Constitutive expression of Arabidopsis MYB transcription factor, AtMYB11, in tobacco modulates flavonoid biosynthesis in favor of flavonol accumulation.

KEY MESSAGE: Heterologous expression of AtMYB11 , a flavonol-specific transcription factor from Arabidopsis , in tobacco modulates flavonoid biosynthesis, however, with a lower efficiency as compared to its paralogs AtMYB12 and AtMYB111. Transcriptional regulation is the most important means for controlling flavonoid biosynthesis under temporal and spatial cues. In Arabidopsis, three functionally redundant MYB transcription factors (AtMYB11, AtMYB111 and AtMYB12) have been characterized as flavonol-specific regulators which positively modulate expression of biosynthetic genes involved in flavonol biosynthesis. Based on expression of AtMYB111 and AtMYB12 in heterologous systems, studies suggest that these transcription factors can be used to develop plants with enhanced flavonol biosynthesis. The potential of AtMYB11 to activate flavonol biosynthesis in a heterologous system has not yet been studied. In this study, the regulatory potential of AtMYB11 has been studied in Nicotiana tabacum by developing transgenic plants constitutively expressing AtMYB11. Our analysis using leaf and petal tissues of the transgenic plants indicates that AtMYB11 enhances flavonol and chlorogenic acid (CGA) biosynthesis in tobacco through up-regulation of the biosynthetic genes. Activation of flavonol biosynthesis in tobacco by AtMYB11 is not as pronounced as with AtMYB12 or AtMYB111. Taken together, these results reveal a differential regulatory mechanism in plants for modulating flavonol biosynthesis. This study demonstrated that AtMYB11 can be strategically used for enhancing the health beneficial flavonols in species other than Arabidopsis.