Desirable plant cell wall traits for higher-quality miscanthus lignocellulosic biomass

Additional file 7. Box and whisker plots showing the distribution of biomass compositional measurements, and the P-values of t tests used to discriminate between genotypes with high or low saccharification efficiency indices

A cell wall reference profile for Miscanthus bioenergy crops highlights compositional and structural variations associated with development and organ origin

Miscanthus spp. are promising lignocellulosic energy crops, but cell wall recalcitrance to deconstruction still hinders their widespread use as bioenergy and biomaterial feedstocks. Identification of cell wall characteristics desirable for biorefining applications is crucial for lignocellulosic biomass improvement. However, the task of scoring biomass quality is often complicated by the lack of a reference for a given feedstock. A multidimensional cell wall analysis was performed to generate a reference profile for leaf and stem biomass from several miscanthus genotypes harvested at three developmentally distinct time points. A comprehensive suite of 155 monoclonal antibodies was used to monitor changes in distribution, structure and extractability of noncellulosic cell wall matrix glycans. Glycan microarrays complemented with immunohistochemistry elucidated the nature of compositional variation, and in situ distribution of carbohydrate epitopes. Key observations demonstrated that there are crucial differences in miscanthus cell wall glycomes, which may impact biomass amenability to deconstruction. For the first time, variations in miscanthus cell wall glycan components were comprehensively characterized across different harvests, organs and genotypes, to generate a representative reference profile for miscanthus cell wall biomass. Ultimately, this portrait of the miscanthus cell wall will help to steer breeding and genetic engineering strategies for the development of superior energy crops

Trafficking of Xylan to Plant Cell Walls

Plant cell walls are classified as primary and secondary walls. The primary wall is necessary for plant morphogenesis and supports cell growth and expansion. Once the growth and expansion ceases, specialized cells form secondary walls in order to give strength and rigidity to the plant. Secondary cell walls are the main constituent of woody biomass. This biomass is raw material for industrial products, food, and biomaterials. Recently, there are an increasing number of studies using biomass for biofuel production and this area has gained importance. However, there are still many unknowns regarding the synthesis and structure of complex polysaccharides forming biomass. Cellulose, being one of the main components of the cell wall, is synthesized at the plasma membrane by cellulose synthase complexes and does not require transportation. On the other hand, pectin and hemicelluloses are synthesized by enzymes located in the Golgi apparatus. Therefore, they need to be transported to the plasma membrane. Even though this transport mechanism is very important, it is one of the least understood parts of the endomembrane system. Xylan is the major hemicellulose in many biomasses and is important for renewable material production. There is limited knowledge about the cellular trafficking of xylan. In this review, we cover the current information and what we know about the vesicular transport of xylan to the cell wall

Cell Wall Glycan Changes in Different Brachypodium Tissues Give Insights into Monocot Biomass

The annual temperate grass Brachypodium distachyon has become a model system for monocot biomass crops and for understanding lignocellulosic recalcitrance to employ better saccharification and fermentation approaches. It is a monocot plant used to study the grass cell walls that differ from the cell walls of dicot plants such as the eudicot model Arabidopsis. The B. distachyon cell wall is predominantly composed of cellulose, arabinoxylans, and mixed-linkage glucans, and it resembles the cell walls of other field grasses. It has a vascular bundle anatomy similar to C3 grasses. These features make Brachypodium an ideal model to study cell walls. Cell walls are composed of polymers with complex structures that vary between cell types and at different developmental stages. Antibodies that recognize specific cell wall components are currently one of the most effective and specific molecular probes to determine the location and distribution of polymers in plant cell walls in situ. Here, we investigated the glycan distribution in the cell walls of the root and leaf tissues of Brachypodium by employing cell-wall-directed antibodies against diverse glycan epitopes. There are distinct differences in the presence of the epitopes between the root and leaf tissues as well as in the cell type level, which gives insights into monocot biomass

Changes in the abundance of cell wall apiogalacturonan and xylogalacturonan and conservation of rhamnogalacturonan II structure during the diversification of the Lemnoideae

