Genetic analysis of Lolium.: I.: Identification of linkage groups and the establishment of a genetic map

A genetic map of Lolium has been produced using isozyme, restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD) markers applied to a segregating family derived from an F-1 hybrid plant of L. perenne x L. multifolorum provenance, crossed on to a doubled haploid L. perenne. A total of 106 markers, out of a total of 160 polymorphic loci analysed, have been ascribed to seven linkage groups covering a map distance of 692 cM. Two of these groups may be allocated to chromosomes 2 and 6 of the Lolium genome. The remaining unallocated markers, the majority of which showed severe segregation distortion, could be associated into small groups of two or three markers which showed no linkage with the main groups at a LOD of 2.8 or, if associated, could not be mapped in a satisfactory manner. This high incidence of disturbed segregations could be accounted for by the use of an interspecific hybrid between two species of differing genome size, with consequent cytological imbalance.