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Research article - Peer-reviewed, 2009

Development and evaluation of SCAR markers for a Pseudomonas brassicacearum strain used in biological control of snow mould

Johnsson, Anna-Ida; Melin, Petter; Levenfors, Jens; Sundh, Ingvar


Biological control microorganisms have long been promoted as an alternative to conventional pesticides. Before registration of a microbial biocontrol product for commercial sale, it must be evaluated as regards potential spread and persistence after release. In this study, strainspecific sequence-characterized amplified region (SCAR) markers were developed to monitor the biocontrol candidate strain Pseudomonas brassicacearum MA250, which is effective against snow mould (Microdochium nivale). One SCAR marker, OPA2-73, was used in quantitative real-time PCR (Q-PCR) on samples from a climate chamber experiment in which winter wheat seeds were treated with the bacterium or a chemical control agent, or left untreated. The results showed that MA250 persisted for up to 3 weeks after sowing on the kernel residues and also colonized the roots of treated seedlings. Total MA250 cell numbers on biocontrol treated seedlings after three weeks were approximately 10(6) Cells, compared with the original inoculum of 10(6)-10(7) cells per seed. Corresponding cell numbers of MA250 on chemically treated and untreated seedlings were below the detection limit. This study shows that SCAR marker OPA2-73 is a specific and sensitive tool for monitoring the biocontrol microorganism MA250 in environmental samples. (C) 2008 Elsevier Inc. All rights reserved.


SCAR; Pseudomonas brassicacearum; Microdochium nivale; Biological control; Monitoring; Real-time PCR

Published in

Biological Control
2009, Volume: 48, number: 2, pages: 181-187