INTERSPECIFIC GENOMIC REARRANGEMENTS IN ANDROGENIC PLANTS DERIVED FROM A LOLIUM-MULTIFLORUM X FESTUCA-ARUNDINACEA (2N=5X=35) HYBRID

Pollen microspores from a hybrid between Lolium multiflorum (2n = 4x = 28) and Festuca arundinacea (2n = 6x = 42) were cultured and over 200 androgenic green plants established. In the initial hybrid one chromo some from each of the five homoeologous groups was labelled by a disti nct PGI/2 homoeoallele. Segregation of PGI/2 alleles in the male gamet es and in the androgenic plants indicated chromosome pairing preferenc es in the hybrid at meiosis. The pentaploid Festulolium hybrid genome comprised two homologous sets of Lolium (Lm) chromosomes and the polyh aploid set of F. arundinacea, namely one genome of F. pratensis (Fp) a nd two of F. glaucescens (Fg and Fg(1)). There was a high degree of pr eferential chromosome pairing between the two homologous sets of L. mu ltiflorum chromosomes, and each androgenic plant contained a Lolium PG I/2 allele. Results supported earlier work indicating that gamete viab ility depended on the presence of a complete Lolium genome. Genomic in situ hybridization (GISH) was carried out on mitotic chromosome prepa rations of two androgenic plants using the total genomic DNA of L. mul tiflorum as a probe. Recombinants were observed between chromosomes of all three genomes in the pentaploid hybrid, demonstrating the efficac y of the hybrid as a starting point in introgression breeding programm es.