DETECTION OF LEPTOSPHAERIA-KORRAE WITH THE POLYMERASE CHAIN-REACTION AND PRIMERS FROM THE RIBOSOMAL INTERNAL TRANSCRIBED SPACERS

Leptosphaeria korrae, the causal agent of necrotic ring spot, is a des tructive patch disease of Kentucky bluegrass. To develop a rapid molec ular test for the detection of this pathogen, an assay based on the po lymerase chain reaction (PCR) was developed utilizing the internal tra nscribed spacer region 1 (ITS 1) oft. korrae ribosomal DNA. DNA sequen ce comparison showed 94.8% similarity of the ITS 1 region among L. kor rae isolates and only 45-50% similarity between L. korrae and other fu ngal species. Based on ITS 1 sequence differences, a pair of oligonucl eotide primers, LK17S and 5.8SC, were selected. With PCR, the primers specifically amplified L. korrae DNA and did not amplify DNA isolated from 15 other fungal species or healthy Kentucky bluegrass. The assay could also specifically detect L. korrae in diseased turfgrass samples .