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Applied and Environmental Microbiology, December 1999, p. 5421-5426, Vol. 65, No. 12
Department of Plant Pathology, The Ohio State
University, Ohio Agricultural Research and Development Center, Wooster,
Ohio 44691
Received 1 July 1999/Accepted 21 September 1999
Randomly amplified polymorphic DNA (RAPD) analysis and the PCR
assay were used in combination with dilution plating on a semiselective medium to detect and enumerate propagules of Trichoderma
hamatum 382, a biocontrol agent utilized in compost-amended
mixes. Distinct and reproducible fingerprints were obtained upon
amplification of purified genomic DNA of T. hamatum 382 with the random primers OPE-16, OPH-19, and OPH-20. Three amplified DNA
fragments of 0.35 (OPE-160.35), 0.6 (OPH-190.6), and 0.65 (OPH-200.65) kb were
diagnostic for T. hamatum 382, clearly distinguishing it
from 53 isolates of four other Trichoderma spp. tested.
Some isolates of T. hamatum shared these
low-molecular-weight fragments with T. hamatum 382. However, RAPD analysis of isolates of T. hamatum with all
three random primers used in consecutive PCR tests distinguished
T. hamatum 382 from other isolates of T. hamatum. These three RAPD amplicons were cloned and sequenced,
and pairs of oligonucleotide primers for each cloned fragment were
designed. Use of the primers in the PCR assay resulted in the
amplification of DNA fragments of the same size as the cloned RAPD
fragments from genomic DNA of T. hamatum 382. A combination
of dilution plating on a semiselective medium for
Trichoderma spp. and PCR, with the RAPD primers OPH-19, OPE-16, and OPH-20 or the three sequence-characterized primers, was
used successfully to verify the presence of T. hamatum 382 propagules in nine different soil, compost, and potting mix samples. All 23 Trichoderma isolates recovered on semiselective
medium from commercial potting mixes fortified with T. hamatum 382 were identified as T. hamatum 382, whereas 274 Trichoderma isolates recovered from the other
nine samples were negative in the PCR assay. Thus, this highly specific
combination of techniques allowed detection and enumeration of
propagules of T. hamatum 382 in fortified compost-amended
potting mixes. Sequence-characterized amplified region markers also
facilitated the development of a very simple procedure to amplify DNA
of T. hamatum 382 directly from fortified compost-amended
potting mixes.
0099-2240/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Precise Detection and Tracing of Trichoderma
hamatum 382 in Compost-Amended Potting Mixes by Using
Molecular Markers

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Corresponding author. Mailing address: Department of
Plant Pathology, The Ohio State University/OARDC, 1680 Madison Ave., Wooster, OH 44691. Phone: (330) 263-3678. Fax: (330) 263-3841. E-mail:
miller.769{at}osu.edu.
Present address: Agriculture and Agri-Food Canada, SCPFRC, London,
Ontario, N5V 4T3 Canada.
Present address: Department of Biological Engineering, Yosu
National University, San 96-1, Doonduck-dong, Yosu, CheonNam 550-250, Korea.
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