Pedigree based analyses: a powerful approach for QTL discovery in pedigreed breeding germplasm and support on breeding decisions

Pedigree Based Analysis (PBA) is an innovative and powerful approach for the discovery and characterisation of marker-trait associations for use in marker assisted breeding. The power of PBA comes from the simultaneous analysis of multiple segregating full sib families, the use of breeding germplasm, and the use of known genetic relationships. The use of multiple families allows representation of wide genetic diversity thus increasing probability that desired genes/alleles are presented and segregating. This also allows examination of QTL performance across different genetic backgrounds, thus providing knowledge on the general applicability of results. Finally, the use of multiple families increases the population size and thereby the statistical power. The use of breeding germplasm of ongoing breeding activities makes results directly applicable and relevant to the breeder and also reduces experimental costs since plant materials and part of the phenotypic measurements are already available. Finally, PBA provides a framework for extending the population and phenotypic data in time, thereby further strengthening statistical power. The statistical approaches and software have been validated through an integrated study on 27 families from five breeding programs from four countries [1] from which some results are presented in figures 1 &2. Current PBA software includes FlexQTLTM for QTL discovery and characterization [1], Pedimap for the graphical presentation [2], Visual-FQ, which provides structured guidance through the analyses and FQ-haplotyper which assigns alleles to haploblocks (sets of tightly linked SNP markers).