eQTL mapping of candidate genes for flower colour as a model for genetical genomics in Azalea

Flower colour in azalea is inherited as a semi-qualitative trait and is mainly determined by differences in anthocyanins and flavonols. A two-gene model is used to explain the phenotypic variation between white, brick red and carmine red colour: W in case the flower petals contain anthocyanins and Q if flavonols are present as co-pigments. However, the regulatory network behind this pathway is still unclear. To identify key driver genes of the molecular pathway involved, a genetical genomics approach was followed. Genetics was combined with gene expression profiling, resulting in eQTL mapping. So far, mainly micro-array data have been used for this, limiting the technique to large scale projects. Nevertheless, qPCR can be a good and cost?efficient alternative, as we will demonstrate for flower colour in azalea. A genetic map of 13 linkage groups was constructed using a crossing population segregating for flower colour (250 plants). Besides anonymous AFLP and SSR markers also a set of functional markers