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1.
Behav Res Methods ; 2024 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-38918315

RESUMO

EMOKINE is a software package and dataset creation suite for emotional full-body movement research in experimental psychology, affective neuroscience, and computer vision. A computational framework, comprehensive instructions, a pilot dataset, observer ratings, and kinematic feature extraction code are provided to facilitate future dataset creations at scale. In addition, the EMOKINE framework outlines how complex sequences of movements may advance emotion research. Traditionally, often emotional-'action'-based stimuli are used in such research, like hand-waving or walking motions. Here instead, a pilot dataset is provided with short dance choreographies, repeated several times by a dancer who expressed different emotional intentions at each repetition: anger, contentment, fear, joy, neutrality, and sadness. The dataset was simultaneously filmed professionally, and recorded using XSENS® motion capture technology (17 sensors, 240 frames/second). Thirty-two statistics from 12 kinematic features were extracted offline, for the first time in one single dataset: speed, acceleration, angular speed, angular acceleration, limb contraction, distance to center of mass, quantity of motion, dimensionless jerk (integral), head angle (with regards to vertical axis and to back), and space (convex hull 2D and 3D). Average, median absolute deviation (MAD), and maximum value were computed as applicable. The EMOKINE software is appliable to other motion-capture systems and is openly available on the Zenodo Repository. Releases on GitHub include: (i) the code to extract the 32 statistics, (ii) a rigging plugin for Python for MVNX file-conversion to Blender format (MVNX=output file XSENS® system), and (iii) a Python-script-powered custom software to assist with blurring faces; latter two under GPLv3 licenses.

2.
Nature ; 627(8005): 789-796, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38538940

RESUMO

The Antarctic Circumpolar Current (ACC) represents the world's largest ocean-current system and affects global ocean circulation, climate and Antarctic ice-sheet stability1-3. Today, ACC dynamics are controlled by atmospheric forcing, oceanic density gradients and eddy activity4. Whereas palaeoceanographic reconstructions exhibit regional heterogeneity in ACC position and strength over Pleistocene glacial-interglacial cycles5-8, the long-term evolution of the ACC is poorly known. Here we document changes in ACC strength from sediment cores in the Pacific Southern Ocean. We find no linear long-term trend in ACC flow since 5.3 million years ago (Ma), in contrast to global cooling9 and increasing global ice volume10. Instead, we observe a reversal on a million-year timescale, from increasing ACC strength during Pliocene global cooling to a subsequent decrease with further Early Pleistocene cooling. This shift in the ACC regime coincided with a Southern Ocean reconfiguration that altered the sensitivity of the ACC to atmospheric and oceanic forcings11-13. We find ACC strength changes to be closely linked to 400,000-year eccentricity cycles, probably originating from modulation of precessional changes in the South Pacific jet stream linked to tropical Pacific temperature variability14. A persistent link between weaker ACC flow, equatorward-shifted opal deposition and reduced atmospheric CO2 during glacial periods first emerged during the Mid-Pleistocene Transition (MPT). The strongest ACC flow occurred during warmer-than-present intervals of the Plio-Pleistocene, providing evidence of potentially increasing ACC flow with future climate warming.

3.
Br J Psychol ; 115(1): 148-180, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37740117

RESUMO

Theories of human emotion, including some emotion embodiment theories, suggest that our moods and affective states are reflected in the movements of our bodies. We used the reverse process for mood regulation; modulate body movements to regulate mood. Dancing is a type of full-body movement characterized by affective expressivity and, hence, offers the possibility to express different affective states through the same movement sequences. We tested whether the repeated imitation of a dancer performing two simple full-body dance movement sequences with different affective expressivity (happy or sad) could change mood states. Computer-based systems, using avatars as dance models to imitate, offer a series of advantages such as independence from physical contact and location. Therefore, we compared mood induction effects in two conditions: participants were asked to imitate dance movements from one of the two avatars showing: (a) videos of a human dancer model or (b) videos of a robot dancer model. The mood induction was successful for both happy and sad imitations, regardless of condition (human vs. robot avatar dance model). Moreover, the magnitude of happy mood induction and how much participants liked the task predicted work-related motivation after the mood induction. We conclude that mood regulation through dance movements is possible and beneficial in the work context.


