Transition studies in flowering plants

 Rolf Baumberger

Molecular Genetics IV

  • MBWY1
  • MBWred
  • MYBall
  • gauk

Many dynamic changes take place at the molecular regulatory level for a yellow form to develop into a red form through a transition. The MBW complex shown plays a central role. Through the combination and specific regulation, the flower size can also change. It is large-sized for the yellow form and smaller for the red shape.  

If the flower size can easily be explained by up and downregulation of TFs, it becomes much more challenging to pigment the epidermal cells of the flowers. The yellow form has a non-functional MYB1 allele. There are differences in the coding sequence as well as in the cis-coding sequence (promoter). In a yellow way, no pelargonidin is produced in the flowers by this non-functional factor. Pelargonidin gives the floral parts its beautiful red color. Now a process lasting for years takes place, where somatic mutations occur in the epidermis of the flower. A periodically fluctuating rocking up to the new norm (red) takes place. The phenotype, the flowers show a rocking. This means that young flowers are somewhat redder than older ones on the same plant. Every year this juggling shifts slightly into the redder area until no more wobbling can be perceived, and the plant has genetically adapted to the other red individuals. This can take up to 15 years. See more under Molecular genetic aspects 2 (Pu-Pu-factor)

Recently a transcriptome study in Royal Iris was released ( If one could compare almost yellow flowering Iris atropurpurea variants with the already existent transcriptome activity in respect of the anthocyanine regulation, a big step in elucidating the color characterization would be done. -> Iris atropurpurea