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Abstract Detail

Host/Plant Pathogen Interactions and Plant Health Management

Wijekoon, Champa [1], Pageni, Binod [2], Kawchuk, Lawrence [3].

Rapid molecular characterization of the late blight pathogen Phytophthora infestans.

Phytophthora infestans (Mont.) de Bary continues to jeopardize potato and tomato yield and quality in Canada and worldwide. Genetically diverse and aggressive P. infestans genotypes emerged in Canada and the USA during the 1990s. Genotypes such as US-8, US-11, US-22, US-23, and US-24 were reported recently in USA and Canada with unique epidemiological characteristics. There is an increasing interest in molecular analysis of P. infestans genotypes although phenotypic traits have been described for distinguishing them using mating type, mefenoxam sensitivity, pathogenicity and host preference. Genotypic variations are often characterized based on allozyme banding patterns at the glucose 6-phosphate isomerase (Gpi) locus, mitochondrial DNA haplotype (mtDNA) and the restriction fragment length polymorphism (RFLP) analysis using the multilocus RG57 sequence. Microsatellite analysis was recently introduced using polymorphic markers specific to these clonal variants. We performed microsatellite analysis to distinguish the pathogen isolates collected from various regions of Canada. Alleles at eight selected microsatellite loci successfully differentiated the most dominant five clonal lineages. A majority of the tested isolates were identified as US-8 or US-23 based on their microsatellite profiles. Simultaneously, a new terminal restriction fragment length polymorphism (T-RFLP) method was validated using RG57, a genetic marker of P. infestans. T-RFLP is a rapid semiquantitative fingerprinting method extensively used for comparative analysis of microbial communities. In this method, fluorescent end-labelled polymerase chain reaction (PCR)-amplified markers were digested with one restriction endonuclease enzyme, resulting in the production of fluorescent labelled terminal restriction fragments (TRFs) of different lengths. The five dominant US genotypes (US-8, US-11, US-22, US-23 and US-24) were successfully distinguished at the molecular level by T-RFLP analysis. Application of T-RFLPs will provide the robust genotyping of P. infestans obtained with RG57 RFLP analysis but requires substantially less amount of pathogen.

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1 - Agri-Food Canada (AAFC), Science and Technology, 5403 1 Avenue South, Lethbidge, AB, T1J 4B1, Canada
2 - University of Lethbridge, Biochemistry, 4401 University Drive, Lethbidge, AB, T1K 3M4, Canada
3 - Agri-Food Canada (AAFC), 5403 1 Avenue South, Lethbidge, AB, T1J 4B1, Canada

Phytophthora infestans.

Presentation Type: Oral Paper:Papers for Topics
Session: 55
Location: Salon 2/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 4:00 PM
Number: 55004
Abstract ID:825
Candidate for Awards:None

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