This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Mauchline, T. H. Articles by Hirsch, P. R. Search for Related Content PubMed PubMed Citation Articles by Mauchline, T. H. Articles by Hirsch, P. R. Agricola Articles by Mauchline, T. H. Articles by Hirsch, P. R.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, April 2002, p. 1846-1853, Vol. 68, No. 4
0099-2240/02/$04.00+0     DOI: 10.1128/AEM.68.4.1846-1853.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.

Quantification in Soil and the Rhizosphere of the Nematophagous Fungus Verticillium chlamydosporium by Competitive PCR and Comparison with Selective Plating

IACR-Rothamsted, Harpenden, Hertfordshire AL5 2JQ,¹ Department of Agriculture, The University of Reading, Earley Gate, Reading RG6 6AT, United Kingdom²

Received 6 November 2001/ Accepted 15 January 2002

A competitive PCR (cPCR) assay was developed to quantify the nematophagous fungus Verticillium chlamydosporium in soil. A -irradiated soil was seeded with different numbers of chlamydospores from V. chlamydosporium isolate 10, and samples were obtained at time intervals of up to 8 weeks. Samples were analyzed by cPCR and by plating onto a semiselective medium. The results suggested that saprophytic V. chlamydosporium growth did occur in soil and that the two methods detected different phases of growth. The first stage of growth, DNA replication, was demonstrated by the rapid increase in cPCR estimates, and the presumed carrying capacity (PCC) of the soil was reached after only 1 week of incubation. The second stage, an increase in fungal propagules presumably due to cell division, sporulation, and hyphal fragmentation, was indicated by a less rapid increase in CFU, and 3 weeks was required to reach the PCC. Experiments with field soil revealed that saprophytic fungal growth was limited, presumably due to competition from the indigenous soil microflora, and that the PCR results were less variable than the equivalent plate count results. In addition, the limit of detection of V. chlamydosporium in field soil was lower than that in -irradiated soil, suggesting that there was a background population of the fungus in the field, although the level was below the limit of detection. Tomatoes were infected with the root knot nematode (RKN) or the potato cyst nematode (PCN) along with a PCN-derived isolate of the fungus (V. chlamydosporium isolate Jersey). Increases in fungal growth were observed in the rhizosphere of PCN-infested plants but not in the rhizosphere of RKN-infested plants after 14 weeks using cPCR. In this paper we describe for the first time PCR-based quantification of a fungal biological control agent for nematodes in soil and the rhizosphere, and we provide evidence for nematode host specificity that is highly relevant to the biological control efficacy of this fungus.

This article has been cited by other articles:

• Pujol, M., Badosa, E., Manceau, C., Montesinos, E. (2006). Assessment of the Environmental Fate of the Biological Control Agent of Fire Blight, Pseudomonas fluorescens EPS62e, on Apple by Culture and Real-Time PCR Methods. Appl. Environ. Microbiol. 72: 2421-2427 [Abstract] [Full Text]