The MYB46 Transcription Factor Is a Direct Target of SND1 and Regulates Secondary Wall Biosynthesis in Arabidopsis

Abstract

We demonstrate that the Arabidopsis thaliana MYB46 transcription factor is a direct target of SECONDARY WALL-ASSOCI-ATED 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.

MYB transcription factor genes as regulators for plant responses: an overview

“…AtMYB58, AtMYB63 and AtMYB85 activated lignin biosynthesis in fibers and/or vessels (Zhou et al 2009). AtMYB46 is found to be a positive regulator of lignin biosynthesis in fibers and vessels and also regulated cellulose and xylan deposition (Zhong et al 2007). AtMYB26/ MS35 controlled secondary wall deposition in anthers (Yang et al 2007).…”

Arabidopsis VASCULAR-RELATED NAC-DOMAIN6 Directly Regulates the Genes That Govern Programmed Cell Death and Secondary Wall Formation during Xylem Differentiation

“…In particular, genes encoding cellulose synthases that function specifically in the synthesis of the secondary cell wall, including CESA4/IRX5, CESA7/IRX3, and CESA8/IRX1 (Taylor et al, 2003), were upregulated by both VND6 and SND1 (see Supplemental Data Set 1 online). Secondary wall synthesis is regulated by a number of MYB transcription factors (Zhong et al, 2007(Zhong et al, , 2008Zhou et al, 2009). In our experiments, MYB46, MYB83, and MYB103 were upregulated by VND6 and SND1 (see Supplemental Data Set 1 online).…”

“…Molecular studies of SND1 indicated that a network of transcription factors function downstream of SND1 and finally lead to secondary cell wall formation (Zhong et al, 2007(Zhong et al, , 2008Zhou et al, 2009). SND1 directly regulates the expression of genes encoding the transcription factors MYB46, MYB83, MYB103, SND3, and KNAT7 (Zhong et al, 2007;McCarthy et al, 2009).…”

“…SND1 directly regulates the expression of genes encoding the transcription factors MYB46, MYB83, MYB103, SND3, and KNAT7 (Zhong et al, 2007;McCarthy et al, 2009). MYB46 and MYB83 are specifically expressed in fiber and vessel cells, which form secondary cell walls.…”

Respuesta transcripcional de Populus a bifenilos policlorados: Aspectos aplicados a la fitorremediación

“…En plantas, algunos factores de transcripción MYB participan en la activación de genes de respuesta a estrés biótico (Hirayama y Shinozaki, 2010), tales como infección por patógenos (Vailleau et al, 2002); en la regulación del metabolismo primario y secundario, como el control de la acumulación de flavonoles (Stracke et al, 2007), biosíntesis de antocianinas (González et al, 2008), el desarrollo del polen (Preston et al, 2004), la biosíntesis de lignina (Newman et al, 2004;Zhou et al, 2009;Zhong et al, 2007Zhong et al, , 2008 y la apertura estomática (Liang et al, 2005), entre otras. Sin embargo también se ha encontrado su participación en mecanismos de respuesta a estrés abiótico (Alves et al, 2015;.…”