Genetic dissection of marbling trait through integration of mapping and expression profiling.

Marbling traits, defined by the amount of intramuscular fat, has a heritable component and are quantitative in nature, being influenced by many genes of variable individual effects. The identification of the genetic variation associated with marbling is an important step toward the improvement of beef quality through breeding programs and the understanding of the biological network of marbling. A lot of genomic studies based on functional candidate gene approach and quantitative trait locus (QTL) mapping and many transcriptome studies based on expression profiling, respectively, provide information on variation in genomic regions and individual genes associated with marbling and of genes with marbling-associated expression changes. Further, the integrative approach combining mapping and expression profiling data is proving useful for identifying the causal genes for marbling QTLs. Application of this integrative approach to our marbling study using a rat model, Otsuka Long-Evans Tokushima Fatty (OLETF) rat and Japanese Black beef cattle is introduced finally in this review.