Cloning and mapping of the Brassica napus orthologs of the AtPirin gene associated with seed germination and seedling vigour, and generation of molecular markers to break the linkage with yellow seed colour in oilseed rape

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Yellow coloured seeds are of particular interest for oilseed rape (Brassica napus) breeding because of their association with a thinner seed coat resulting in reduced dietary fibre content. This considerably improves the feed and protein quality of rapeseed meal after oil extraction. However, the yellow-seeded phenotype is also associated with negative agronomic characters including a reduced germination rate and inhibition of seedling development and vigour. However, genetic variation exists with regard to the degree of association in rapeseed. In Arabidopsis, the gene AtPirin1 has an analogous effect on seed germination and early seedling development, and a B. napus homolog of this gene (BnPirin) has been found to be strongly over-expressed in yellow-seeded oilseed rape. Based on the hypothesis that BnPirin is closely linked to the major partially dominant gene for yellow seed colour in B. napus, the aim of this project is to identify and map all orthologs of the AtPirin gene in B. napus and study their expression in different yellow-seeded rapeseed lines. By comparing the BnPirin map locations with QTL for germination rate, seedling development, vigour and relevant plant growth hormones (particularly abscisic acid and ethylene), the intention is to develop molecular markers for transcriptionally active copies of the gene that can be used for a marker-assisted selection (MAS) of yellow-seeded rapeseed lines with no linkage drag for germination rate and seedling development (vigour).