Molecular Mapping of QTLs Associated with Important Forage Traits in Tall Fescue

摘要

Tall fescue (Festuca arundinacea Schreb.) is a major peremiial forage crop in the temperate regions of the world. Genetic linkage maps are an essential tool for genome research and have been used for tagging important traits. Tall fescue- and conserved grass EST-SSRs, genomic SSRs from tall fescue and Festuca x Lolium hybrids, and gene-specific STS markers from tall fescue orthologs were used to construct parental linkage maps followed by bi-parental consensus maps. A two-way pseudo testcross mappingstrategy was followed to construct the linkage groups. The majority of markers segregated from either parent and showed a 1:1 Mendelian segregation ratio, thus indicating that the loci were in a heterozygous state in one parent and in a homozygous recessive state in the other parent. Markers present in both parents and showing a 3:1 segregation ratio were used for identifying homologous groups between maps. A distinctly reduced level of recombination was observed in the male parent compared to the female parent. Markers in general were evenly disfributed throughout the genome. However, clustering of markers in some regions and few gaps of >20 cM in some linkage groups (LGs) were also evident. The mapping population was evaluated in field experiments at Ardmore, OK, for three consecutive years. Data on morphological, reproductive and quality traits were collected. Quantitative trait loci (QTL) and markers associated with these fraits were identified. Marker-assisted breeding was initiated with markers associated with forage digestibility.