Influence of silicon on polymerization process during lignin synthesis. Implications for cell wall properties

Radotić, Ksenija; Đikanović, Daniela; Kalauzi, Aleksandar; Tanasijević, Gordana; Maksimović, Vuk; Maksimović, Jelena Dragišić

doi:10.1016/j.ijbiomac.2021.12.143

Cited by 12 publications

(13 citation statements)

References 60 publications

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“…When Si binds to the phenoxy radicals and/or quinone methide of the dehydrodimers, it may inhibit the lignin C–O–C ether interunit linkages, which would interrupt their polymerization into larger lignin fragments. Such activity is consistent with XPS results, and also with published data showing that during lignin-like polymer synthesis, silicic acid binding to phenylpropanoid dimers slows down their polymerization into larger fragments, resulting in an altered polymer structure …”

Section: Resultssupporting

confidence: 92%

“…The reduction in binding energy could be a result of the formation of Si–O–C bonds that are weaker due to the lower electronegativity of Si in relation to C. 31 The reduction in peak intensity may indicate a lower abundance of C–O–C ether linkages in the lignin–silica copolymers, possibly indicating that the lignin-like units become shorter with the increased silicic acid. 38 …”

Section: Resultsmentioning

confidence: 99%

“…Such activity is consistent with XPS results, and also with published data showing that during ligninlike polymer synthesis, silicic acid binding to phenylpropanoid dimers slows down their polymerization into larger fragments, resulting in an altered polymer structure. 38 Thermogravimetric analyses (TGA) supported structural changes in lignin as a result of lignin−silica interactions (Figure 6). To avoid the influence of loosely bound water molecules, TGA graphs were normalized at 120 °C.…”

Section: Formation Of Silica Affects Lignin Propertiesmentioning

confidence: 86%

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Silica Biomineralization with Lignin Involves Si–O–C Bonds That Stabilize Radicals

Palakurthy,

Houben,

Elbaum

et al. 2024

Biomacromolecules

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Plants undergo substantial biomineralization of silicon, which is deposited primarily in cell walls as amorphous silica. The mineral formation could be moderated by the structure and chemistry of lignin, a polyphenol polymer that is a major constituent of the secondary cell wall. However, the reactions between lignin and silica have not yet been well elucidated. Here, we investigate silica deposition onto a lignin model compound. Polyphenyl propanoid was synthesized from coniferyl alcohol by oxidative coupling with peroxidase in the presence of acidic tetramethyl orthosilicate, a silicic acid precursor. Raman, Fourier transform infrared, and X-ray photoelectron spectroscopies detected changes in lignin formation in the presence of silicic acid. Bonds between the Si−O/Si−OH residues and phenoxyl radicals and lignin functional groups formed during the first 3 h of the reaction, while silica continued to form over 3 days. Thermal gravimetric analysis indicated that lignin yields increased in the presence of silicic acid, possibly via the stabilization of phenolic radicals. This, in turn, resulted in shorter stretches of the lignin polymer. Silica deposition initiated within a lignin matrix via the formation of covalent Si−O−C bonds. The silica nucleants grew into 2−5 nm particles, as observed via scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy. Additional silica precipitated into an extended gel. Collectively, our results demonstrate a reciprocal relation by which lignin polymerization catalyzes the formation of silica, and at the same time silicic acid enhances lignin polymerization and yield.

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Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Section: Formation Of Silica Affects Lignin Propertiesmentioning

confidence: 86%

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Silica Biomineralization with Lignin Involves Si–O–C Bonds That Stabilize Radicals

Palakurthy,

Houben,

Elbaum

et al. 2024

Biomacromolecules

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“…Raman microspectroscopy could show that monolignols were trapped in the forming silica, and the extent of lignin polymerization was limited. Reduction in lignin polymer length is typical to synthetic lignin which is polymerized in the presence of silicic acid ( Radotić et al., 2022 ). Such reduction suggests inhibited formation β-O-4 ether linkage, which is the most prevalent bond between monolignols ( Boerjan et al., 2003 ).…”

Section: Discussionmentioning

confidence: 99%

Deposition of silica in sorghum root endodermis modifies the chemistry of associated lignin

Zexer,

Diehn,

Elbaum

2024

Front. Plant Sci.