Assuntos
Comportamento Imitativo , Intenção , Humanos , Afeto/fisiologia , Emoções/fisiologia , Felicidade , Movimento/fisiologia
4.
Chembiochem ; 24(9): e202300001, 2023 05 02.
Artigo em Inglês | MEDLINE | ID: mdl-36821718

RESUMO

Chemically labile ester linkages can be introduced into lignin by incorporation of monolignol conjugates, which are synthesized in planta by acyltransferases that use a coenzyme A (CoA) thioester donor and a nucleophilic monolignol alcohol acceptor. The presence of these esters facilitates processing and aids in the valorization of renewable biomass feedstocks. However, the effectiveness of this strategy is potentially limited by the low steady-state levels of aromatic acid thioester donors in plants. As part of an effort to overcome this, aromatic acid CoA ligases involved in microbial aromatic degradation were identified and screened against a broad panel of substituted cinnamic and benzoic acids involved in plant lignification. Functional fingerprinting of this ligase library identified four robust, highly active enzymes capable of facile, rapid, and high-yield synthesis of aromatic acid CoA thioesters under mild aqueous reaction conditions mimicking in planta activity.


Assuntos
Coenzima A Ligases , Ligases , Coenzima A Ligases/metabolismo , Lignina/metabolismo , Plantas/metabolismo , Ésteres
5.
Psychol Res ; 87(2): 484-508, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-35385989

RESUMO

The ability to exchange affective cues with others plays a key role in our ability to create and maintain meaningful social relationships. We express our emotions through a variety of socially salient cues, including facial expressions, the voice, and body movement. While significant advances have been made in our understanding of verbal and facial communication, to date, understanding of the role played by human body movement in our social interactions remains incomplete. To this end, here we describe the creation and validation of a new set of emotionally expressive whole-body dance movement stimuli, named the Motion Capture Norming (McNorm) Library, which was designed to reconcile a number of limitations associated with previous movement stimuli. This library comprises a series of point-light representations of a dancer's movements, which were performed to communicate to observers neutrality, happiness, sadness, anger, and fear. Based on results from two validation experiments, participants could reliably discriminate the intended emotion expressed in the clips in this stimulus set, with accuracy rates up to 60% (chance = 20%). We further explored the impact of dance experience and trait empathy on emotion recognition and found that neither significantly impacted emotion discrimination. As all materials for presenting and analysing this movement library are openly available, we hope this resource will aid other researchers in further exploration of affective communication expressed by human bodily movement.


Assuntos
Dança , Humanos , Movimento , Emoções , Felicidade , Medo , Expressão Facial
6.
New Phytol ; 237(1): 251-264, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36196006

RESUMO

Ester-linked p-coumarate (pCA) is a hallmark feature of the secondary cell walls in commelinid monocot plants. It has been shown that pCA groups arise during lignin polymerisation from the participation of monolignol conjugates assembled by p-coumaroyl-CoA:monolignol transferase (PMT) enzymes, members of the BAHD superfamily of acyltransferases. Herein, we report that a eudicot species, kenaf (Hibiscus cannabinus), naturally contains p-coumaroylated lignin in the core tissues of the stems but not in the bast fibres. Moreover, we identified a novel acyltransferase, HcPMT, that shares <30% amino acid identity with known monocot PMT sequences. Recombinant HcPMT showed a preference in enzyme assays for p-coumaroyl-CoA and benzoyl-CoA as acyl donor substrates and sinapyl alcohol as an acyl acceptor. Heterologous expression of HcPMT in hybrid poplar trees led to the incorporation of pCA in lignin, but no improvement in the saccharification potential of the wood. This work illustrates the value in mining diverse plant taxa for new monolignol acyltransferases. Furthermore, the occurrence of pCA outside monocot lineages may represent another example of convergent evolution in lignin structure. This discovery expands textbook views on cell wall biochemistry and provides a new molecular tool for engineering the lignin of biomass feedstock plants.


