Meiotic analysis of induced mutations inOphiostoma ulmi

摘要

Laboratory strains ofOphiostoma ulmicarrying nuclear mutations induced by exposure toN-methyl-Nprime;-nitro-N-nitrosoguanidine were crossed, and the segregation of genetic markers was analyzed in random ascospore progeny. Investigation of 13 auxotrophic mutations and 1 benomyl-resistant mutation provided evidence for at least three linkage groups inO.ulmi. Five loci, identified by mutant allelesade1-1,BENIR-1,cyi1-1,lys3-1, andnic1-1, were assigned to linkage group I, whereas markersade2-1 andlys2-2 were mapped on linkage group II. An additional locus,Met1, was assigned to a third linkage group since mutant alleles at this locus segregated independently from markers on group I or II. TheBen1Rlocus, controlling resistance to benomyl, segregated independently from the mating type locus and thus appeared to differ from theTollocus described by other workers.Key words:Ophiostoma ulmi, Dutch elm disease, mutations, linkage analysis.