GENOMIC STRUCTURE OF ANDROGENIC PROGENY OF PENTAPLOID HYBRIDS, FESTUCA-ARUNDINACEA X LOLIUM-MULTIFLORUM

To assess the usefulness of the doubled haploid (DH) method in the bre eding of forage grasses, a sample of anther-derived progeny of pentapl oid F-1 hybrids of Festuca al arundinacea x Lolium multiflorum was kar yotyped using genomic in situ hybridization (GISH). The technique allo wed scoring of the total number of chromosomes, the number of chromoso mes contributed by each parent, and the number and positions of the Fe stuca-Lolium translocation breakpoints. Among 27 plants analysed, 13 b elonged to three clones, effectively reducing the number of different progeny karyotyped to 17. These included 10 haploids, ave doubled hapl oids and two plants for which the origins could not be explained. In a ll plants analysed, a mixture of chromosomes of both parents was prese nt, including an average of 1.88 intergeneric translocations per plant . The translocation breakpoints were distributed along almost the enti re length of the chromosome arms. Chromosome variation among androgeni c progeny appeared much wider than that in the conventional backcross but low vigour and high mortality suggest that this additional Variati on may be difficult to exploit directly in breeding. However, a change in the pattern of recombination makes the entire genome accessible to manipulation.