Biomass formation and sugar release efficiency of Populus modified by altered expression of a NAC transcription factor

Woody biomass is an important feedstock for biofuel production. Manipulation of wood properties that enable efficient conversion of biomass to biofuel reduces cost of biofuel production. Wood cell wall composition is regulated at several levels that involve expression of transcription factors such as wood-/secondary cell wall- associated NAC domains (WND or SND). In Arabidopsis thaliana, SND1 regulates cell wall composition through activation of its down-stream targets such as MYBs. The functional aspects of SND1 homologs in the woody Populus have been studied through transgenic manipulation. In this study, we investigated the role of PdWND1B, Populus SND1 sequence ortholog, in wood formation using transgenic manipulation through over-expression or silencing under the control of a vascular-specific 4-coumarate-CoA ligase (4CL) promoter. As compared to control plants, PdWND1B-RNAi plants were shorter in height, with significantly reduced stem diameter and dry biomass, whereas there were no significant differences in growth and productivity of PdWND1B over-expression plants. Conversely, PdWND1B over-expression lines showed a significant reduction in cellulose and increase in lignin content, whereas there was no significant impact on lignin content of down-regulated lines. Stem carbohydrate composition analysis revealed a decrease in glucose, mannose, arabinose, and galactose, but an increase in xylose in the over-expression lines. Transcriptome analysis revealed upregulation of several downstream transcription factors and secondary cell wall related structural genes in the PdWND1B over-expression lines that corresponded to significant phenotypic changes in cell wall chemistry observed in PdWND1B overexpression lines. Relative to the control, glucose release and ethanol production from stem biomass was significantly reduced in over-expression lines but appeared enhanced in the RNAi lines. Our results show that PdWND1B is an important factor determining biomass productivity, cell wall chemistry and its conversion to biofuels in Populus.

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Distinct and Overlapping Functions of Miscanthus sinensis MYB Transcription Factors SCM1 and MYB103 in Lignin Biosynthesis

International Journal of Molecular Sciences ◽

10.3390/ijms222212395 ◽

2021 ◽

Vol 22 (22) ◽

pp. 12395

Author(s):

Philippe Golfier ◽

Olga Ermakova ◽

Faride Unda ◽

Emily K. Murphy ◽

Jianbo Xie ◽

...

Keyword(s):

Cell Wall ◽

Transcription Factors ◽

Secondary Cell Wall ◽

Target Genes ◽

Lignin Content ◽

Ectopic Expression ◽

Lignin Biosynthesis ◽

Miscanthus Sinensis ◽

Growth Stages ◽

Transcriptional Responses

Cell wall recalcitrance is a major constraint for the exploitation of lignocellulosic biomass as a renewable resource for energy and bio-based products. Transcriptional regulators of the lignin biosynthetic pathway represent promising targets for tailoring lignin content and composition in plant secondary cell walls. However, knowledge about the transcriptional regulation of lignin biosynthesis in lignocellulosic feedstocks, such as Miscanthus, is limited. In Miscanthus leaves, MsSCM1 and MsMYB103 are expressed at growth stages associated with lignification. The ectopic expression of MsSCM1 and MsMYB103 in N. benthamiana leaves was sufficient to trigger secondary cell wall deposition with distinct sugar and lignin compositions. Moreover, RNA-seq analysis revealed that the transcriptional responses to MsSCM1 and MsMYB103 overexpression showed an extensive overlap with the response to the NAC master transcription factor MsSND1, but were distinct from each other, underscoring the inherent complexity of secondary cell wall formation. Furthermore, conserved and previously described promoter elements as well as novel and specific motifs could be identified from the target genes of the three transcription factors. Together, MsSCM1 and MsMYB103 represent interesting targets for manipulations of lignin content and composition in Miscanthus towards a tailored biomass.

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MYB Transcription Factors and Its Regulation in Secondary Cell Wall Formation and Lignin Biosynthesis during Xylem Development

International Journal of Molecular Sciences ◽

10.3390/ijms22073560 ◽

2021 ◽

Vol 22 (7) ◽

pp. 3560

Author(s):

Ruixue Xiao ◽

Chong Zhang ◽

Xiaorui Guo ◽

Hui Li ◽

Hai Lu

Keyword(s):

