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

Abstract

Androgenesis using amphidiploid cultivars of Festuca pratensis × Lolium multiflorum as parents, overcame earlier problems that gave rise to widespread plant sterility amongst androgenic Festulolium populations. Two Festuca pratensis × Lolium multiflorum (2n=4x=28) cultivars, Sulino and Felopa, were highly amenable to androgenesis and 10% of plants, including some novel androgenic genotypes, had sufficient fertility to produce progeny and further generations. The genomes of amphidiploid cultivars, which represent the F8 generation, were the result of considerable intergeneric chromosome recombination. Moreover, during cultivar development, natural and breeders’ selection pressures had led to the assembly of gene combinations that conferred good growth characters and fertility with the removal of putative deleterious gene combinations. Over 80% of the androgenic plants derived from the amphidiploid F. pratensis × L. multiflorum (2n=4x=28) had 14 chromosomes and were likely to be dihaploids with a single genome of Lolium and of Festuca. In contrast, hybrids of F. pratensis × L. multiflorum (2n=2x=14) found naturally are invariably sterile. Structural reorganization within the genomes of the androgenic Festulolium plants had restored fertility in genotypes expected to contain the haploid genome of Lolium and Festuca. This provided opportunities for their future incorporation in breeding programmes and the development of fertile diploid Lolium–Festuca hybrids. Amongst the androgenic plants, Festulolium genotypes were recovered that conferred excellent drought resistance or freezing tolerance and were thought to be highly suitable for entry into plant breeding programmes.

Cytogenetics of Festulolium (<i>Festuca </i>×<i> Lolium</i> hybrids)

“…F. arundinacea hybrids are mostly sterile, which hampers their use in breeding . In contrast, Lesniewska et al (2001) reported partial fertility of haploids produced from tetraploid F. pratensis ! L. multiflorum hybrids.…”

“…Since the first successful in vitro haploid generation from cultured anthers (Nitzsche, 1970), androgenesis has been used frequently for haploid and dihaploid production in Lolium -Festuca complex (i.e. Rose et al, 1987;Zwierzykowski et al, 1998a, 1999b, Zare et al, 1999Lesniewska et al, 2001;Kopecky et al, 2005b).…”

“…L. multiflorum and L. perenne ! F. pratensis hybrids (Lesniewska et al, 2001;Guo et al, 2005). We used androgenesis to reduce the chromosome numbers from tetraploid to diploid for turf breeding of L. perenne !…”

“…Drought resistance was introduced from fescue into ryegrass in several breeding programs (Humphreys and Thomas, 1993;Humphreys and Pašakinskiene, 1996;Lesniewska et al, 2001;Kosmala et al, 2006a). Humphreys and Thomas (1993) introgressed quantitative trait loci (QTLs) for drought tolerance from F. arundinacea to L. multiflorum .…”

A decade of “chromosome painting” in <i>Lolium</i> and <i>Festuca</i>

“…These instabilities can have usefulness providing new speculations on genome evolution, as well as practical implications for obtaining novel genome compositions through androgenesis (Leśniewska et al, 2001).…”