Altered lignin biosynthesis using biotechnology to improve lignocellulosic biofuel feedstocks

Poovaiah, Charleson R.; Nageswara-Rao, Madhugiri; Soneji, Jaya R.; Baxter, Holly L.; Stewart, C. Neal

doi:10.1111/pbi.12225

Cited by 98 publications

(54 citation statements)

References 120 publications

(164 reference statements)

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“…Figure 1 shows a typical structural model of lignin. Gymnosperms contain almost entirely G unit in lignins; dicotyledonous angiosperms contain G and S units in lignins; and all the G, S, and H units can be found in monocotyledonous lignins [5]. Other units with relatively fewer contents were also identified in the lignin of LCBM, such as ferulates and coumarates [6].…”

Section: Introductionmentioning

confidence: 99%

Structural Characterization of Lignin and Its Degradation Products with Spectroscopic Methods

Hong-qin

et al. 2017

Journal of Spectroscopy

256

103

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Lignin is highly branched phenolic polymer and accounts 15-30% by weight of lignocellulosic biomass (LCBM). The acceptable molecular structure of lignin is composed with three main constituents linked by different linkages. However, the structure of lignin varies significantly according to the type of LCBM, and the composition of lignin strongly depends on the degradation process. Thus, the elucidation of structural features of lignin is important for the utilization of lignin in high efficient ways. Up to date, degradation of lignin with destructive methods is the main path for the analysis of molecular structure of lignin. Spectroscopic techniques can provide qualitative and quantitative information on functional groups and linkages of constituents in lignin as well as the degradation products. In this review, recent progresses on lignin degradation were presented and compared. Various spectroscopic methods, such as ultraviolet spectroscopy, Fourier-transformed infrared spectroscopy, Raman spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy, for the characterization of structural and compositional features of lignin were summarized. Various NMR techniques, such as 1 H, 13 C, 19 F, and 31 P, as well as 2D NMR, were highlighted for the comprehensive investigation of lignin structure. Quantitative 13 C NMR and various 2D NMR techniques provide both qualitative and quantitative results on the detailed lignin structure and composition produced from various processes which proved to be ideal methods in practice.

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Section: Introductionmentioning

confidence: 99%

Structural Characterization of Lignin and Its Degradation Products with Spectroscopic Methods

Hong-qin

et al. 2017

Journal of Spectroscopy

256

103

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“…Many studies using T-DNA insertion mutagenesis and RNA interference technologies showed the knock-out/knock-down of genes involved in lignin biosynthesis resulting in a considerable reduction (10%-50%) of overall lignin content of the transgenic plants [67]. The lignin reduction in plant biomass often comes with a fitness cost, which might compromise the plant's ability to withstand biotic and abiotic stresses.…”

Section: Reducing the Lignin Content/altering The Composition For Easmentioning

confidence: 99%

“…The lignin reduction in plant biomass often comes with a fitness cost, which might compromise the plant's ability to withstand biotic and abiotic stresses. These genetically engineered low lignin plants are often weak and produce lower total biomass due to the lack of lignin deposition in structural cells like xylem, tracheary elements and vessels [67]. Additionally, genetic engineering of lignin can affect related secondary metabolite biosynthesis (flavonoids, coumarins and phenolic compounds), influencing normal plant growth and development [67].…”

Section: Reducing the Lignin Content/altering The Composition For Easmentioning

confidence: 99%

“…These genetically engineered low lignin plants are often weak and produce lower total biomass due to the lack of lignin deposition in structural cells like xylem, tracheary elements and vessels [67]. Additionally, genetic engineering of lignin can affect related secondary metabolite biosynthesis (flavonoids, coumarins and phenolic compounds), influencing normal plant growth and development [67]. Hence, the lignin bioengineering must take these issues into account for designing the genetic engineering strategies.…”