Cell Wall ◽

Transcription Factors ◽

Secondary Wall ◽

Secondary Cell Wall ◽

Lignin Biosynthesis ◽

Cell Wall Formation ◽

Long Distance ◽

Secondary Cell Wall Formation ◽

Myb Transcription Factors ◽

Wall Formation

The secondary wall is the main part of wood and is composed of cellulose, xylan, lignin, and small amounts of structural proteins and enzymes. Lignin molecules can interact directly or indirectly with cellulose, xylan and other polysaccharide molecules in the cell wall, increasing the mechanical strength and hydrophobicity of plant cells and tissues and facilitating the long-distance transportation of water in plants. MYBs (v-myb avian myeloblastosis viral oncogene homolog) belong to one of the largest superfamilies of transcription factors, the members of which regulate secondary cell-wall formation by promoting/inhibiting the biosynthesis of lignin, cellulose, and xylan. Among them, MYB46 and MYB83, which comprise the second layer of the main switch of secondary cell-wall biosynthesis, coordinate upstream and downstream secondary wall synthesis-related transcription factors. In addition, MYB transcription factors other than MYB46/83, as well as noncoding RNAs, hormones, and other factors, interact with one another to regulate the biosynthesis of the secondary wall. Here, we discuss the biosynthesis of secondary wall, classification and functions of MYB transcription factors and their regulation of lignin polymerization and secondary cell-wall formation during wood formation.

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Change in lignin structure, but not in lignin content, in transgenic poplar overexpressing the rice master regulator of secondary cell wall biosynthesis

Physiologia Plantarum ◽

10.1111/ppl.12684 ◽

2018 ◽

Vol 163 (2) ◽

pp. 170-182 ◽

Cited By ~ 9

Author(s):

Nuoendagula ◽

Yukiko Tsuji ◽

Naoki Takata ◽

Shingo Sakamoto ◽

Akiko Nakagawa‐Izumi ◽

...

Keyword(s):

Cell Wall ◽

Secondary Cell Wall ◽

Lignin Content ◽

Cell Wall Biosynthesis ◽

Transgenic Poplar ◽

Master Regulator ◽

Secondary Cell Wall Biosynthesis ◽

Lignin Structure

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Distinct and overlapping functions of Miscanthus sinensis MYB transcription factors SCM1 and MYB103 in lignin biosynthesis

10.1101/629709 ◽

2019 ◽

Author(s):

Philippe Golfier ◽

Faride Unda ◽

Emily K. Murphy ◽

Jianbo Xie ◽

Feng He ◽

...

Keyword(s):

Cell Wall ◽

Transcriptional Regulation ◽

Secondary Cell Wall ◽

Lignin Content ◽

Lignin Biosynthesis ◽

Miscanthus Sinensis ◽

Cell Wall Formation ◽

Transcriptional Responses ◽

Secondary Cell Wall Formation ◽

Wall Formation

AbstractCell wall recalcitrance is a major constraint for the exploitation of lignocellulosic biomass as renewable resource for energy and bio-based products. Transcriptional regulators of the lignin biosynthetic pathway represent promising targets for tailoring lignin content and composition in plant secondary cell walls. A wealth of research in model organisms has revealed that transcriptional regulation of secondary cell wall formation is orchestrated by a hierarchical transcription factor (TF) network with NAC TFs as master regulators and MYB factors in the lower tier regulators. However, knowledge about the transcriptional regulation of lignin biosynthesis in lignocellulosic feedstocks, such as Miscanthus, is limited. Here, we characterized two Miscanthus MYB TFs, MsSCM1 and MsMYB103, and compared their transcriptional impact with that of the master regulator MsSND1. In Miscanthus leaves MsSCM1 and MsMYB103 are expressed at growth stages associated with lignification. Ectopic expression of MsSCM1 and MsMYB103 in tobacco leaves was sufficient to trigger secondary cell wall deposition with distinct sugar and lignin composition. Moreover, RNA-seq analysis revealed that the transcriptional responses to MsSCM1 and MsMYB103 overexpression showed extensive overlap with the response to MsSND1, but were distinct from each other, underscoring the inherent complexity of secondary cell wall formation. Together, MsSCM1 and MsMYB103 represent interesting targets for manipulations of lignin content and composition in Miscanthus towards tailored biomass.

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Secondary cell wall composition and candidate gene expression in developing willow (Salix purpurea) stems

Planta ◽

10.1007/s00425-014-2034-1 ◽

2014 ◽

Vol 239 (5) ◽

pp. 1041-1053 ◽

Cited By ~ 6

Author(s):

Yongfang Wan ◽

Cristina Gritsch ◽

Theodora Tryfona ◽

Mike J. Ray ◽

Ambrose Andongabo ◽

...

