Quantitative trait loci for winter hardiness and other agronomic traits in the progeny of two amphiploid Festulolium hybrids (Festuca pratensis * Lolium perenne) backcrossed twice to tetraploid Lolium perenne

To clarify the effects of the introduction of Festuca pratensis-derived genomic regions in a tetraploid Lolium perenne genomic background, we analyzed quantitative trait loci (QTLs) for winter hardiness and eight other agronomic traits using two mapping populations generated by sequential backcrosses of two different amphiploid F. pratensis � L. perenne hybrids to tetraploid L. perenne. We constructed two interspecific linkage maps: FLBC2A (143 DNA markers, 301.2 cM total) and FLBC2C (126 markers, 256.2 cM), based on F. pratensis-derived alleles, with 72 markers in common. Interval mapping detected QTLs for seven traits in FLBC2A and for six traits in FLBC2C. In both populations, QTLs for winter hardiness with a positive effect of the F. pratensis allele were detected around common markers on linkage group (LG) 1. In FLBC2A, other additional QTLs for winter hardiness with a positive effect of the F. pratensis allele were detected on LG4 and LG5, and one with a negative effect was detected on LG2. In both populations, a QTL for heading date was detected on LG7. Quantitative trait loci for vigor after planting and stubble width were detected on different LGs between populations. Quantitative trait loci for dry matter yield before winter, plant growth habit, inflorescence length, number of spikelets per inflorescence, and leaf width were detected in only one population. Population-dependent QTLs thought to be involved in intraspecific variation in addition to interspecific one. On the other hand, QTLs found in the two different populations could lead to the development of versatile markers for Festulolium breeding.