What is QTL mapping?
The acronym QTL refers to Quantitative Trait Locus. A QTL is a chromosomal region suspected to contain a gene (or cluster of genes) that contributes to the variation observed at a quantitative trait. QTLs are detected through QTL mapping experiments. In crop plants, these experiments utilize experimental pedigrees, usually produced from crossing two inbred lines. A commonly used QTL mapping pedigree is the F2 pedigree. The first offspring generation (the F1), resulting from the crossing of the two parental inbred lines, is uniformly heterozygous. However, in the second generation (the F2), formed by intermating among the F1, the parental alleles are segregating and most chromosomes will be recombinant mixtures of the parental chromosomes. Genes and genetic markers that are close together on a chromosome will tend to co-segregate in the F2 (the same allele combinations that occurred in one of the parents will tend to occur together in the offspring). The closer together are two markers
