015
Number of Pages:46
Papers/manuscripts:
NumberReferences
IOdilbekov, F., Carlson-Nilsson, U. & Liljeroth, E. (2014). Phenotyping early blight resistance in potato cultivars and breeding clones. Euphytica, 197(1), pp. 87-97.
IIOdilbekov, F. & Liljeroth, E. Evaluation of foliar and tuber resistance to early blight in a (tetraploid) crossing population of potato (Manuscript).
IIIOdilbekov, F., Burra, D.D., Rosahl, S., Hedley, P.E., Morris, J., Ziegler, J., Liljeroth, E. & Andreasson, E. Positive role of SA and JA mediated COI1 signalling in early response to Alternaria solani in potato (Manuscript).
IVOdilbekov, F., Edin, E., Garkava Gustavsson, L., Persson Hovmalm. H. & Liljeroth, E. Genetic diversity and occurrence of the F129L and G143A substitutions among isolates of Alternaria solani and Alternaria alternata in southeast Sweden (Manuscript).
VOdilbekov, F., Edin, E. & Liljeroth, E. Within season changes in Alternaria solani populations in potato as response to fungicide application strategies (Manuscript).
Place of Publication:Alnarp
Publisher:Department of Plant Protection Biology, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-576-8392-2
ISBN for electronic version:978-91-576-8393-9
ISSN:1652-6880
Language:English
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 > Agricultural Science
Agrovoc terms:solanum tuberosum, fungal diseases, blight, alternaria solani, disease resistance, defence mechanisms, genetic structures, genetic variation, fungicides, salicylic acids, jasmonic acid, field experimentation, sweden
Keywords:Alternaria solani, field trial, resistance, genetic diversity, F129L substitution, QoI fungicides, salicylic acid, jasmonic acid, microarray analysis
URN:NBN:urn:nbn:se:slu:epsilon-e-2945
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-2945
ID Code:12623
Faculty:LTV - Fakulteten för landskapsarkitektur, trädgårds- och växtproduktionsvetenskap
Department:(LTJ, LTV) > Department of Plant Protection Biology
Deposited By: Mr Firuz Odilbekov
Deposited On:21 Sep 2015 08:58
Metadata Last Modified:22 Sep 2015 10:10

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