A simplified QTL mapping approach for screening and mapping of novel AFLP markers associated with beef marbling.

Genome screening of quantitative trait loci (QTL) for a complex trait is usually costly and highly laborious, as it requires a large number of markers spanning the whole genome. Here we present a simplified approach for screening and mapping of QTL-linked markers for beef marbling using a WagyuxLimousin F(2) reference population. This simplified approach involves integration of the amplified fragment length polymorphism (AFLP) with DNA pooling and selective genotyping and comparative bioinformatics tools. AFLP analysis on two high and two low marbling DNA pools yielded ten visually different markers. Among them, four were confirmed based on individual AFLP validation. Sequencing and in silico characterization assigned two of these AFLP markers to bovine chromosomes 1 (BTA1) and 13 (BTA13), which are orthologous to human chromosomes HSA21q22.2 and HSA10p11.23 with both regions harboring QTL for obesity-related phenotypes. Both AFLP markers showed significantly large additive genetic effects (0.28+/-0.11 on BTA1 and 0.54+/-0.21 on BTA13) on beef-marbling score (BMS) (P<0.05). Overall, this approach is less time consuming, inexpensive and in particular, suitable for screening and mapping QTL-linked markers when targeting one or a few complex traits.