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A genetic map of Lolium has been produced using isozyme, restriction fragment length polymorphism (RFLP) and random amplified poiymorphic DNA (RAPD) markers applied to a segregating family derived from an F[sub1] hybrid plant of L. perenne × L. multiflorum 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 Loliurn 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 24.8 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. [ABSTRACT FROM AUTHOR]

A series of lines, differing in isozyme genotype, were constructed by selection, from within three cultivars of Lolium perenne. Field assessment of the progeny of these selected lines revealed variation in yield and timing of inflorescence emergence. This variation between lines from within a cultivar could not: be accounted for by the differing levels of homozygosity attained. In some instances differences in yield were associated with homozygosity for specific alleles at the PGI/2 locus, background genotype was however, of major importance. The variation identified could be attributable to founder effects or possible linkage of quantitative trait loci PGI/2 locus. [ABSTRACT FROM AUTHOR]