POLYMERASE CHAIN-REACTION ASSAYS FOR THE DETECTION OF STAGONOSPORA-NODORUM AND SEPTORIA-TRITICI IN WHEAT

Polymerase chain reaction (PCR) primers have been developed that can distinguish important wheat pathogenic fungal species and detect their DNA in infected wheat leaf tissues. Septoria tritici (teleomorph Mycosphaerella graminicola) and Stagonospora nodorum = Septoria nodorum (teleomorph Phaeosphaeria nodorum), are agronomically significant pathogens of wheat, causing wheat leaf and glume blotch, respectively. Primers made to conserved sequences of the ribosomal DNA were used to PCR amplify and clone the internal transcribed spacer (ITS) regions from S. nodorum and S. tritici. The ITS regions were sequenced, the sequences were aligned, and species-specific PCR primers were designed to the polymorphic regions. These ITS-derived primers were used to amplify specific fragments from the fungi from which they were designed, thus allowing the detection of the pathogens. The primers also successfully amplified similar-sized fragments from wheat tissues infected with the respective fungi.