Impact of the Brown-Midrib <i>bm</i>5 Mutation on Maize Lignins

Summary Wood, also called secondary xylem, is a specialized vascular tissue constituted by different cell types that undergo a differentiation process involving deposition of thick, lignified secondary cell walls. The mechanisms needed to control the extent of lignin deposition depending on the cell type and the differentiation stage are far from being fully understood. We found that the Eucalyptus transcription factor EgMYB1, which is known to repress lignin biosynthesis, interacts specifically with a linker histone variant, EgH1.3. This interaction enhances the repression of EgMYB1's target genes, strongly limiting the amount of lignin deposited in xylem cell walls. The expression profiles of EgMYB1 and EgH1.3 overlap in xylem cells at early stages of their differentiation as well as in mature parenchymatous xylem cells, which have no or only thin lignified secondary cell walls. This suggests that a complex between EgMYB1 and EgH1.3 integrates developmental signals to prevent premature or inappropriate lignification of secondary cell walls, providing a mechanism to fine‐tune the differentiation of xylem cells in time and space. We also demonstrate a role for a linker histone variant in the regulation of a specific developmental process through interaction with a transcription factor, illustrating that plant linker histones have other functions beyond chromatin organization.

show abstract

“…Lignin structure was evaluated using the simplified thioacidolysis method recently described by Méchin et al . ().…”

Section: Methodsmentioning

confidence: 97%

The Eucalyptus linker histone variant EgH1.3 cooperates with the transcription factor EgMYB1 to control lignin biosynthesis during wood formation

et al. 2016

Self Cite

View full text Add to dashboard Cite

show abstract

“…Thioacidolysis : Thioacidolysis of lignins (5 mg) was performed according to a reported method by using heneicosane (C 21 H 44 , Fluka) as an internal standard (IS). Lignin‐derived p ‐hydroxyphenyl (H), guaiacyl (G), and syringyl (S) thioacidolysis monomers were analyzed as their trimethylsilyl derivatives by a GC–MS instrument (Saturn 2100, Varian) equipped with a poly(dimethylsiloxane) column (30 m×0.25 mm; SPB‐1, Supelco) and using the following heating program: 40 to 180 °C at 30 °C min −1 , then 180 to 260 °C at 2 °C min −1 .…”

Section: Methodsmentioning

confidence: 99%

Imidazolium‐Based Ionic Liquids as Efficient Reagents for the C−O Bond Cleavage of Lignin

et al. 2017

Self Cite

View full text Add to dashboard Cite

The demethylation of lignin in ionic liquids (ILs) was investigated by using pure lignin model monomers and dimers together with dioxane-isolated lignins from poplar, miscanthus, and maize. Different methylimidazolium ILs were compared and the samples were treated with two different heating processes: microwave irradiation and conventional heating in a sealed tube. The conversion yield and influence of the treatment on the lignin structure were assessed by P NMR spectroscopy, size-exclusion chromatography, and thioacidolysis. The acidic methylimidazolium IL [HMIM]Br was shown to be an effective combination of solvent and reagent for the demethylation and depolymerization of lignin. The relatively mild reaction conditions, the clean work-up, and the ability to reuse the IL makes the described procedure an attractive and new green method for the conversion of lignin to produce phenol-rich lignin oligomers.

show abstract

“…KL was measured according to the standard procedure, starting from 350 mg of extractive-free CW residue (Méchin et al, 2014). The ASL was measured spectrophotometrically as described previously (Dence, 1992).…”

Section: Cw Analysismentioning

confidence: 99%

Different Routes for Conifer- and Sinapaldehyde and Higher Saccharification upon Deficiency in the Dehydrogenase CAD1

Déjardin²,

et al. 2017

Self Cite

View full text Add to dashboard Cite

In the search for renewable energy sources, genetic engineering is a promising strategy to improve plant cell wall composition for biofuel and bioproducts generation. Lignin is a major factor determining saccharification efficiency and, therefore, is a prime target to engineer. Here, lignin content and composition were modified in poplar (Populus tremula 3 Populus alba) by specifically down-regulating CINNAMYL ALCOHOL DEHYDROGENASE1 (CAD1) by a hairpin-RNA-mediated silencing approach, which resulted in only 5% residual CAD1 transcript abundance. These transgenic lines showed no biomass penalty despite a 10% reduction in Klason lignin content and severe shifts in lignin composition. Nuclear magnetic resonance spectroscopy and thioacidolysis revealed a strong increase (up to 20-fold) in sinapaldehyde incorporation into lignin, whereas coniferaldehyde was not increased markedly. Accordingly, ultra-high-performance liquid chromatography-mass spectrometry-based phenolic profiling revealed a more than 24,000-fold accumulation of a newly identified compound made from 8-8 coupling of two sinapaldehyde radicals. However, no additional cinnamaldehyde coupling products could be detected in the CAD1-deficient poplars. Instead, the transgenic lines accumulated a range of hydroxycinnamate-derived metabolites, of which the most prominent accumulation (over 8,500-fold) was observed for a compound that was identified by purification and nuclear magnetic resonance as syringyl lactic acid hexoside. Our data suggest that, upon down-regulation of CAD1, coniferaldehyde is converted into ferulic acid and derivatives, whereas sinapaldehyde is either oxidatively coupled into S9(8-8)S9 and lignin or converted to sinapic acid and derivatives. The most prominent sink of the increased flux to hydroxycinnamates is syringyl lactic acid hexoside. Furthermore, low-extent saccharification assays, under different pretreatment conditions, showed strongly increased glucose (up to +81%) and xylose (up to +153%) release, suggesting that down-regulating CAD1 is a promising strategy for improving lignocellulosic biomass for the sugar platform industry.

show abstract

Impact of the Brown-Midrib bm5 Mutation on Maize Lignins

Cited by 40 publications

References 33 publications

The Eucalyptus linker histone variant EgH1.3 cooperates with the transcription factor EgMYB1 to control lignin biosynthesis during wood formation

The Eucalyptus linker histone variant EgH1.3 cooperates with the transcription factor EgMYB1 to control lignin biosynthesis during wood formation

Imidazolium‐Based Ionic Liquids as Efficient Reagents for the C−O Bond Cleavage of Lignin

Different Routes for Conifer- and Sinapaldehyde and Higher Saccharification upon Deficiency in the Dehydrogenase CAD1

Contact Info

Product

Resources

About