AVCI, UTKU/0000-0001-5355-9906; Pena, Maria J./0000-0002-1672-0067WOS: 000427700100012PubMed: 29288327Main conclusion the diversification of the Lemnoideae was accompanied by a reduction in the abundance of cell wall apiogalacturonan and an increase in xylogalacturonan whereas rhamnogalacturonan II structure and cross-linking are conserved. the subfamily Lemnoideae is comprised of five genera and 38 species of small, fast-growing aquatic monocots. Lemna minor and Spirodela polyrhiza belong to this subfamily and have primary cell walls that contain large amounts of apiogalacturonan and thus are distinct from the primary walls of most other flowering plants. However, the pectins in the cell walls of other members of the Lemnoideae have not been investigated. Here, we show that apiogalacturonan decreased substantially as the Lemnoideae diversified since Wolffiella and Wolffia walls contain between 63 and 88% less apiose than Spirodela, Landoltia, and Lemna walls. in Wolffia, the most derived genus, xylogalacturonan is far more abundant than apiogalacturonan, whereas in Wolffiella pectic polysaccharides have a high arabinose content, which may arise from arabinan sidechains of RG I. the apiose-containing pectin rhamnogalacturonan II (RG-II) exists in Lemnoideae walls as a borate cross-linked dimer and has a glycosyl sequence similar to RG-II from terrestrial plants. Nevertheless, species-dependent variations in the extent of methyl-etherification of RG-II sidechain A and arabinosylation of sidechain B are discernible. Immunocytochemical studies revealed that pectin methyl-esterification is higher in developing daughter frond walls than in mother frond walls, indicating that methyl-esterification is associated with expanding cells. Our data support the notion that a functional cell wall requires conservation of RG-II structure and cross-linking but can accommodate structural changes in other pectins. the Lemnoideae provide a model system to study the mechanisms by which wall structure and composition has changed in closely related plants with similar growth habits.Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences of the United States Department of EnergyUnited States Department of Energy (DOE) [DE-FG02-12ER16324, DE-FG02-12ER16326, DE-FG02-96ER20220]; National Science FoundationNational Science Foundation (NSF) [ISO-0923992]The authors acknowledge the Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences of the United States Department of Energy through Grants DE-FG02-12ER16324 and DE-FG02-12ER16326 (to M.A.O and M.J.P.) for funding the structural studies of Lemnoideae cell walls and DE-FG02-96ER20220 for analytical instrumentation support. the generation and use of plant cell wall glycan-directed antibodies were supported by National Science Foundation Plant Genome Grant ISO-0923992

The alpha-Aurora Kinases Function in Vascular Development in Arabidopsis

Wang, Huanzhong/0000-0002-9004-3420WOS: 000459633500018PubMed: 30329113The Aurora kinases are serine/threonine kinases with conserved functions in mitotic cell division in eukaryotes. in Arabidopsis, Aurora kinases play important roles in primary meristem maintenance, but their functions in vascular development are still elusive. We report a dominant xdi-d mutant showing the xylem development inhibition (XDI) phenotype. Gene identification and transgenic overexpression experiments indicated that the activation of the Arabidopsis Aurora 2 (AtAUR2) gene is responsible for the XDI phenotype. in contrast, the aur1-2 aur2-2 double mutant plants showed enhanced differentiation of phloem and xylem cells, indicating that the Aurora kinases negatively affect xylem differentiation. the transcript levels of key regulatory genes in vascular cell differentiation, i.e. ALTERED PHLOEM DEVELOPMENT (APL), VASCULAR-RELATED NAC-DOMAIN 6 (VND6) and VND7, were higher in the aur1-2 aur2-2 double mutant and lower in xdi-d mutants compared with the wild-type plants, further supporting the functions of alpha-Aurora kinases in vascular development. Gene mutagenesis and transgenic studies showed that protein phosphorylation and substrate binding, but not protein dimerization and ubiquitination, are critical for the biological function of AtAUR2. These results indicate that alpha-Aurora kinases play key roles in vascular cell differentiation in Arabidopsis.National Science FoundationNational Science Foundation (NSF) [IOS-1453048]; USDA National Institute of Food and AgricultureUnited States Department of Agriculture (USDA) [1016700]; University of Connecticut [UConn Research Excellence Program (REP)]This work was supported by the National Science Foundation [IOS-1453048]; USDA National Institute of Food and Agriculture [Hatch project accession number 1016700]; and by the University of Connecticut [UConn Research Excellence Program (REP) to H.W.]

Optimisation of design parameters of the finned tube heat exchanger by numerical simulations and artificial neural networks for the condensing wall hang boilers

This research investigates the use of computational fluid dynamics (CFD) and artificial neural networks (ANNs) to be optimized the design of finned tube heat exchangers for use in condensing wall-mounted boilers (WHBcs). Fin height, thickness, and distance are selected as the input design parameters, and the internal volume of the heat engine is modelled using the CFDHT (CFD and heat transfer) method. Different ANN structures are trained and tested on the resulting data to identify the optimal training process. The trained ANN is then used to predict various output parameters, including total heat transfer on the inner surface of the tube, maximum temperature on the fins, total heat transfer per unit volume of the heat exchanger, and pressure drop between the inlet and outlet of the internal volume. The optimal design scenarios are evaluated based on design criteria, and the ANN is found to have good statistical performance, with an average accuracy of 1.00018 and a maximum relative error of 9.16%. The ANN is able to accurately estimate the optimal design case.</p

Optimisation of design parameters of the finned tube heat exchanger by numerical simulations and artificial neural networks for the condensing wall hang boilers

This research investigates the use of computational fluid dynamics (CFD) and artificial neural networks (ANNs) to be optimized the design of finned tube heat exchangers for use in condensing wall-mounted boilers (WHBcs). Fin height, thickness, and distance are selected as the input design parameters, and the internal volume of the heat engine is modelled using the CFDHT (CFD and heat transfer) method. Different ANN structures are trained and tested on the resulting data to identify the optimal training process. The trained ANN is then used to predict various output parameters, including total heat transfer on the inner surface of the tube, maximum temperature on the fins, total heat transfer per unit volume of the heat exchanger, and pressure drop between the inlet and outlet of the internal volume. The optimal design scenarios are evaluated based on design criteria, and the ANN is found to have good statistical performance, with an average accuracy of 1.00018 and a maximum relative error of 9.16%. The ANN is able to accurately estimate the optimal design case.</p