Transition studies 

 in plants             by Rolf Baumberger 

R2R3MYB2 Transcription Factor (Draft)

Suppose one focuses on one single MYB-TF, namely the main transcription factor in anthocyanin accumulation R2R3MYB2 in Diplacus flowers. In that case, the exon code is similar in all varieties and ecotypes. The real difference lies in
a) the on/off switch
b) the STRs affecting color density
c) the splicing site shaping color hue
At all these sites, biased mutations could explain their existence. In other words, specialized molecules (coding or noncoding RNAs) could force those changeovers under environmental constraints.



Under epigenetic control, these listed strings can go from an active state to a passive state and vice versa.

TATA box: GA(T/C)AG (G/C)CAAAAAGA(T/C)AAATAAAAA  (active T or G/passive C)

STRs: n(TA)  n--> 10 active; 


n <--10 passive


Ear motif: GAAATGAT active; -------- passive

observed in Genomes of Diplacus: 

grandiflorus, australis, longiflorus, australis, parviflorus, aridus, puniceus, clevelandii, calycinus & aurantiacus & "rutilus = RUT". see: NCBI

Any biased mutation altering the regulatory site strings affects the phenotype on an individual basis and is up to 1000 times more frequent than regular mutations.


A possible function of R2R3MYB4 Factor

After MYB4 bombardment of epidermal cells of yellow D. australis flowers. The vacuoles are bluish and orange-tinged.


Applying Virus silenced R2R3MYb4 factor: The shape becomes dwarf, and the red basal anthocyanin pigment is missing. --> Transcription factor MYB4 affects the floral size and basal floral pigment constitution.

At the splicing site in MYB4, various delets and inserts of different lengths are observed. Depending on the Diplacus variety, the "indels" might interchange dynamically. The goal behind this could be to alter floral color and size.