Keyword(s):

Gene Expression ◽

Cell Wall ◽

Candidate Gene ◽

Secondary Cell Wall ◽

Cell Wall Composition ◽

Salix Purpurea

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The in vivo impact of MsLAC1, a Miscanthus laccase isoform, on lignification and lignin composition contrasts with its in vitro substrate preference

BMC Plant Biology ◽

10.1186/s12870-019-2174-3 ◽

2019 ◽

Vol 19 (1) ◽

Author(s):

Feng He ◽

Katja Machemer-Noonan ◽

Philippe Golfier ◽

Faride Unda ◽

Johanna Dechert ◽

...

Keyword(s):

Cell Wall ◽

Transcription Factors ◽

Lignin Content ◽

Lignin Biosynthesis ◽

Lignin Composition ◽

Xylem Fibers ◽

Breeding Target

Abstract Background Understanding lignin biosynthesis and composition is of central importance for sustainable bioenergy and biomaterials production. Species of the genus Miscanthus have emerged as promising bioenergy crop due to their rapid growth and modest nutrient requirements. However, lignin polymerization in Miscanthus is poorly understood. It was previously shown that plant laccases are phenol oxidases that have multiple functions in plant, one of which is the polymerization of monolignols. Herein, we link a newly discovered Miscanthus laccase, MsLAC1, to cell wall lignification. Characterization of recombinant MsLAC1 and Arabidopsis transgenic plants expressing MsLAC1 were carried out to understand the function of MsLAC1 both in vitro and in vivo. Results Using a comprehensive suite of molecular, biochemical and histochemical analyses, we show that MsLAC1 localizes to cell walls and identify Miscanthus transcription factors capable of regulating MsLAC1 expression. In addition, MsLAC1 complements the Arabidopsis lac4–2 lac17 mutant and recombinant MsLAC1 is able to oxidize monolignol in vitro. Transgenic Arabidopsis plants over-expressing MsLAC1 show higher G-lignin content, although recombinant MsLAC1 seemed to prefer sinapyl alcohol as substrate. Conclusions In summary, our results suggest that MsLAC1 is regulated by secondary cell wall MYB transcription factors and is involved in lignification of xylem fibers. This report identifies MsLAC1 as a promising breeding target in Miscanthus for biofuel and biomaterial applications.

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The Arabidopsis Domain of Unknown Function 1218 (DUF1218) Containing Proteins, MODIFYING WALL LIGNIN-1 and 2 (At1g31720/MWL-1 and At4g19370/MWL-2) Function Redundantly to Alter Secondary Cell Wall Lignin Content

PLoS ONE ◽

10.1371/journal.pone.0150254 ◽

2016 ◽

Vol 11 (3) ◽

pp. e0150254 ◽

Cited By ~ 3

Author(s):

Ritesh Mewalal ◽

Eshchar Mizrachi ◽

Berdine Coetzee ◽

Shawn D. Mansfield ◽

Alexander A. Myburg

Keyword(s):

Cell Wall ◽

Unknown Function ◽

Secondary Cell Wall ◽

Lignin Content ◽

Domain Of Unknown Function

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Lignification of spruce tracheid secondary cell walls related to longitudinal hardness and modulus of elasticity using nano-indentation

Canadian Journal of Botany ◽

10.1139/b02-091 ◽

2002 ◽

Vol 80 (10) ◽

pp. 1029-1033 ◽

Cited By ~ 41

Author(s):

W Gindl ◽

H S Gupta ◽

C Grünwald

Keyword(s):

Cell Wall ◽

Modulus Of Elasticity ◽

Cell Walls ◽

Secondary Cell Wall ◽

Lignin Content ◽

Wood Formation ◽

Nano Indentation ◽

Secondary Cell Walls ◽

Cell Wall Development ◽

The One

The lignin content and the mechanical properties of lignifying and fully lignified spruce tracheid secondary cell walls were determined using UV microscopy and nano-indentation, respectively. The average lignin content of developing tracheids was 0.10 g·g1, as compared with 0.21 g·g1 in mature tracheids. The modulus of elasticity of developing cells was on average 22% lower than the one measured in mature, fully lignified cells. For the longitudinal hardness, a larger difference of 26% was observed. As lignifying cells in the cambial zone are undergoing cell wall development, spaces in the cellulosehemicellulose structure are filled with lignin and the density of the cell wall is believed to increase. It is therefore suggested that the observed difference in modulus of elasticity between developing and fully lignified cell walls is due to the filling of spaces with lignin and an increase of the packing density of the cell wall during lignification. Although remarkably less stiff than the composite polysaccharide structure in the secondary cell wall, lignin may be considered equally hard. Therefore, the observed increase in lignin content may contribute directly to the measured increase of hardness.Key words: secondary cell wall, hardness, lignin, modulus of elasticity, wood formation.

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