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1.
Proc Natl Acad Sci U S A ; 110(26): 10848-53, 2013 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-23754401

RESUMO

Laccases, as early as 1959, were proposed to catalyze the oxidative polymerization of monolignols. Genetic evidence in support of this hypothesis has been elusive due to functional redundancy of laccase genes. An Arabidopsis double mutant demonstrated the involvement of laccases in lignin biosynthesis. We previously identified a subset of laccase genes to be targets of a microRNA (miRNA) ptr-miR397a in Populus trichocarpa. To elucidate the roles of ptr-miR397a and its targets, we characterized the laccase gene family and identified 49 laccase gene models, of which 29 were predicted to be targets of ptr-miR397a. We overexpressed Ptr-MIR397a in transgenic P. trichocarpa. In each of all nine transgenic lines tested, 17 PtrLACs were down-regulated as analyzed by RNA-seq. Transgenic lines with severe reduction in the expression of these laccase genes resulted in an ∼40% decrease in the total laccase activity. Overexpression of Ptr-MIR397a in these transgenic lines also reduced lignin content, whereas levels of all monolignol biosynthetic gene transcripts remained unchanged. A hierarchical genetic regulatory network (GRN) built by a bottom-up graphic Gaussian model algorithm provides additional support for a role of ptr-miR397a as a negative regulator of laccases for lignin biosynthesis. Full transcriptome-based differential gene expression in the overexpressed transgenics and protein domain analyses implicate previously unidentified transcription factors and their targets in an extended hierarchical GRN including ptr-miR397a and laccases that coregulate lignin biosynthesis in wood formation. Ptr-miR397a, laccases, and other regulatory components of this network may provide additional strategies for genetic manipulation of lignin content.


Assuntos
Regulação para Baixo/genética , Lacase/genética , MicroRNAs/genética , MicroRNAs/metabolismo , Populus/enzimologia , Populus/genética , RNA de Plantas/genética , RNA de Plantas/metabolismo , Sequência de Bases , Regulação Enzimológica da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Redes Reguladoras de Genes , Genes de Plantas , Lacase/antagonistas & inibidores , Lignina/antagonistas & inibidores , Lignina/química , Lignina/metabolismo , Filogenia , Proteínas de Plantas/genética
2.
Science ; 381(6654): 216-221, 2023 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-37440632

RESUMO

The domestication of forest trees for a more sustainable fiber bioeconomy has long been hindered by the complexity and plasticity of lignin, a biopolymer in wood that is recalcitrant to chemical and enzymatic degradation. Here, we show that multiplex CRISPR editing enables precise woody feedstock design for combinatorial improvement of lignin composition and wood properties. By assessing every possible combination of 69,123 multigenic editing strategies for 21 lignin biosynthesis genes, we deduced seven different genome editing strategies targeting the concurrent alteration of up to six genes and produced 174 edited poplar variants. CRISPR editing increased the wood carbohydrate-to-lignin ratio up to 228% that of wild type, leading to more-efficient fiber pulping. The edited wood alleviates a major fiber-production bottleneck regardless of changes in tree growth rate and could bring unprecedented operational efficiencies, bioeconomic opportunities, and environmental benefits.


Assuntos
Edição de Genes , Lignina , Populus , Madeira , Carboidratos/análise , Lignina/genética , Madeira/genética , Sistemas CRISPR-Cas , Populus/genética , Papel , Crescimento Sustentável
3.
Nat Commun ; 10(1): 3548, 2019 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-31391460

RESUMO

Microbial fermentation of lignocellulosic biomass to produce industrial chemicals is exacerbated by the recalcitrant network of lignin, cellulose and hemicelluloses comprising the plant secondary cell wall. In this study, we show that transgenic poplar (Populus trichocarpa) lines can be solubilized without any pretreatment by the extreme thermophile Caldicellulosiruptor bescii that has been metabolically engineered to shift its fermentation products away from inhibitory organic acids to ethanol. Carbohydrate solubilization and conversion of unpretreated milled biomass is nearly 90% for two transgenic lines, compared to only 25% for wild-type poplar. Unexpectedly, unpretreated intact poplar stems achieved nearly 70% of the fermentation production observed with milled poplar as the substrate. The nearly quantitative microbial conversion of the carbohydrate content of unpretreated transgenic lignocellulosic biomass bodes well for full utilization of renewable biomass feedstocks.


Assuntos
Clostridiales/metabolismo , Fermentação , Microbiologia Industrial , Engenharia Metabólica , Populus/metabolismo , Biomassa , Celulose/metabolismo , Clostridiales/genética , Etanol/metabolismo , Lignina/metabolismo , Plantas Geneticamente Modificadas/química , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Polissacarídeos/metabolismo , Populus/química , Populus/genética
4.
Nat Commun ; 9(1): 1579, 2018 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-29679008

RESUMO

A multi-omics quantitative integrative analysis of lignin biosynthesis can advance the strategic engineering of wood for timber, pulp, and biofuels. Lignin is polymerized from three monomers (monolignols) produced by a grid-like pathway. The pathway in wood formation of Populus trichocarpa has at least 21 genes, encoding enzymes that mediate 37 reactions on 24 metabolites, leading to lignin and affecting wood properties. We perturb these 21 pathway genes and integrate transcriptomic, proteomic, fluxomic and phenomic data from 221 lines selected from ~2000 transgenics (6-month-old). The integrative analysis estimates how changing expression of pathway gene or gene combination affects protein abundance, metabolic-flux, metabolite concentrations, and 25 wood traits, including lignin, tree-growth, density, strength, and saccharification. The analysis then predicts improvements in any of these 25 traits individually or in combinations, through engineering expression of specific monolignol genes. The analysis may lead to greater understanding of other pathways for improved growth and adaptation.


Assuntos
Lignina/biossíntese , Lignina/genética , Populus/genética , Madeira/química , Madeira/fisiologia , Regulação da Expressão Gênica de Plantas , Plantas Geneticamente Modificadas/genética , Populus/metabolismo , Transcriptoma/genética , Árvores/genética , Árvores/metabolismo , Xilema/metabolismo
5.
J Colloid Interface Sci ; 363(1): 206-12, 2011 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-21840015

RESUMO

Ultrathin films of cellulose nanocrystals (CNCs) are obtained by using a convective assembly setup coupled with a low-strength external AC electric field. The orientation and degree of alignment of the rod-like nanoparticles are controlled by the applied field strength and frequency used during film formation. Calculated dipole moments and Clausius-Mossotti factors allowed the determination of the critical frequencies, the peak dielectrophoresis as well as the principal orientation of the CNCs in the ultrathin films. As a result of the combination of shear forces and low electric field highly ultrathin films with controlled, unprecedented CNC alignment are achieved.


Assuntos
Algoritmos , Celulose/química , Campos Eletromagnéticos , Eletroforese , Membranas Artificiais , Nanopartículas/química , Tamanho da Partícula , Propriedades de Superfície
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