Assuntos
Lignina , Populus , Lignina/metabolismo , Parede Celular/metabolismo , Aciltransferases/metabolismo , Populus/metabolismo , Coenzima A/análise , Coenzima A/metabolismo
7.
Plant Cell Physiol ; 63(6): 744-754, 2022 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-35275214

RESUMO

The complexity of lignin structure impedes efficient cell wall digestibility. Native lignin is composed of a mixture of three dominant monomers, coupled together through a variety of linkages. Work over the past few decades has demonstrated that lignin composition can be altered through a variety of mutational and transgenic approaches such that the polymer is derived almost entirely from a single monomer. In this study, we investigated changes to lignin structure and digestibility in Arabidopsis thaliana in near-single-monolignol transgenics and mutants and determined whether novel monolignol conjugates, produced by a FERULOYL-CoA MONOLIGNOL TRANSFERASE (FMT) or a p-COUMAROYL-CoA MONOLIGNOL TRANSFERASE (PMT), could be integrated into these novel polymers to further improve saccharification efficiency. Monolignol conjugates, including a new conjugate of interest, p-coumaryl p-coumarate, were successfully integrated into high-H, high-G and high-S lignins in A. thaliana. Regardless of lignin composition, FMT- and PMT-expressing plants produced monolignol ferulates and monolignol p-coumarates, respectively, and incorporated them into their lignin. Through the production and incorporation of monolignol conjugates into near-single-monolignol lignins, we demonstrated that substrate availability, rather than monolignol transferase substrate preference, is the most important determining factor in the production of monolignol conjugates, and lignin composition helps dictate cell wall digestibility.


Assuntos
Arabidopsis , Lignina , Arabidopsis/metabolismo , Parede Celular/metabolismo , Lignina/metabolismo , Transferases/análise , Transferases/metabolismo
8.
Plant Physiol ; 189(1): 37-48, 2022 05 03.
Artigo em Inglês | MEDLINE | ID: mdl-35134228

RESUMO

Plant BAHD acyltransferases perform a wide range of enzymatic tasks in primary and secondary metabolism. Acyl-CoA monolignol transferases, which couple a CoA substrate to a monolignol creating an ester linkage, represent a more recent class of such acyltransferases. The resulting conjugates may be used for plant defense but are also deployed as important "monomers" for lignification, in which they are incorporated into the growing lignin polymer chain. p-Coumaroyl-CoA monolignol transferases (PMTs) increase the production of monolignol p-coumarates, and feruloyl-CoA monolignol transferases (FMTs) catalyze the production of monolignol ferulate conjugates. We identified putative FMT and PMT enzymes in sorghum (Sorghum bicolor) and switchgrass (Panicum virgatum) and have compared their activities to those of known monolignol transferases. The putative FMT enzymes produced both monolignol ferulate and monolignol p-coumarate conjugates, whereas the putative PMT enzymes produced monolignol p-coumarate conjugates. Enzyme activity measurements revealed that the putative FMT enzymes are not as efficient as the rice (Oryza sativa) control OsFMT enzyme under the conditions tested, but the SbPMT enzyme is as active as the control OsPMT enzyme. These putative FMTs and PMTs were transformed into Arabidopsis (Arabidopsis thaliana) to test their activities and abilities to biosynthesize monolignol conjugates for lignification in planta. The presence of ferulates and p-coumarates on the lignin of these transformants indicated that the putative FMTs and PMTs act as functional feruloyl-CoA and p-coumaroyl-CoA monolignol transferases within plants.


Assuntos
Arabidopsis , Oryza , Panicum , Sorghum , Aciltransferases/genética , Aciltransferases/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Lignina/metabolismo , Oryza/metabolismo , Panicum/metabolismo , Sorghum/genética , Sorghum/metabolismo , Transferases
9.
Plant Physiol ; 188(2): 1014-1027, 2022 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-34977949

