Species-specific PCR assays for the fungal pathogens Fusarium moniliforme and Fusarium subglutinans and their application to diagnose maize ear rot disease

Fusarium moniliforme Sheldon (syn. F. verticillioides (Sacc.) Nirenberg) an d F. subglutinans (Wollenweber & Reinking) Nelson. Toussoun Bi Marasas comb , nov., two anamorphs of the so-called 'Gibberella fujikuroi species comple x', are important maize pathogens. Together with F. proliferatum. F. culmor um, and F. graminearum (teleomorph: Gibberella zeae) they are involved in t he stalk rot and eat rot disease of maize. All species produce secondary me tabolites (mycotoxins) which are a potential health hazard for humans and a nimals that consume maize and maize products frequently. In this study the development of polymerase chain reaction (PCR) assays for an easy and sensi tive identification of G. fujikuroi anamorphs in maize kernels are describe d. The primer pairs are based on sequences of randomly amplified polymorphi c DNA (RAPD) fragments and are specific for F. moniliforme and F. subglutin ans, respectively. The PCR assays are independent of the high phenotypic va riability of traits which may complicate classification by morphological ch aracters. They detect approximately 100 to 200 fungal genomes in the presen ce of an excess of maize DNA. For the analysis of infected maize kernels a rapid and easy DNA extraction was used which does not introduce inhibitory substances into the PCR. Hence, the assays enable an early identification a nd detection of the two pathogens in host tissue by plant breeders and plan t health inspection services. The assays were successfully applied to ident ify field isolates from Poland and to detect the pathogens in maize ears of various hybrids in Germany.