Transition studies 

 in plants             by Rolf Baumberger 

 Diplacus Analyses III

An intact MBW complex largely controls anthocyanin synthesis.


The MYB-TF is the central element here. The coding of this factor is practically identical in all Diplacus varieties. The CD (conservative domain) is shown in red. The gaps on the right, the "ear motif," must not be missing when the complex is active.

Part of the MYB anthocyanin activator  protein 

Without this insertion, anthocyanin synthesis is prevented (MYB rep) and favored with insertion (GAAATGAT).

Active and inactive MB(W) complexes

In addition, the “TATATA” strings within the first and second introns of MYB act like a tuning knob, i.e., the longer they are, the more active this MBW complex is. 

more? click on the pic 

The hairpin loops in orange flowers are shorter than red flowers but longer in 

yellow ones. In F1 flowers, one would expect long and short hairpins altogether.

Respective enzyme complexes actively control both processes. These, in turn, are dependent on environmental signals. Both the Ear motif and the STRs can be inherited. They are probably generated ad hoc by enzyme complexes and incorporated into the genome.

This effect can be observed and determined by crossing experiments. T27 and T30 are two plants from the transition zone. Their flower coloring is lighter colored at the start. The longer the plants are observed (years), the redder the flowers become. 

In 2002, this long-lived plant had light yellow-orange 

flowers and became orange-red in 2022.

Similar can also be observed genotypically. One crosses TxT (inbred line) measures the color and plots all in the Lab space. This process is repeated after 14 years. A color shift towards red is also observed genetically. 

  • T27_02s
  • T27_16s

These processes override Mendel's rules in a transition zone. Mendel's rules only apply again when the process has come to an end. Even selection has hardly any influence. It is overridden a thousandfold. An additional gene flow is unnecessary: all genes are already present..
Please note: This is only one described complex of about 50 necessary to transform the flower color and shape. (confirmed hypothesis)

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