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Background: The breeding value of a crossbred individual can be expressed as the sum of the contributions from each of the contributing pure breeds. In theory, the breeding value should account for segregation between breeds, which results from the difference in the mean contribution of loci between breeds, which in turn is caused by differences in allele frequencies between breeds. However, with multiple generations of crossbreeding, how to account for breed segregation in genomic models that split the breeding value of crossbreds based on breed origin of alleles (BOA) is not known. Furthermore, local breed proportions (LBP) have been modelled based on BOA and is a concept related to breed segregation. The objectives of this study were to explore the theoretical background of the effect of LBP and how it relates to breed segregation and to investigate how to incorporate breed segregation (co)variance in genomic BOA models.
Results: We showed that LBP effects result from the difference in the mean contribution of loci between breeds in an additive genetic model, i.e. breed segregation effects. We found that the (co)variance structure for BS effects in genomic BOA models does not lead to relationship matrices that are positive semi-definite in all cases. However, by setting one breed as a reference breed, a valid (co)variance structure can be constructed by including LBP effects for all other breeds and assuming them to be correlated. We successfully estimated variance components for a genomic BOA model with LBP effects in a simulated example.
Conclusions: Breed segregation effects and LBP effects are two alternative ways to account for the contribution of differences in the mean effects of loci between breeds. When the covariance between LBP effects across breeds is included in the model, a valid (co)variance structure for LBP effects can be constructed by setting one breed as reference breed and fitting an LBP effect for each of the other breeds.
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http://dx.doi.org/10.1186/s12711-023-00810-5 | DOI Listing |
J Dairy Sci
September 2025
Department of Animal and Dairy Sciences, University of Wisconsin, Madison, WI, 53706. Electronic address:
Fertility traits such as daughter pregnancy rate (DPR), cow conception rate, and heifer conception rate are key predictors of reproductive performance in dairy herds. However, their low heritability, likely due to their multifactorial nature and difficulty in measuring phenotypes, poses challenges for genetic improvement. Oocyte competence, encompassing nuclear and cytoplasmic maturation, is a critical factor influencing fertility.
View Article and Find Full Text PDFBMC Plant Biol
September 2025
Rice Science Center, Kasetsart University, Kamphaeng Saen Campus, Nakhon Pathom, 73140, Thailand.
Background: Tiller number is a critical component of rice yield, as it directly influences overall productivity. While upland rice varieties are well adapted to lowland environments and prove resilient to fluctuating water availability, their typically low tillering capacity limits their performance in lowland ecosystems where conditions are more conducive to achieving higher yields.
Results: To facilitate the marker-assisted selection (MAS) breeding of upland rice cultivars suitable for lowland conditions, we performed QTL-seq analysis using populations derived from a cross between a high-tillering lowland indica parent (PTT1) and a low-tillering upland tropical japonica line (NDCMP49).
Nat Plants
September 2025
Laboratory of Genome Biology, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Poznan, Poland.
Meiotic crossovers, which exchange DNA between homologous chromosomes, are vital for accurate segregation and generate genetic diversity. In plant breeding, they help create new haplotypes by combining beneficial alleles. In Arabidopsis, heterozygous regions in an otherwise homozygous background attract more crossovers than in full F hybrids-a phenomenon so far observed only in this self-fertilizing species.
View Article and Find Full Text PDFBreed Sci
April 2025
Western Region Agricultural Research Center, National Agriculture and Food Research Organization (NARO), Fukuyama, Hiroshima 721-8514, Japan.
Strong yellow color, caused by carotenoid accumulation, in semolina flour made from durum wheat ( L. subsp. (Desf.
View Article and Find Full Text PDFBreed Sci
April 2025
Institute of Crop Science, NARO, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8518, Japan.
In barley ( L.), many DNA markers have been developed for the selection of traits related to various end-use purposes of breeding. To perform rapid marker-assisted selection of many lines, we developed Kompetitive Allele-Specific PCR (KASP) markers, which can be used for effective automatic genotyping of single nucleotide polymorphisms (SNPs).
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