Interspecific genomic rearrangements in androgenic plants derived from a Lolium multiflorum×Festuca arundinacea (2n=5x = 35) hybrid

Abstract

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 chromosome from each of the five homoeologous groups was labelled by a distinct PGI/2 homoeoallele. Segregation of PGI/2 alleles in the male gametes and in the androgenic plants indicated chromosome pairing preferences in the hybrid at meiosis. The pentaploid Festulolium hybrid genome comprised two homologous sets of Lolium (Lm) chromosomes and the polyhaploid set of F. arundinacea, namely one genome of F. pratensis (Fp) and two of F. glaucescens(Fg and Fg1). There was a high degree of preferential chromosome pairing between the two homologous sets of L. multiflorum chromosomes, and each androgenic plant contained a Lolium PGI/2 allele. Results supported earlier work indicating that gamete viability depended on the presence of a complete Lolium genome. Genomic in situ hybridization (GISH) was carried out on mitotic chromosome preparations of two androgenic plants using the total genomic DNA of L. multiflorum as a probe. Recombinants were observed between chromosomes of all three genomes in the pentaploid hybrid, demonstrating the efficacy of the hybrid as a starting point in introgression breeding programmes.