True-breeding mapping populations include:
True-breeding or immortal mapping populations maintain homozygous, non-segregating genotype across generations so that same genotype can be phenotyped repeatedly in different environments and years. Examples include doubled haploid lines where chromosome doubling produces instant homozygosity, recombinant inbred lines after F6 selfing, and near-isogenic lines that differ only at introgressed segment. F2, BC1F1, and testcross populations are transient and heterozygous, segregating each generation, unsuitable for replicated phenotyping because genotype changes upon selfing and allele frequencies shift. Doubled haploids are particularly useful because they derive from gametes of F1, capture recombination only in one meiosis but provide fully homozygous lines within one year, ideal for genetic map construction and QTL analysis where additive effects estimated without dominance interference. Their immortal nature facilitates accumulation of multi-year phenotypic data and sharing among breeding programs for meta-analysis and verification of marker-trait associations across laboratories and environments for stability. Comparative mapping across populations using same DH panel allows identification of conserved QTLs and syntenic relationships between species, supporting translational breeding where genes discovered in model crops inform improvement of orphan crops through shared genomic resources and collinearity, accelerating genetic improvement across diverse agricultural systems.
Ref: Paterson AH et al. Mendelian mapping populations; Snape & Parker DH as true-breeding mapping resource 2007