Ectopic expression of MYB46 identifies transcriptional regulatory genes in secondary wall biosynthesis in Arabidopsis

MYB46 functions as a transcriptional switch that turns on the genes necessary for secondary wall biosynthesis. Elucidating the transcriptional regulatory network immediately downstream of MYB46 is crucial to our understanding of the molecular and biochemical processes involved in the biosynthesis and deposition of secondary walls in plants. The transcription factors identified here may include direct activators of secondary wall biosynthesis genes. The current study discovered novel hierarchical relationships among the transcription factors involved in the transcriptional regulation of secondary wall biosynthesis and generated several testable hypotheses. To gain insights into the MYB46-mediated transcriptional regulation, we first established an inducible secondary wall thickening system in Arabidopsis by expressing MYB46 under the control of dexamethasone inducible promoter. Then, we used ATH1 GeneChip microarray to obtain a series of time-course transcriptome profiles with regard to the induction of secondary wall development.