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

• Published in: The Plant journal : for cell and molecular biology 2009-11, Vol.60 (4), p.649-665
• Main Authors: Ko, Jae-Heung, Kim, Won-Chan, Han, Kyung-Hwan
• Format: Article
• Language: English
• Subjects: Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Biochemistry; Biological and medical sciences; Biosynthesis; Botany; Cell Wall - metabolism; digital gene expression; DNA, Plant - genetics; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Profiling; Gene Expression Regulation, Developmental; Gene Expression Regulation, Plant; GeneChip; Hypotheses; inducible expression; Molecular and cellular biology; Molecular genetics; MYB46; Oligonucleotide Array Sequence Analysis; Plant physiology and development; Plants, Genetically Modified - genetics; Plants, Genetically Modified - growth & development; Promoter Regions, Genetic; secondary wall biosynthesis; transcription factor; Transcription Factors - genetics; Transcription Factors - metabolism; Transcription. Transcription factor. Splicing. Rna processing; Transcriptional Activation; Transgenic plants
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/j.1365-313x.2009.03989.x

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. To gain insights into 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 an ATH1 GeneChip microarray and Illumina digital gene expression system to obtain a series of transcriptome profiles with regard to the induction of secondary wall development. These analyses allowed us to identify a group of transcription factors whose expression coincided with or preceded the induction of secondary wall biosynthetic genes. A transient transcriptional activation assay was used to confirm the hierarchical relationships among the transcription factors in the network. The in vivo assay showed that MYB46 transcriptionally activates downstream target transcription factors, three of which (AtC3H14, MYB52 and MYB63) were shown to be able to activate secondary wall biosynthesis genes. AtC3H14 activated the transcription of all of the secondary wall biosynthesis genes tested, suggesting that AtC3H14 may be another master regulator of secondary wall biosynthesis. The transcription factors identified here may include direct activators of secondary wall biosynthesis genes. The present study discovered novel hierarchical relationships among the transcription factors involved in the transcriptional regulation of secondary wall biosynthesis, and generated several testable hypotheses.