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Silica aggregates at the endodermis of sorghum roots. Aggregation follows a spotted pattern of locally deposited lignin at the inner tangential cell walls. Autofluorescence microscopy suggests that non-silicified (-Si) lignin spots are composed of two distinct concentric regions of varied composition. To highlight variations in lignin chemistry, we used Raman microspectroscopy to map the endodermal cell wall and silica aggregation sites in sorghum roots grown hydroponically with or without Si amendment. In +Si samples, the aggregate center was characterized by typical lignin monomer bands surrounded by lignin with a low level of polymerization. Farther from the spot, polysaccharide concentration increased and soluble silicic acid was detected in addition to silica bands. In -Si samples, the main band at the spot center was assigned to lignin radicals and highly polymerized lignin. Both +Si and -Si loci were enriched by aromatic carbonyls. We propose that at silica aggregation sites, carbonyl rich lignin monomers are locally exported to the apoplast. These monomers are radicalized and polymerized into short lignin polymers. In the presence of silicic acid, bonds typically involved in lignin extension, bind to silanols and nucleate silica aggregates near the monomer extrusion loci. This process inhibits further polymerization of lignin. In -Si samples, the monomers diffuse farther in the wall and crosslink with cell wall polymers, forming a ring of dense lignified cell wall around their export sites.

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“…The oligomer profiles have been analyzed using Reverse phase high‐performance liquid chromatography‐mass spectrometry (RP‐HPLC‐MS) chromatography as described in our previous investigation. [ 21 ] Briefly, reversed‐phase separation had been used along with a single quadrupole detector operating in scan and single ion recording mode. Besides MS, all analyses have been monitored by the diode array detector, so we have used both data/chromatograms for the creation of oligomeric profiles of DHP and each reaction time.…”

Section: Methodsmentioning

confidence: 99%

Two‐way reaction of versatile peroxidase with artificial lignin enhances low‐molecular weight fractions

Spasojević,

Prodanović,

Mutavdžić

et al. 2023

Biotechnology Journal

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In recent years, versatile peroxidase (VP) has emerged as a promising enzyme for biotechnological applications, as it can oxidize lignin without the external mediators. To gain insights into the breakdown process of artificial lignin by VP, reaction between the two was studied. Degradation products were fractionated using ultrafiltration and analyzed by RP‐ high performance liquid chromatography with mass detection (HPLC‐MS) chromatography. Four fractions were obtained based on their molecular sizes: >10, 3–10, 1–3, and <1 kDa. Interestingly, while VP did not significantly alter the yields of these fractions, the chromatograms revealed the presence of oligomers with different molecular weights (MWs) resulting from the enzymatic activity. The VP exhibits a dual role in its enzymatic activity: both degrading and synthesizing these oligomers. This was confirmed by principal component analysis (PCA). The positive correlations were found between certain oligomers (D1 and D2, D5 and D6, as well as between D7, D10, T2, and T4), suggesting their simultaneous degradation. On the other hand, a negative correlation was found between the monomer and some oligomers (D7, D10, T2, and T4), indicating the decomposition of these oligomers into monomers. These findings shed light on the intricate interplay between VP and artificial lignin, offering valuable insights for potential applications in lignin valorization.

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Influence of silicon on polymerization process during lignin synthesis. Implications for cell wall properties

Cited by 12 publications

References 60 publications

Silica Biomineralization with Lignin Involves Si–O–C Bonds That Stabilize Radicals

Silica Biomineralization with Lignin Involves Si–O–C Bonds That Stabilize Radicals

Deposition of silica in sorghum root endodermis modifies the chemistry of associated lignin

Two‐way reaction of versatile peroxidase with artificial lignin enhances low‐molecular weight fractions

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