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Identification of Ophiosphaerella herpotricha by Cloned DNA Probes. K. M. Sauer,Graduate research assistant, Department of Plant Pathology, Throckmorton Hall, Kansas State University, Manhattan 66506-5502; S. H. Hulbert, and N. A. Tisserat. assistant professor, and associate professor, respectively, Department of Plant Pathology, Throckmorton Hall, Kansas State University, Manhattan 66506-5502. Phytopathology 83:97-102. Accepted for publication 21 September 1992. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/Phyto-83-97.

DNA of Ophiosphaerella herpotricha, a cause of spring dead spot of bermudagrass, was digested with XbaI and was cloned. A 1.5-kb clone (pOH29) was selected from a genomic library for its specificity and strong hybridization to the total DNA of 29 O. herpotricha isolates. pOH29 did not hybridize to other fungi commonly associated with roots and stolons of bermudagrass, including Leptosphaeria korrae, L. narmari, Gaeumannomyces graminis var. graminis, and G. incrustans. The probe detected O. herpotricha DNA isolated from 200 mg (wet weight) of infected bermudagrass roots and from 1 μ g of lyophilized mycelium. DNA hybridization techniques, with pOH29 as a probe, provide methods of identifying nonsporulating cultures of O. herpotricha and of detecting the pathogen in root tissue. Oligonucleotide primers, developed from pOH29 and pOH20, amplified numerous DNA fragments, ranging in size from 0.2 to 6 kb of total DNA from O. herpotricha as well as several other ectotrophic fungi. Even though no primer pairs that amplified only O. herpotricha DNA were identified, pOH29 may be useful in studying geographic variation among O. herpotricha isolates.