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Tracking the fate of biocontrol microorganisms in the environment using intrinsic SCAR markers

Holmberg, Anna-Ida Johnsson (2011). Tracking the fate of biocontrol microorganisms in the environment using intrinsic SCAR markers. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2011:30
ISBN 978-91-576-7565-1
[Doctoral thesis]

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Biocontrol microorganisms can be used as an alternative to conventional chemical pesticides to control plant diseases. This thesis investigated the fate and behaviour of three microbial model control agents with effect against fungal pathogens in cropping systems, and the spread of one of the model strains in bioaerosols. The bacterium Pseudomonas brassicacearum MA250 was monitored in winter wheat systems, in a climate chamber trial and in field conditions. The contribution of strain MA250 to the total microbial load in bioaerosols was also investigated. Two filamentous fungi, Hypocrea parapilulifera IMI206039 and Trichoderma atroviride IMI206040, were investigated on a golf green and in microcosms with soil sampled from the green and with agricultural soil. To track and enumerate the applied strains, intrinsic strain-specific sequence-characterised amplified region (SCAR)
markers were utilised in quantitative real-time PCR. Supplementary methods, such as cultivation-based methods and analysis of the Gram-negative bacterial cell constituent endotoxin, were also included.

In both winter wheat studies, MA250 colonised the roots of healthy seedlings.
Withered seedlings that had died due to snow mould infection were not colonised, indicating the importance of a healthy seedling for proliferation of MA250. In the microcosm studies, with the two fungal biocontrol strains, populations of introduced cells behaved differently depending on the soil. On the golf green, the two fungal biocontrol strains were detected only sporadically, but nevertheless maintained their control effect. In the bioaerosol study, the SCAR marker consistently enabled detection of strain MA250, whereas other methods tested did not. The results showed that MA250 significantly contributed to the total microbial load in aerosols after 60 minutes of coating, when MA250 was added to the system.
However, after 240 minutes of coating this significant increase was not seen and MA250 could only be detected against the background with use of the SCAR marker.

In conclusion, the use of strain-specific SCAR markers proved a reliable method in quantifying added populations in soils, plants and aerosols. This type of information is valuable for optimising the use of the biocontrol microorganisms and to determine the risks associated with application of the strains.

Authors/Creators:Holmberg, Anna-Ida Johnsson
Title:Tracking the fate of biocontrol microorganisms in the environment using intrinsic SCAR markers
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :11 April 2011
Number of Pages:61
I.Johnsson Holmberg, A-I., Melin, P., Levenfors, J.P., Sundh, I. (2009). Development and evaluation of SCAR markers for a Pseudomonas brassicacearum strain used in biological control of snow mould. Biological Control 48, 181-187.
II.Johnsson Holmberg, A-I., Melin, P., Levenfors, J.P., Sundh, I. Determining the fate and behaviour of a seed-applied Pseudomonas brassicacearum strain in a winter wheat field trial, by analysis with SCAR markers. (Manuscript).
III.Feng, X.M., Johnsson Holmberg, A-I., Sundh, I., Ricard, T., Melin, P. Specific SCAR markers and multiplex real-time PCR for quantification of two Trichoderma biocontrol strains in environmental samples. (Submitted)
IV.Johnsson Holmberg, A-I., Nilsson, A.I., Melin, P., Hökeberg, M., Madsen, A.M., Sundh, I. Contribution of a biocontrol Pseudomonas strain to the total microbial load in bioaerosols during experimental seed inoculation. (Manuscript).
Place of Publication:Uppsala
Publisher:Dept. of Microbiology, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-576-7565-1
Publication Type:Doctoral thesis
Full Text Status:Public
Subjects:Obsolete subject words > NATURAL SCIENCES > Biology > Organism biology > Microbiology
Agrovoc terms:biological control agents, pseudomonas fluorescens, genetic markers, winter wheat, trichoderma, pathogenic fungi , biological control, pcr
Keywords:SCAR marker, quantitative real-time PCR, Pseudomonas brassicacearum, Trichoderma/Hypocrea
Permanent URL:
ID Code:8060
Department:(NL, NJ) > Dept. of Microbiology (until 161231)
External funders:Stiftelsen Lantbruksforskning and Swedish Foundation for Strategic Research and ["funders_typename_SLU.id.fund-slu" not defined]
Deposited By: Anna-Ida Johnsson Holmberg
Deposited On:15 Apr 2011 10:43
Metadata Last Modified:02 Dec 2014 10:45

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