Phytophthora infestans in a single field in southwest Sweden early in spring: symptoms, spatial distribution and genotypic variation

• Published in: Plant pathology Vol. 56; no. 4; pp. 573 - 579
• Main Authors: Widmark, A.‐K., Andersson, B., Cassel‐Lundhagen, A., Sandström, M., Yuen, J. E.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.08.2007; Blackwell
• Subjects: Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; mating type; microsatellite markers; mitochondrial haplotype; oospores; Phytopathology. Animal pests. Plant and forest protection; Phytophthora infestans; potato late blight; soilborne inoculum; Solanum tuberosum; Scandinavia; Sweden; Europe; Genetic variability; Mycosis; Plant pathogen; Molecular marker; microsatellite markers; Spores; Field; Mitochondria; Microsatellite DNA; Spring(season); Phytophthora infestans; soilborne inoculum; Season; Haplotype; Mating type; oospores; Stramenopila; Soilborne transmission; Cell organelle; mitochondrial haplotype; Oomycota; Infection; Symptomatology; Southwest; potato late blight; Spatial distribution; Single; Transmission mode; Inoculum
• ISSN: 0032-0862; 1365-3059
• DOI: 10.1111/j.1365-3059.2007.01618.x

Sixty‐eight isolates of Phytophthora infestans were collected from an early planted, fleece‐protected potato field in southwest Sweden in May 2001. No infection was observed in the neighbouring fields. In the field investigated, infected plants were found in six discrete foci, with symptoms almost exclusively observed in the lower part of the canopy and numerous infections found on stems and on leaves touching the ground. The structure of the population was analysed based on mating type, mitochondrial haplotype and microsatellites (SSRs) as markers. Both mating types were present and haplotypes Ia and IIa were detected. Among 61 isolates analysed with microsatellite markers, 14 multilocus genotypes were distinguished based on six polymorphic loci. Out of the six foci, three included 3–5 genotypes each. There were unique genotypes in all foci, except two closely situated to each other. These findings strongly suggest that soilborne oosporic inoculum contributed significantly to initiate the late‐blight epidemic in the investigated field.