Expression of Arabidopsis MYB transcription factor, AtMYB111, in tobacco requires light to modulate flavonol content

Flavonoids, due to their pharmacological attributes, have recently become target molecules for metabolic engineering in commonly consumed food crops. Strategies including expression of single genes and gene pyramiding have provided only limited success, due principally to the highly branched and complex biosynthetic pathway of the flavonoids. Transcription factors have been demonstrated as an efficient tool for metabolic engineering of this pathway, but often exhibit variation in heterologous systems relative to that in the homologous system. In the present work, Arabidopsis MYB transcription factor, AtMYB111, has been expressed in tobacco to study whether this can enhance flavonoid biosynthesis in heterologous system. The results suggest that AtMYB111 expression in transgenic tobacco enhances expression of genes of the phenylpropanoid pathway leading to an elevated content of flavonols. However, dark incubation of transgenic and wild type (WT) plants down-regulated both the expression of genes as well as flavonoid content as compared to light grown plants. The study concludes that AtMYB111 can be effectively used in heterologous systems, however, light is required for its action in modulating biosynthetic pathway.