RESUMO

Poplar (Populus) lignin is naturally acylated with p-hydroxybenzoate ester moieties. However, the enzyme(s) involved in the biosynthesis of the monolignol-p-hydroxybenzoates have remained largely unknown. Here, we performed an in vitro screen of the Populus trichocarpa BAHD acyltransferase superfamily (116 genes) using a wheatgerm cell-free translation system and found five enzymes capable of producing monolignol-p-hydroxybenzoates. We then compared the transcript abundance of the five corresponding genes with p-hydroxybenzoate concentrations using naturally occurring unrelated genotypes of P. trichocarpa and revealed a positive correlation between the expression of p-hydroxybenzoyl-CoA monolig-nol transferase (pHBMT1, Potri.001G448000) and p-hydroxybenzoate levels. To test whether pHBMT1 is responsible for the biosynthesis of monolignol-p-hydroxybenzoates, we overexpressed pHBMT1 in hybrid poplar (Populus alba × P. grandidentata) (35S::pHBMT1 and C4H::pHBMT1). Using three complementary analytical methods, we showed that there was an increase in soluble monolignol-p-hydroxybenzoates and cell-wall-bound monolignol-p-hydroxybenzoates in the poplar transgenics. As these pendent groups are ester-linked, saponification releases p-hydroxybenzoate, a precursor to parabens that are used in pharmaceuticals and cosmetics. This identified gene could therefore be used to engineer lignocellulosic biomass with increased value for emerging biorefinery strategies.


Assuntos
Acilação/genética , Aciltransferases/genética , Aciltransferases/metabolismo , Lignina/biossíntese , Lignina/genética , Populus/genética , Populus/metabolismo , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Plantas Geneticamente Modificadas
10.
Plant Cell Environ ; 45(1): 248-261, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34697825

RESUMO

Ferulate-5-hydroxylase is a key enzyme involved in the conversion of the guaiacyl monolignol to the syringyl monolignol in angiosperms. The monolignol ratio has been proposed to affect biomass recalcitrance and the resistance to plant disease. Stem rot caused by the fungus Sclerotinia sclerotiorum in Brassica napus causes severe losses in its production. To date, there is no information about the effect of the lignin monomer ratio on the resistance to S. sclerotiorum in B. napus. Four dominantly expressed ferulate-5-hydroxylase genes were concertedly knocked out by CRISPR/Cas9 in B. napus, and three mutant lines were generated. The S/G lignin compositional ratio was decreased compared to that of the wild type based on the results of Mӓule staining and 2D-NMR profiling in KO-7. The resistance to S. sclerotiorum in stems and leaves increased for the three f5h mutant lines compared with WT. Furthermore, we found that the stem strength of f5h mutant lines was significantly increased. Overall, we demonstrate for the first time that decreasing the S/G ratio by knocking out of the F5H gene improves S. sclerotiorum resistance in B. napus and increases stem strength.


Assuntos
Ascomicetos/patogenicidade , Brassica napus/genética , Brassica napus/microbiologia , Doenças das Plantas/microbiologia , Proteínas de Plantas/genética , Brassica napus/metabolismo , Sistemas CRISPR-Cas , Parede Celular/química , Parede Celular/genética , Resistência à Doença/genética , Regulação da Expressão Gênica de Plantas , Técnicas de Inativação de Genes , Genoma de Planta , Lignina/metabolismo , Família Multigênica , Mutação , Doenças das Plantas/genética , Proteínas de Plantas/metabolismo , Caules de Planta/citologia , Caules de Planta/genética , Plantas Geneticamente Modificadas
11.
Plant Biotechnol J ; 19(9): 1878-1886, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-33949064

RESUMO

To what degree can the lignin subunits in a monocot be derived from monolignol ferulate (ML-FA) conjugates? This simple question comes with a complex set of variables. Three potential requirements for optimizing ML-FA production are as follows: (1) The presence of an active FERULOYL-CoA MONOLIGNOL TRANSFERASE (FMT) enzyme throughout monolignol production; (2) Suppression or elimination of enzymatic pathways competing for monolignols and intermediates during lignin biosynthesis; and (3) Exclusion of alternative phenolic compounds that participate in lignification. A 16-fold increase in lignin-bound ML-FA incorporation was observed by introducing an AsFMT gene into Brachypodium distachyon. On its own, knocking out the native p-COUMAROYL-CoA MONOLIGNOL TRANSFERASE (BdPMT) pathway that competes for monolignols and the p-coumaroyl-CoA intermediate did not change ML-FA incorporation, nor did partial loss of CINNAMOYL-CoA REDUCTASE1 (CCR1) function, which reduced metabolic flux to monolignols. However, stacking AsFMT into the Bdpmt-1 mutant resulted in a 32-fold increase in ML-FA incorporation into lignin over the wild-type level.


