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Population structure and pathogenicity evolution of Phytophthora infestans affects epidemiology and management of late blight disease

Njoroge, Anne (2019). Population structure and pathogenicity evolution of Phytophthora infestans affects epidemiology and management of late blight disease. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2019:14
ISBN 978-91-7760-346-7
eISBN 978-91-7760-347-4
[Doctoral thesis]

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Sound management of late blight, the disease caused by the notorious oomycete pathogen Phytophthora infestans (Mont.) de Bary, is dependent on the pathogen’s population biology. However, for P. infestans population structure to give guidance for disease management, successful information flow between the researchers and the practitioners is paramount. We analysed the population in eastern-Africa to determine the pathogen genotypes present in the region. We characterized the isolates using microsatellite markers and mitochondrial DNA haplotypes to enable comparisons with global populations. A European lineage, 2_A1 was found to be dominating the population in eastern-Africa. In addition, the 2_A1 lineage was found to be more aggressive in terms of lesion size, latent periods and incubation periods when compared to the old US-1 lineage. We thus concluded that the tested aggressiveness traits could have partly contributed to the quick displacement of US-1 by 2_A1 in the region. In a study predicting host durability of a genetically engineered potato with a stack of three resistance genes as well as a conventionally bred potato with a stack of five resistance genes, the assessment of pathogen effector genes proved valuable to deduce which of the R-genes were functional in the field. From the effector study, it can be concluded that effector genes in target local P. infestans populations should inform selection of breeding materials since globally, pathogen populations are very diverse. An assessment of commonly grown potato cultivars in eastern-Africa to quantify their susceptibility to late blight in the field found out that nearly all cultivars had partial resistance to P. infestans. The growers’ choice of cultivars is to high degree governed by market demands. Unfortunately, many cultivars with good resistance to late blight have other undesirable agronomic traits hence the rationale behind growing cultivars that are highly susceptible to late blight. Disease management practices, host durability prediction tools and potato breeding approaches should be suitably adjusted to the existing pathogen population.

Authors/Creators:Njoroge, Anne
Title:Population structure and pathogenicity evolution of Phytophthora infestans affects epidemiology and management of late blight disease
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2019
Number of Pages:66
INjoroge, A.W., Andersson, B., Lees, A., Mutai, C., Forbes, G.A., Yuen, J.E. & Pelle, R. (2018). Genotyping of Phytophthora infestans in eastern-Africa reveals a dominating invasive European lineage. Phytopathology. doi.org/10.1094/PHYTO-O7-18-0234-R
IINjoroge, A.W., Andersson, B.,Yuen, J.E. & Forbes, G.A (2018). Greater aggressiveness in the 2_A1 lineage of Phytophthora infestans may partially explain its rapid displacement of the US-1 lineage in east Africa. Plant Pathology. doi: 10.1111/ppa.1297
IIINjoroge, A.W., Ghislain, M., Andersson, B., Magembe, E., Mutai, C., Pelle, R., Yuen, J.E. & Forbes, G.A. (2018). Predicting durability of host resistance to late blight disease via effector screening in eastern-Africa Phytophthora infestans population. (Submitted).
IVNjoroge, A.W., Andersson, B., Yuen, J.E. & Forbes, G.A. (2018). Quantifying levels of late blight susceptibility in some potato cultivars found in east Africa. (Manuscript).
Place of Publication:Uppsala
Publisher:Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-7760-346-7
ISBN for electronic version:978-91-7760-347-4
Publication Type:Doctoral thesis
Article category:Other scientific
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 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Genetics (medical genetics to be 30107 and agricultural genetics to be 40402)
(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 404 Agricultural Biotechnology > Genetics and Breeding
Keywords:late blight, SSR-genotyping, gene pyramiding, effectors, host resistance
Permanent URL:
ID Code:15976
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
Department:(NL, NJ) > Dept. of Forest Mycology and Plant Pathology
(S) > Dept. of Forest Mycology and Plant Pathology
Deposited By: SLUpub Connector
Deposited On:08 Mar 2019 14:08
Metadata Last Modified:13 Mar 2019 10:29

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