A Battery of Transcription Factors Involved in the Regulation of Secondary Cell Wall Biosynthesis in Arabidopsis

Abstract

SECONDARY WALL-ASSOCIATED NAC DOMAIN PROTEIN1 (SND1) is a master transcriptional switch activating the developmental program of secondary wall biosynthesis. Here, we demonstrate that a battery of SND1-regulated transcription factors is required for normal secondary wall biosynthesis in Arabidopsis thaliana. The expression of 11 SND1-regulated transcription factors, namely, SND2, SND3, MYB103, MYB85, MYB52, MYB54, MYB69, MYB42, MYB43, MYB20, and KNAT7 (a Knotted1-like homeodomain protein), was developmentally associated with cells undergoing secondary wall thickening. Of these, dominant repression of SND2, SND3, MYB103, MYB85, MYB52, MYB54, and KNAT7 significantly reduced secondary wall thickening in fiber cells. Overexpression of SND2, SND3, and MYB103 increased secondary wall thickening in fibers, and overexpression of MYB85 led to ectopic deposition of lignin in epidermal and cortical cells in stems. Furthermore, SND2, SND3, MYB103, MYB85, MYB52, and MYB54 were able to induce secondary wall biosynthetic genes. Direct target analysis using the estrogen-inducible system revealed that MYB46, SND3, MYB103, and KNAT7 were direct targets of SND1 and also of its close homologs, NST1, NST2, and vessel-specific VND6 and VND7. Together, these results demonstrate that a transcriptional network consisting of SND1 and its downstream targets is involved in regulating secondary wall biosynthesis in fibers and that NST1, NST2, VND6, and VND7 are functional homologs of SND1 that regulate the same downstream targets in different cell types.

Genetic architecture of wood properties based on association analysis and co‐expression networks in white spruce

“…In Arabidopsis , SND2 and SND3, the closest homolog to PgNAC‐8 , have been shown to regulate secondary cell wall CesA genes (Zhong et al ., 2008). Taken together, these results point to a network involving NAC and MYB regulators that regulate secondary cell wall properties and influence EW traits most strongly, which was suggested to change over the course of a growing season.…”

KNOX genes: versatile regulators of plant development and diversity

“…We highlight the discovery of a novel class of KNOX genes that lack a homeobox and insights into KN1 protein trafficking in plants (Box 2). We also discuss recent work in the unicellular green alga Chlamydomonas reinhardtii that suggests ancestral KNOX genes controlled diploid development and diversified in land plants in order to control multicellular body plans (Lee et al, 2008). Finally, we consider how evolutionary changes in KNOX gene regulation may have influenced plant diversity.…”

“…Class I KNOX genes are most similar to kn1 and are expressed in overlapping domains within the SAMs of both monocot and eudicot plants (see Glossary, Box 1) (Hake et al, 2004;Jackson et al, 1994). Class II KNOX genes form a monophyletic group that is distinct from Class I genes, and show diverse expression patterns and few known functions (Zhong et al, 2008). We therefore focus this review on Class I KNOX genes.…”

Changes in cell wall polysaccharide composition, gene transcription and alternative splicing in germinating barley embryos

“…A cascade TF regulations exist with NAC domain TFs acting as master switches and MYB TFs servicing as second-level regulators (Taylor-Teeples et al , 2015, Zhong et al , 2010, Zhong et al , 2008. Barley genome contains at least 52 NAC and 119 MYB domain TF genes (Supplemental Table S10).…”