Assuntos
Brachypodium , Brachypodium/genética , Lignina , Proteínas de Plantas/genética , Transferases
12.
Plant Direct ; 4(9): e00265, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33005856

RESUMO

Lignin is a key secondary cell wall chemical constituent, and is both a barrier to biomass utilization and a potential source of bioproducts. The Arabidopsis transcription factors MYB58 and MYB63 have been shown to upregulate gene expression of the general phenylpropanoid and monolignol biosynthetic pathways. The overexpression of these genes also results in dwarfism. The vascular integrity, soluble phenolic profiles, cell wall lignin, and transcriptomes associated with these MYB-overexpressing lines were characterized. Plants with high expression of MYB58 and MYB63 had increased ectopic lignin and the xylem vessels were regular and open, suggesting that the stunted growth is not associated with loss of vascular conductivity. MYB58 and MYB63 overexpression lines had characteristic soluble phenolic profiles with large amounts of monolignol glucosides and sinapoyl esters, but decreased flavonoids. Because loss of function lac4 lac17 mutants also accumulate monolignol glucosides, we hypothesized that LACCASE overexpression might decrease monolignol glucoside levels in the MYB-overexpressing plant lines. When laccases related to lignification (LAC4 or LAC17) were co-overexpressed with MYB63 or MYB58, the dwarf phenotype was rescued. Moreover, the overexpression of either LAC4 or LAC17 led to wild-type monolignol glucoside levels, as well as wild-type lignin levels in the rescued plants. Transcriptomes of the rescued double MYB63-OX/LAC17-OX overexpression lines showed elevated, but attenuated, expression of the MYB63 gene itself and the direct transcriptional targets of MYB63. Contrasting the dwarfism from overabundant monolignol production with dwarfism from lignin mutants provides insight into some of the proposed mechanisms of lignin modification-induced dwarfism.

13.
ChemSusChem ; 13(8): 1922, 2020 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-32285625

RESUMO

Invited for this month's cover is the research team from the D.O.E. Great Lake Bioenergy Research Center (GLBRC) at the University of Wisconsin-Madison. The cover image shows how a diverse team with expertise in many different fields works together in an integrated fashion to address complex problems. Only when the whole system, from field to the liquid fuels and co-products, is assessed, can we identify the key parameters needed to design an economically viable biorefinery-based economy. Cover art by Chelsea Mamott. The Full Paper itself is available at 10.1002/cssc.201903345.

14.
ChemSusChem ; 13(8): 2012-2024, 2020 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-31984673

RESUMO

The hydroxycinnamic acids p-coumaric acid (pCA) and ferulic acid (FA) add diversity to the portfolio of products produced by using grass-fed lignocellulosic biorefineries. The level of lignin-bound pCA in Zea mays was modified by the alteration of p-coumaroyl-CoA monolignol transferase expression. The biomass was processed in a lab-scale alkaline-pretreatment biorefinery process and the data were used for a baseline technoeconomic analysis to determine where to direct future research efforts to couple plant design to biomass utilization processes. It is concluded that future plant engineering efforts should focus on strategies that ramp up accumulation of one type of hydroxycinnamate (pCA or FA) predominantly and suppress that of the other. Technoeconomic analysis indicates that target extraction titers of one hydroxycinnamic acid need to be >50 g kg-1 biomass, at least five times higher than observed titers for the impure pCA/FA product mixture from wild-type maize. The technical challenge for process engineers is to develop a viable process that requires more than 80 % reduction of the isolation costs.

