Dataset Information

A Novel NAC Transcription Factor From Eucalyptus, EgNAC141, Positively Regulates Lignin Biosynthesis and Increases Lignin Deposition.

ABSTRACT: Wood formation is a complicated process under the control of a large set of transcription factors. NAC transcription factors are considered "master switches" in this process. However, few NAC members have been cloned and characterized in Eucalyptus, which is one of the most economically important woody plants. Here, we reported an NAC transcription factor from Eucalyptus grandis, EgNAC141, which has no Arabidopsis orthologs associated with xylogenesis-related processes. EgNAC141 was predominantly expressed in lignin-rich tissues, such as the stem and xylem. Overexpression of EgNAC141 in Arabidopsis resulted in stronger lignification, larger xylem, and higher lignin content. The expression of lignin biosynthetic genes in transgenic plants was significantly higher compared with wild-type plants. The transient expression of EgNAC141 activated the expression of Arabidopsis lignin biosynthetic genes in a dual-luciferase assay. Overall, these results showed that EgNAC141 is a positive regulator of lignin biosynthesis and may help us understand the regulatory mechanism of wood formation.

SUBMITTER: Sun Y

PROVIDER: S-EPMC8061705 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature

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A Novel NAC Transcription Factor From Eucalyptus, EgNAC141, Positively Regulates Lignin Biosynthesis and Increases Lignin Deposition.

Sun YiMing Y Jiang Chunxue C Jiang Ruiqi R Wang Fengying F Zhang Zhenguo Z Zeng Jianjun J

Frontiers in plant science 20210408

Wood formation is a complicated process under the control of a large set of transcription factors. NAC transcription factors are considered "master switches" in this process. However, few NAC members have been cloned and characterized in Eucalyptus, which is one of the most economically important woody plants. Here, we reported an NAC transcription factor from Eucalyptus grandis, EgNAC141, which has no Arabidopsis orthologs associated with xylogenesis-related processes. EgNAC141 ...[more]

PMID: 33897732

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Project description:The NAC transcription factors play important roles in regulating plant growth, development, and senescence, and responding to biotic and abiotic stressors in plants. A novel coding sequence (1,059 bp) was cloned from hexaploid triticale in this study. The putative protein (352 amino acids) encoded by this sequence was over 95% similar to the amino acid sequence of a NAC protein from Aegilops tauschii (XP020161331), and it formed a clade with Ae. tauschii, durum wheat, and barley. The putative protein contained a conserved nature actomyosin (NAM) domain (129 consecutive amino acids) between the 20th and 148th amino acids at the N-terminus and three transcription activation regions at the C-terminus. The novel gene was identified as a triticale NAC gene localized in the nucleus and designated as TwNAC01 (GenBank accession MG736919). The expression levels of TwNAC01 were the highest in roots, followed by leaves and stems when triticale lines were exposed to drought, polyethylene glycol 6,000 (PEG6000), NaCl, cold, methyl jasmonate (MeJA), and abscisic acid (ABA). Transgenic Arabidopsis thaliana overexpressing TwNAC01 had significantly lower leaf water loss rates and longer roots than wild-type (WT) A. thaliana. Virus-induced silencing of the TwNAC01 gene in triticale delayed root development and decreased length of primary root. Under drought stress, leaves of TwNAC01-silenced triticale had higher levels of malondialdehyde (MDA) and hydrogen peroxide (H2O2), but lower relative water content (RWC), net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, and transpiration rate than the leaves of the WT. Gene overexpression and silencing experiments suggested that TwNAC01 improves plant stress tolerance by increasing root length, regulating the water content of plant leaves by reducing MDA and H2O2 content, and adjusting respiration rate. The results suggest that TwNAC01 is a novel NAC transcription factor gene that can be exploited for triticale and cereal improvement.

Project description:BackgroundNAC domain transcription factors initiate secondary cell wall biosynthesis in Arabidopsis fibres and vessels by activating numerous transcriptional regulators and biosynthetic genes. NAC family member SND2 is an indirect target of a principal regulator of fibre secondary cell wall formation, SND1. A previous study showed that overexpression of SND2 produced a fibre cell-specific increase in secondary cell wall thickness in Arabidopsis stems, and that the protein was able to transactivate the cellulose synthase8 (CesA8) promoter. However, the full repertoire of genes regulated by SND2 is unknown, and the effect of its overexpression on cell wall chemistry remains unexplored.ResultsWe overexpressed SND2 in Arabidopsis and analyzed homozygous lines with regards to stem chemistry, biomass and fibre secondary cell wall thickness. A line showing upregulation of CesA8 was selected for transcriptome-wide gene expression profiling. We found evidence for upregulation of biosynthetic genes associated with cellulose, xylan, mannan and lignin polymerization in this line, in agreement with significant co-expression of these genes with native SND2 transcripts according to public microarray repositories. Only minor alterations in cell wall chemistry were detected. Transcription factor MYB103, in addition to SND1, was upregulated in SND2-overexpressing plants, and we detected upregulation of genes encoding components of a signal transduction machinery recently proposed to initiate secondary cell wall formation. Several homozygous T4 and hemizygous T1 transgenic lines with pronounced SND2 overexpression levels revealed a negative impact on fibre wall deposition, which may be indirectly attributable to excessive overexpression rather than co-suppression. Conversely, overexpression of SND2 in Eucalyptus stems led to increased fibre cross-sectional cell area.ConclusionsThis study supports a function for SND2 in the regulation of cellulose and hemicellulose biosynthetic genes in addition of those involved in lignin polymerization and signalling. SND2 seems to occupy a subordinate but central tier in the secondary cell wall transcriptional network. Our results reveal phenotypic differences in the effect of SND2 overexpression between woody and herbaceous stems and emphasize the importance of expression thresholds in transcription factor studies.

Dataset Information

A Novel NAC Transcription Factor From Eucalyptus, EgNAC141, Positively Regulates Lignin Biosynthesis and Increases Lignin Deposition.

Publications

A Novel NAC Transcription Factor From <i>Eucalyptus</i>, EgNAC141, Positively Regulates Lignin Biosynthesis and Increases Lignin Deposition.

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