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Conference abstract2008

Quantitative PCR detection for mapping in-field variation of Plasmodiophora and Aphanomyces euteiches

Almquist, Charlotta; Wallenhammar, Ann-Charlotte; Jonsson, Anders


Spatial variability within fields and variations between fields in the occurrence of Plasmodiophora brassicae and of Aphanomyces euteiches were determined on farms in south and central Sweden using quantitative PCR-assays. The molecular methods are validated by traditional bioassay techniques. Soil has been sampled using GPS from fields where the disease occurred and the results presented as an interpolated disease map. Relations between the occurrence of pathogens and soil parameters such as pH, soil type, clay content, plant available macro- and micro nutrients are evaluated. Species-specific primers and TaqMan fluorogenic probes were designed to amplify small regions of P. brassicae and A. euteiches ribosomal DNA. Total genomic DNA was extracted and purified from soil samples using commercial kits. The amount of pathogen DNA was quantified using a standard curve generated by including reactions containing different amounts of a plasmid carrying the P. brassicae or A. euteiches target sequence. Regression analysis showed that the assays were linear over at least 6-7 orders of magnitude (R2>0.99) and that the amplification efficiency was >95%.A considerable (100-1000 times) variation in DNA–content was observed in the sampled fields for P. brassicae, less for A. euteiches. Molecular methods for routine diagnosis will enable producers to respond to market opportunities. The results will constitute basic data for an evaluation of the benefit of a systematic detection of soil borne pathogens by a quantitative PCR-method aiming at an efficient application in Precision Agriculture

Published in

Title: Journal of Plant Pathology


ICPP 2008, 9th International Congress of Plant Pathology