15.
Am J Vet Res ; 80(11): 995-1000, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31644346

RESUMO

OBJECTIVE: To compare glucose concentrations in peripheral venous and capillary blood samples collected from dogs before and after consumption of a meal and measured with a veterinary-specific portable blood glucose meter (PBGM). ANIMALS: 12 dogs (96 blood samples). PROCEDURES: A veterinary-specific PBGM was used to measure blood glucose concentrations. Glucose concentrations in capillary blood samples obtained from the carpal pad, medial aspect of a pinna, and oral mucosa were compared with glucose concentrations in blood samples obtained from a lateral saphenous vein. Samples were collected after food was withheld for 12 hours and again 2 hours after consumption of a meal. RESULTS: Location of capillary blood collection had a significant effect on glucose concentrations measured with the PBGM. Glucose concentration in capillary blood collected from the medial aspect of the pinna did not differ significantly from the glucose concentration in peripheral venous blood samples, whereas glucose concentrations in blood samples collected from the carpal pad and oral mucosa differed significantly from the glucose concentration in peripheral venous blood samples. There was no significant difference between preprandial and postprandial blood glucose concentrations. CONCLUSIONS AND CLINICAL RELEVANCE: Glucose concentrations in capillary blood collected from the medial aspect of the pinna of dogs better reflected glucose concentrations in venous blood than concentrations measured in capillary blood collected from the carpal pad or oral mucosa.


Assuntos
Glicemia/análise , Coleta de Amostras Sanguíneas/veterinária , Cães/sangue , Animais , Coleta de Amostras Sanguíneas/métodos , Ingestão de Alimentos , Feminino , Masculino , Período Pós-Prandial
16.
Curr Opin Biotechnol ; 56: 69-74, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30347315

RESUMO

Lignin is a highly abundant polymer in plant cell walls that is essential for land plants' ability to stand upright and transport water. Inside plant cells, lignin monomers, called monolignols, are made from phenylalanine via a multistep pathway. In the cell wall, monomers move freely, until they encounter stationary oxidative enzymes that determine where the lignin polymer forms. However, it remains unclear how lignin monomers are trafficked from inside the cell to the cell wall. Although multiple lines of circumstantial evidence implicate transporters, additional possible mechanisms include the diffusion of monomers across lipid bilayers and the release of monolignol glucosides stored in vacuoles. There are therefore potentially diverse and overlapping mechanisms of monolignol export.


Assuntos
Transporte Biológico , Parede Celular/metabolismo , Lignina/metabolismo , Plantas/metabolismo , Parede Celular/química , Glucosídeos/metabolismo , Células Vegetais/metabolismo , Plantas/classificação , Plantas/enzimologia
17.
Plant Physiol ; 175(3): 1058-1067, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28894022

RESUMO

The cell walls of leaf base tissues of the Canary Island date palm (Phoenix canariensis) contain lignins with the most complex compositions described to date. The lignin composition varies by tissue region and is derived from traditional monolignols (ML) along with an unprecedented range of ML conjugates: ML-acetate, ML-benzoate, ML-p-hydroxybenzoate, ML-vanillate, ML-p-coumarate, and ML-ferulate. The specific functions of such complex lignin compositions are unknown. However, the distribution of the ML conjugates varies depending on the tissue region, indicating that they may play specific roles in the cell walls of these tissues and/or in the plant's defense system.


Assuntos
Lignina/metabolismo , Phoeniceae/metabolismo , Folhas de Planta/metabolismo , Parede Celular/metabolismo , Cromatografia em Gel , Lignina/isolamento & purificação , Espectroscopia de Ressonância Magnética , Espanha
18.
Biotechnol Biofuels ; 10: 109, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28469705

RESUMO

BACKGROUND: The cell wall polymer lignin provides structural support and rigidity to plant cell walls, and therefore to the plant body. However, the recalcitrance associated with lignin impedes the extraction of polysaccharides from the cell wall to make plant-based biofuels and biomaterials. The cell wall digestibility can be improved by introducing labile ester bonds into the lignin backbone that can be easily broken under mild base treatment at room temperature. The FERULOYL-CoA MONOLIGNOL TRANSFERASE (FMT) enzyme, which may be naturally found in many plants, uses feruloyl-CoA and monolignols to synthesize the ester-linked monolignol ferulate conjugates. A mutation in the first lignin-specific biosynthetic enzyme, CINNAMOYL-CoA REDUCTASE (CCR), results in an increase in the intracellular pool of feruloyl-CoA. RESULTS: Maize (Zea mays) has a native putative FMT enzyme, and its ccr mutants produce an increased pool of feruloyl-CoA that can be used for conversion to monolignol ferulate conjugates. The decreased lignin content and monomers did not, however, impact the plant growth or biomass. The increase in monolignol conjugates correlated with an improvement in the digestibility of maize stem rind tissue. CONCLUSIONS: Together, increased monolignol ferulates and improved digestibility in ccr1 mutant plants suggests that they may be superior biofuel crops.

