Abstract

Trapping nurseries trialed at two screening sites in Burkina Faso appeared to be an effective tool to characterize the virulence spectrum of blast populations using limited equipment and reduced labor. It made it possible to identify the best site to be used for screening for durable resistance. The effectiveness of some resistance genes indicated that they could be pyramided to provide durable resistance to blast fungus in Burkina Faso. The study also revealed the possible existence of new pathotypes in Burkina Faso. Fifty-five isolates of the blast fungus, Magnaporthe grisea, collected from the nurseries and rice fields were analyzed using random amplified polymorphic DNA (RAPD) PCR. Five major groups (Mg-1, Mg-2, Mg-3 Mg-4 and Mg-5) were defined.Mg-1, Mg-2 and Mg-3 were the largest groups representing, 30.9, 25.5 and 30.9% of the 55 isolates analyzed. Only 9.1 and 3.6% belong to Mg-4 and Mg-5, respectively. Our results confirmed that RAPD PCR offers an inexpensive and speedy means of generating markers for analyzing the population structure of the blast fungus.

Key words: Magnaporthe grisea, Oryza spp., Rice, graminaceous, pathogenicity, virulence spectrum, genetic fingerprinting, RAPD PCR, polymorphism.