CONTRASTING COMPLEXITY OF 2 RUST RESISTANCE LOCI IN FLAX

DNA probes from the L6 rust resistance gene of flax (Linum usitatissim um) hybridize to resistance genes at the unlinked M locus, indicating sequence similarities between genes at the two loci, Genetic and molec ular data indicate that the L locus is simple and contains a single ge ne with 13 alleles and that the M locus is complex and contains a tand em array of genes of similar sequence. Thus the evolution of these two related loci has been different. The consequence of the contrasting s tructures of the L and M loci on the evolution of different rust resis tance specificities can now be investigated at the molecular level.