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Genomic in situ hybridization (GISH) was used to characterize the chromosome constitutions of individual plants from a set of tetraploid and hexaploid cultivars of Festulolium developed and released in the Czech Republic from hybrids of Lolium multiflorum with Festuca pratensis and F. arundinacea. A simplified GISH protocol readily discriminated parental genomes in the hybrids and facilitated the screening of large numbers of plants per accession. The contribution of parental genomes in the cultivars tested ranged from predominance of chromatin from one of the parents to a more balanced contribution from both parents. However, in none of the cultivars were equal proportions of chromatin from both parents present. The parental contribution to the hybrids was both in the form of complete chromosomes or as chromosome translocations. In hexaploid cultivars from ( L. multiflorum × F. arundinacea) × F. arundinacea hybrids the average numbers of complete L. multiflorum chromosomes ranged from 4.95 to 7.5 and the numbers of translocations from 6.33 to 10.21. Two tetraploid cultivars from ( L. multiflorum × F. arundinacea) × L. multiflorum hybrids showed a strong prevalence of L. multiflorum chromatin and intergeneric translocations were rare. In the tetraploid cultivar ‘Perun’ of the L. multiflorum × F. pratensis hybrid there were 11.7 chromosomes of L. multiflorum and 14.7 recombined chromosomes on average. Reasons for the domination of one of the parental genomes in hybrid cultivars are not clear and are only partially explained by breeding history. Recombination rates of individual genomes in hybrids involving F. arundinacea were evaluated in double hybridization experiments. The results indicated a strong affinity of the L. multiflorum genome for the F. pratensis genome present in F. arundinacea and little affinity for the F. glaucescens genome. This suggests that introgressions from F. arundinacea into L. multiflorum are primarily limited to the F. pratensis genome which can be more readily accessed in L. multiflorum × F. pratensis hybrids. [ABSTRACT FROM AUTHOR]

Molecular diversity and genetic affinity in the Lolium/ Festuca grass complex have been assessed using simple sequence repeat (SSR) marker technology. The genotypic set was derived from three accessions of perennial ryegrass, two cultivars of Italian ryegrass, two cultivars of meadow fescue, two cultivars of tall fescue and 10 accessions from different intergeneric hybrid ( Festulolium) combinations. The majority of the genomic DNA-derived SSR primer pairs from perennial ryegrass (LPSSR) and Italian ryegrass (LMSSR) produced clear, simple and distinctive amplification products from the majority of the genotypes. The efficiency of cross-specific amplification for LPSSR markers varied from 38% in meadow fescue to 93% in two cultivars of Festulolium and from 57% in meadow fescue to 87% in Italian ryegrass for LMSSR markers. Of 40 amplified markers, 14 (35%) produced species-difference alleles in the relation to cultivars used in the present study. Thirty-five LPSSR locus-derived alleles were found to be specific to Lolium species, four to meadow fescue and six to tall fescue. For LMSSR alleles, eight were specific to Lolium species and five were only associated with Italian ryegrass, and null alleles were detected for meadow fescue in all instances. These species-difference markers could clearly identify different accessions of Festulolium. Cluster analysis separated the individual taxa and showed grouping of intergeneric hybrids based on genomic composition. The data distinguished between the species and reflected the known pedigree of the cultivars and the differences between the species. The dendrogram also distinguished between the Festulolium accessions and clearly demonstrated the relations between Festulolium hybrids and their parent species. [ABSTRACT FROM AUTHOR]

In a back-crossing programme involving Lolium multiflorum (the recurrent parent) and Festuca arundinacea, the diploid L. multiflorum phenotype was rapidly recovered with the inclusion, in some progeny, of a small number of genes from the fescue parent. In field drought trials derivatives of these backcross populations were on average less drought resistant than the L. multiflorum parental populations, but 3 % of individuals were as drought resistant as F. arundinacea. After only one cycle of selection and polycrossing these drought-resistant Lolium-like plants, the mean drought resistance of most progeny lines was significantly improved, in some cases to near that of F. arundinacea. Available evidence strongly indicates that this improved drought resistance was due to the transfer of genetic material from Festuca into Lolium. These populations will contribute to variety improvement and to our understanding of the genetics and physiology of drought resistance. [ABSTRACT FROM AUTHOR]