Section: Reducing the Lignin Content/altering The Composition For Easmentioning

confidence: 99%

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Engineering Plant Biomass Lignin Content and Composition for Biofuels and Bioproducts

et al. 2015

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Abstract:Lignin is an aromatic biopolymer involved in providing structural support to plant cell walls. Compared to the other cell wall polymers, i.e., cellulose and hemicelluloses, lignin has been considered a hindrance in cellulosic bioethanol production due to the complexity involved in its separation from other polymers of various biomass feedstocks. Nevertheless, lignin is a potential source of valuable aromatic chemical compounds and upgradable building blocks. Though the biosynthetic pathway of lignin has been elucidated in great detail, the random nature of the polymerization (free radical coupling) process poses challenges for its depolymerization into valuable bioproducts. The absence of specific methodologies for lignin degradation represents an important opportunity for research and development. This review highlights research development in lignin biosynthesis, lignin genetic engineering and different biological and chemical means of depolymerization used to convert lignin into biofuels and bioproducts. OPEN ACCESSEnergies 2015, 8 7655

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“…Lignin, a heterogeneous phenolic polymer comprised of p-hydroxyphenyl (H), guaiacyl (G) and syringyl (S) monomer units, interacts with cell wall polysaccharides to form a complex structure that is resistant to enzymatic breakdown (Boerjan et al 2003). Several greenhouse and field experiments have shown that cell wall saccharification and biofuel yields of switchgrass and other biofuel feedstocks can be significantly improved by manipulating the lignin biosynthetic pathway (Baxter et al 2015;Poovaiah et al 2014). One approach is to reduce the expression of a single gene in the lignin biosynthetic pathway, as demonstrated by switchgrass plants with downregulated caffeic acid O-methyltransferase (COMT), an enzyme primarily involved in S-lignin synthesis.…”

Section: Introductionmentioning

confidence: 99%

Hybridization of downregulated-COMT transgenic switchgrass lines with field-selected switchgrass for improved biomass traits

et al. 2016

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Transgenic switchgrass (Panicum virgatum L.) has been produced for improved cell walls for biofuels. For instance, downregulated caffeic acid 3-O-methyltransferase (COMT) switchgrass produced significantly more biomass and biofuel than the nontransgenic progenitor line. In the present study we sought to further improve biomass characteristics by crossing the downregulated COMT T 1 lines with highyielding switchgrass accessions in two genetic backgrounds ('Alamo' and 'Kanlow'). Crosses and T 2 progeny analyses were made under greenhouse conditions to assess maternal effects, plant morphology and yield, and cell wall traits. Female parent type influenced morphology, but had no effect on cell wall traits. T 2 hybrids produced with T 1 COMTdownregulated switchgrass as the female parent were taller, produced more tillers, and produced 63 % more biomass compared with those produced using the field selected accession as the female parent. Transgene status (presence or absence of transgene) influenced both growth and cell wall traits. T 2 transgenic hybrids were 7 % shorter 80 days after sowing and produced 43 % less biomass than non-transgenic null-segregant hybrids. Cell wall-related differences included lower lignin content, reduced syringyl-to-guaiacyl (S/G) lignin monomer ratio, and a 12 % increase in total sugar release in the T 2 transgenic hybrids compared to non-transgenic null segregants. This is the first study to evaluate the feasibility of transferring the lowrecalcitrance traits associated with a transgenic switchgrass line into high-yielding field varieties in an attempt to improve growth-related traits. Our Holly L. Baxter and Lisa W. Alexander have equally contributed. results provide insights into the possible improvement of switchgrass productivity via biotechnology paired with plant breeding.

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Altered lignin biosynthesis using biotechnology to improve lignocellulosic biofuel feedstocks

Cited by 98 publications

References 120 publications

Structural Characterization of Lignin and Its Degradation Products with Spectroscopic Methods

Structural Characterization of Lignin and Its Degradation Products with Spectroscopic Methods

Engineering Plant Biomass Lignin Content and Composition for Biofuels and Bioproducts

Hybridization of downregulated-COMT transgenic switchgrass lines with field-selected switchgrass for improved biomass traits

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