GENE FLOW BETWEEN GEOGRAPHIC POPULATIONS OF MYCOSPHAERELLA-GRAMINICOLA (ANAMORPH SEPTORIA-TRITICI) - DETECTED WITH RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM MARKERS

We used DNA restriction fragment length polymorphism (RFLP) markers to assess the potential for gene flow between geographically separated populations of Mycosphaerella graminicola. We used 13 RFLP loci and DNA fingerprints to compare the genetic structure of Oregon and California populations of M. graminicola separated by 750 km. The two populations shared the majority of frequent alleles at a number of loci. Many alleles were present at similar frequencies. The populations had similar levels of genetic diversity. Genetic and genotypic variation were distributed on a very small scale in both populations. An indirect measure of gene flow based on Wright's island model (Nm) estimated the number of individuals that have migrated between the populations as 12, which is sufficient to prevent the populations from differentiating significantly. Gene flow on this scale could have significant implications for plant breeding programs.