19.
Plant Physiol ; 174(2): 1028-1036, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28416705

RESUMO

Many land plants evolved tall and sturdy growth habits due to specialized cells with thick lignified cell walls: tracheary elements that function in water transport and fibers that function in structural support. The objective of this study was to define how and when diverse cell populations contribute lignin precursors, monolignols, to secondary cell walls during lignification of the Arabidopsis (Arabidopsis thaliana) inflorescence stem. Previous work demonstrated that, when lignin biosynthesis is suppressed in fiber and tracheary element cells with thickened walls, fibers become lignin-depleted while vascular bundles still lignify, suggesting that nonlignifying neighboring xylem cells are contributing to lignification. In this work, we dissect the contributions of different cell types, specifically xylary parenchyma and fiber cells, to lignification of the stem using cell-type-specific promoters to either knock down an essential monolignol biosynthetic gene or to introduce novel monolignol conjugates. Analysis of either reductions in lignin in knockdown lines, or the addition of novel monolignol conjugates, directly identifies the xylary parenchyma and fiber cell populations that contribute to the stem lignification and the developmental timing at which each contribution is most important.


Assuntos
Arabidopsis/citologia , Arabidopsis/metabolismo , Lignina/metabolismo , Caules de Planta/citologia , Caules de Planta/metabolismo , Biomassa , Vias Biossintéticas , Metabolismo dos Carboidratos , Parede Celular/metabolismo , Regulação da Expressão Gênica de Plantas , Técnicas de Silenciamento de Genes , Regiões Promotoras Genéticas , Xilema/citologia , Xilema/metabolismo
20.
Plant Physiol ; 173(2): 998-1016, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27940492

RESUMO

Lignin is a phenolic heteropolymer that is deposited in secondary-thickened cell walls, where it provides mechanical strength. A recent structural characterization of cell walls from monocot species showed that the flavone tricin is part of the native lignin polymer, where it is hypothesized to initiate lignin chains. In this study, we investigated the consequences of altered tricin levels on lignin structure and cell wall recalcitrance by phenolic profiling, nuclear magnetic resonance, and saccharification assays of the naturally silenced maize (Zea mays) C2-Idf (inhibitor diffuse) mutant, defective in the CHALCONE SYNTHASE Colorless2 (C2) gene. We show that the C2-Idf mutant produces highly reduced levels of apigenin- and tricin-related flavonoids, resulting in a strongly reduced incorporation of tricin into the lignin polymer. Moreover, the lignin was enriched in ß-ß and ß-5 units, lending support to the contention that tricin acts to initiate lignin chains and that, in the absence of tricin, more monolignol dimerization reactions occur. In addition, the C2-Idf mutation resulted in strikingly higher Klason lignin levels in the leaves. As a consequence, the leaves of C2-Idf mutants had significantly reduced saccharification efficiencies compared with those of control plants. These findings are instructive for lignin engineering strategies to improve biomass processing and biochemical production.


Assuntos
Aciltransferases/genética , Flavonoides/metabolismo , Inativação Gênica , Lignina/metabolismo , Zea mays/enzimologia , Zea mays/genética , Aciltransferases/metabolismo , Biomassa , Parede Celular/metabolismo , Regulação para Baixo/genética , Regulação da Expressão Gênica de Plantas , Espectroscopia de Ressonância Magnética , Redes e Vias Metabólicas/genética , Mutação/genética , Fenóis/metabolismo , Fenótipo , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Caules de Planta/crescimento & desenvolvimento , Caules de Planta/metabolismo , Zea mays/crescimento & desenvolvimento
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