DIFFERENTIATION AND QUANTIFICATION OF THE CEREAL EYESPOT FUNGI TAPESIA-YALLUNDAE AND TAPESIA-ACUFORMIS USING A PCR ASSAY

Isolates of Tapesia yallundae and Tapesia acuformis were subjected to Random Amplified Polymorphic DNA (RAPD) assay. Amplification products common to isolates of either species were cloned and primers were gene rated from each sequence for use in conventional PCR. The primer pair derived from a T. yallundae specific RAPD marker amplified a product o nly from DNA of T. yallundae isolates and not from DNA of a range of o ther fungal species associated with the stem base disease complex of c ereals. Similarly, the primer pair generated from a T. acuformis-speci fic RAPD marker amplified a product only from DNA of T. acuformis isol ates. Quantitative assays were developed for both species of Tapesia f rom these primer pairs, using competitive PCR Competitive PCR was used to determine the level of colonization of seedlings by each species i n glasshouse- and field-inoculated cereal hosts and results compared t o those for conventional seedling disease assessment.