The evolutionary divergence of the genetic networks that control flowering in distinct species

In nature there is a big variation in the way flowers are arranged in inflorescences on a plant. Some species like tulips make solitary flowers, but most others generate complex structures with multiple flowers, known as inflorescences. The inflorescence of the model plant Arabidopsis is a raceme in which flowers develop on the flank of the indeterminate stem, while in petunia, a cymes, the main stem terminates into a flower and growth continues from a newly formed lateral meristem. Many of the genes involved in the development of racemes and cymes are orthologous and encode identical and interchangeable proteins but differ greatly in the time and place where they operate. It is thought that such differences in the regulation of genes are an important factor that led to morphological diversity. In this thesis we determine how such differences arose during evolution through a detailed analysis of one of the genes that play a crucial role in flower development, DOUBLE TOP (DOT). DOT specifies floral meristem identity and thereby controls the time and position where flowers appear on the inflorescence.