Androgenesis from Festuca pratensis x Lolium multiflorum amphidiploid cultivars in order to select and stabilize rare gene combinations for grass breeding

Androgenesis using amphidiploid cultivars of Festuca platensis x Lolium mul tiflorum as parents, overcame earlier problems that gave rise to widespread plant sterility amongst androgenic Festulolium populations. Two Festuca pr atensis x Lolium multiflorum (2n = 4x = 28) cultivars, Sulino and Felopa, w ere highly amenable to androgenesis and 10% of plants, including some novel androgenic genotypes, had sufficient fertility to produce progeny and furt her generations. The genomes of amphidiploid cultivars, which represent the Fg generation, were the result of considerable intergeneric chromosome rec ombination. Moreover, during cultivar development, natural and breeders' se lection pressures had led to the assembly of gene combinations that conferr ed good growth characters and fertility with the removal of putative delete rious gene combinations. Over 80% of the androgenic plants derived from the amphidiploid F. pratensis x L. multiflorum (2n =4x = 28) had 14 chromosome s and were likely to be dihaploids with a single genome of Lolium and of Fe stuca. In contrast, hybrids of F. pratensis x L. multiflorum (2n=2x=14) fou nd naturally are invariably sterile. Structural reorganization within the g enomes of the androgenic Festulolium 12 plants had restored fertility in ge notypes expected to contain the haploid genome of Lolium and Festuca. This provided opportunities for their future incorporation in breeding programme s and the development of fertile diploid Lolium-Festuca hybrids. Amongst th e androgenic plants, Festulolium genotypes were recovered that conferred ex cellent drought resistance or freezing tolerance and were thought to be hig hly suitable for entry into plant breeding programmes.