The MYB46 transcription factor is a direct target of SND1 and regulates secondary wall biosynthesis in Arabidopsis.
We demonstrate that the Arabidopsis thaliana MYB46 transcription factor is a direct target of SECONDARY WALL-ASSOCIATED NAC DOMAIN PROTEIN1 (SND1), which is a key transcriptional activator regulating the developmental program of secondary wall biosynthesis. The MYB46 gene is expressed predominantly in fibers and vessels in stems, and its encoded protein is targeted to the nucleus and can activate transcription. MYB46 gene expression was shown to be regulated by SND1, and transactivation analysis demonstrated that SND1 as well as its close homologs were able to activate the MYB46 promoter. Electrophoretic mobility shift assays and chromatin immunoprecipitation experiments revealed that SND1 binds to the MYB46 promoter. Dominant repression of MYB46 caused a drastic reduction in the secondary wall thickening of fibers and vessels. Overexpression of MYB46 resulted in an activation of the biosynthetic pathways of cellulose, xylan, and lignin and concomitantly led to ectopic deposition of secondary walls in cells that are normally nonsclerenchymatous. In addition, the expression of two secondary wall-associated transcription factors, MYB85 and KNAT7, was highly upregulated by MYB46 overexpression. These results demonstrate that MYB46 is a direct target of SND1 and is another key player in the transcriptional network involved in the regulation of secondary wall biosynthesis in Arabidopsis.
Zhong
Ruiqin
R
Department of Plant Biology, University of Georgia, Athens, GA 30602, USA.
Richardson
Elizabeth A
EA
Ye
Zheng-Hua
ZH
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism* / Q000648:ultrastructure; D047369:Chromatin Immunoprecipitation; D024202:Electrophoretic Mobility Shift Assay; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D019441:Plant Epidermis / Q000166:cytology / Q000378:metabolism; D018515:Plant Leaves / Q000166:cytology / Q000378:metabolism; D018547:Plant Stems / Q000235:genetics; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D021381:Protein Transport; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation; D052584:Xylem / Q000648:ultrastructure
D029681:Arabidopsis Proteins; C572748:KNAT7 protein, Arabidopsis; C525564:Myb46 protein, Arabidopsis; D012097:Repressor Proteins; C517318:SND1 protein, Arabidopsis; D015534:Trans-Activators; D014157:Transcription Factors