An Attempt to Conduct Association Mapping for Microspore Culture Response in European Wheat Varieties (Triticum aestivum L.)

This project was conducted in close cooperation between the plant breeding company Nordic Seed A/S and Department of Molecular Biology and Genetics, Aarhus University.

The aim was to find molecular markers associated with microspore culture response in wheat. Diversity Array Technology (DArT) was used to genotype a population consisting of 94 bread wheat (Triticum aestivum L.)varieties of European origin.

The genotyping was used to conduct a population structure and linkage disequilibrium analysis, which can support the selection of breeding parents. Bayesian clustering structure and principal component (PCA) analysis was performed using 1,849 polymorphic of 7,000 tested markers, and two major subgroups were identified. The separation correlated with the geographical origin of the varieties, so varieties from Southern and Eastern Europe were separated from modern varieties from Western and Northern Europe. The LD analysis reflected low effective recombination frequency resulting from selective breeding in Europe, since LD decay was found to 23 cM. Diversity of the different chromosomes was reflected by the r²-values being 0.079, 0.060 and 0.229 for the A, B and D genome, respectively. Thus, the D genome is the most conserved, and the A and B genomes showed more polymorphism.

The microspore culture response of the 94 varieties was quantified using a protocol developed at Nordic Seed. An LD mapping of embryo, albino- and green plantlet regeneration showed significant association with DArT markers (LOD score above 2.70). Thus, QTLs found for the mentioned traits for tissue culture response were identified at 14 different wheat chromosomes.