QTL analyses and comparative genetic mapping of frost tolerance, winter survival and drought tolerance in meadow fescue (Festuca pratensis Huds.)

Quantitative trait loci (QTLs) for frost and drought tolerance, and winter survival in the field, were mapped in meadow fescue (Festuca pratensis Huds.) and compared with corresponding traits in Triticeae and rice to study co-location with putatively orthologous QTLs and known abiotic stress tolerance genes. The genomes of grass species are highly macrosyntenic; however, the Festuca/Lolium and Triticeae homoeologous chromosomes 4 and 5 show major structural differences that is especially interesting in comparative genomics of frost tolerance. The locations of two frost tolerance/winter survival QTLs on Festuca chromosome 5F correspond most likely to the Fr-A1 and Fr-A2 loci on wheat homoeologous group 5A chromosomes. A QTL for long-term drought tolerance on chromosome 3F (syntenic with rice 1) support evidence from introgression of Festuca genome segments onto homoeologous Lolium chromosomes (3L) that this genome region is an excellent source of tolerance towards drought stress. The coincident location of several stress tolerance QTL in Festuca with QTL and genes in Triticeae species, notably dehydrins, CBF transcription factors and vernalisation response genes indicate the action of structural or regulatory genes conserved across evolutionarily distant species.