Redundancy, Subfunctionalization and Neofunctionalization in the Gene Regulatory Network Underlying Flowering in Brassica napus

Studies of the genes underlying flowering time control in model species have led to the development of computational gene network models to understand how environmental signals are integrated by plants. Such network models, if they existed for the crop Brassica napus, would facilitate directed breeding efforts to optimise crop scheduling. However, despite the close homology between Brassica napus and the model plant Arabidopsis thaliana, existing gene regulatory network models cannot be directly transferred between species. This is due to the ancestral genome triplication and allopolyploidy in the Brassica napus genome which has resulted in multiple copies of flowering time related genes. Whether these additional gene copies share similar positions and functions in the gene regulatory network as their Arabidopsis thaliana counterparts remains to be determined.

To address these questions gene expression was measured in leaf and apex tissue of spring and winter varieties of Brassica napus across development, including the floral transition. Through the use of self-organizing maps and correlation networks, the expression dynamics of genes were investigated to identify potential gene redundancy, subfunctionalization and neofunctionalization. These findings are discussed in relation to sequence polymorphisms to build a more complete picture of the regulatory machinery underlying flowering in Brassica napus, with a focus on selected key flowering time related genes.

The data collected in this study and the analysis pipeline will be made available to the community as the Oilseed Rape Developmental Expression Resource, a web interface which allows the data to be explored in an intuitive and interactive manner.