OBJECTIVE: To assess the genetic diversity of this fungus through the use of the molecular biology techniques.
PERSONNEL: H.C. Wetzel and N.A. Tisserat
INTRODUCTION:
Spring dead spot (SDS) of bermudagrass is caused by the fungus Ophiosphaerella herpotricha. Classical microbiological methods have failed to reveal the reproductive biology of this organism. This study is using molecular biology techniques to determine whether or not populations of this fungus are clonal (i.e., identical) or variable on a spatial scale such as from fairway to fairway on the same golf course or from golf course to golf course within a region.
MATERIALS AND METHODS:
Numerous turfgrass samples were collected from three golf courses: Independence G.C. in Southeast Kansas and South Lakes G.C. and Shangri-La G.C. in Northeast Oklahoma. Bermudagrass roots exhibiting the presence of darkly pigmented ectotrophic runner hyphae were washed, surface sterilized, and plated on a selective medium. Cultures exhibiting O. herpotricha colony morphology then were transferred to liquid media in preparation for the isolation of the genetic information (DNA) from the isolate. The DNA then was extracted, and isolate identity was confirmed with specific polymerase chain reaction (PCR) primers for O. herpotricha and O. korrae. Ophiosphaerella korrae is the primary agent of SDS in the eastern United States, and we are also interested in documenting whether it occurs with O. herpotricha. Once isolates are identified through PCR, an additional set of PCR primers developed from a DNA library of O. herpotricha, then will be implemented to assess the similarities and differences among the O. herpotricha isolates.
RESULTS:
Isolates from South Lakes G.C. and Shangri-La G.C. have been processed thus far. All isolates from South Lakes G.C. appear to be O. herpotricha. The majority of the isolates from Shangri-La G.C. are O. herpotricha; however, five isolates of O. korrae and one isolate of Leptosphaeria narmari have been recovered from this course. Leptosphaeria narmari is reported as the primary agent of SDS in Australia. Our finding is the first report of this species in North America. We plan on intensively resampling Shangri-La G.C. this spring to see if we can detect any shifts in the populations from one species to another.
Currently, data are being assessed for genetic diversity among the Shangri-La G.C. isolates.