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Insights into plant cell wall structure, architecture, and integrity using glycome profiling of native and AFEXTM-pre-treated biomass.

Pattathil S, Hahn MG, Dale BE, Chundawat SP - J. Exp. Bot. (2015)

Bottom Line: For most biomass types analysed, such loosening was also evident for other major non-cellulosic components including subclasses of pectin and xyloglucan epitopes.The studies also demonstrate that AFEX™ pre-treatment significantly reduced cell wall recalcitrance among diverse phylogenies (except softwoods) by inducing structural modifications to polysaccharides that were not detectable by conventional gross composition analyses.It was found that monitoring changes in cell wall glycan compositions and their relative extractability for untreated and pre-treated plant biomass can provide an improved understanding of variations in structure and composition of plant cell walls and delineate the role(s) of matrix polysaccharides in cell wall recalcitrance.

View Article: PubMed Central - PubMed

Affiliation: Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA siva@ccrc.uga.edu shishir.chundawat@rutgers.edu.

No MeSH data available.


Scatter plot analyses of the relative abundance of major non-cellulosic cell wall glycan epitopes in carbonate extracts from eight phylogenetically diverse plant biomasses with or without AFEX™ pre-treatment. Carbonate extracts were prepared from cell walls isolated from diverse classes of plant biomass as explained in the Materials and Methods. The extracts were subsequently screened by ELISA using a comprehensive suite of cell wall glycan-directed mAbs. Comparisons of the relative abundances of epitopes characteristic of three cell wall polysaccharide classes, xyloglucans (blue dots), xylans (red dots), and pectin/arabinogalactans (green dots), in the carbonate extracts before and after medium severity AFEX™ pre-treatment of diverse plant biomass samples (see Fig. 2 for more details). Data are re-plotted from Fig. 3, but are normalized to represent mAb binding strength per mass of original cell wall. The red dashed lines denote the expected position if the abundance of these glycan epitopes was unchanged after AFEX™ pre-treatment. Data points above and below the dashed lines represent increased or decreased glycan epitope abundance, respectively, after AFEX™ pre-treatment. Note that the y-axis scales are different for individual plots to permit visualization of trends and magnitudes of normalized epitope abundances.
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Figure 4: Scatter plot analyses of the relative abundance of major non-cellulosic cell wall glycan epitopes in carbonate extracts from eight phylogenetically diverse plant biomasses with or without AFEX™ pre-treatment. Carbonate extracts were prepared from cell walls isolated from diverse classes of plant biomass as explained in the Materials and Methods. The extracts were subsequently screened by ELISA using a comprehensive suite of cell wall glycan-directed mAbs. Comparisons of the relative abundances of epitopes characteristic of three cell wall polysaccharide classes, xyloglucans (blue dots), xylans (red dots), and pectin/arabinogalactans (green dots), in the carbonate extracts before and after medium severity AFEX™ pre-treatment of diverse plant biomass samples (see Fig. 2 for more details). Data are re-plotted from Fig. 3, but are normalized to represent mAb binding strength per mass of original cell wall. The red dashed lines denote the expected position if the abundance of these glycan epitopes was unchanged after AFEX™ pre-treatment. Data points above and below the dashed lines represent increased or decreased glycan epitope abundance, respectively, after AFEX™ pre-treatment. Note that the y-axis scales are different for individual plots to permit visualization of trends and magnitudes of normalized epitope abundances.

Mentions: The trends observed in heat maps of the oxalate extracts were continued in the heat maps of the carbonate extracts (second extraction stage); that is, the carbonate extracts exhibited an enhanced abundance of various xylan epitopes (Fig. 3, yellow dotted blocks) after AFEX™ pre-treatment compared with untreated biomass. Again, scatter plot analyses substantiated these results, with increased abundance of xylan epitopes in all pre-treated biomass samples (Fig. 4). Closer inspection of both oxalate and carbonate heat maps revealed that some xylan epitope groups [e.g. xylan-6 mAbs, which recognize unsubstituted homoxylan epitope structures (Schmidt et al., 2015)] are more recalcitrant and require harsher AFEX™ pre-treatment conditions to facilitate their removal compared with other xylan epitope groups (e.g. xylan-4, -5, and -7). AFEX™ pre-treatment also resulted in enhanced extractability of xyloglucan epitopes for all of the biomass samples with the exception of golden rod, a herbaceous dicot, and both gymnosperms. The abundance of pectin and arabinogalactan epitopes in carbonate extracts from pre-treated biomass as depicted by scatter plots showed little enhanced extractability of these epitopes after AFEX™ pre-treatment for all biomass samples except for switchgrass and alfalfa, which showed increased abundance of almost all of these epitopes (Fig. 4).


Insights into plant cell wall structure, architecture, and integrity using glycome profiling of native and AFEXTM-pre-treated biomass.

Pattathil S, Hahn MG, Dale BE, Chundawat SP - J. Exp. Bot. (2015)

Scatter plot analyses of the relative abundance of major non-cellulosic cell wall glycan epitopes in carbonate extracts from eight phylogenetically diverse plant biomasses with or without AFEX™ pre-treatment. Carbonate extracts were prepared from cell walls isolated from diverse classes of plant biomass as explained in the Materials and Methods. The extracts were subsequently screened by ELISA using a comprehensive suite of cell wall glycan-directed mAbs. Comparisons of the relative abundances of epitopes characteristic of three cell wall polysaccharide classes, xyloglucans (blue dots), xylans (red dots), and pectin/arabinogalactans (green dots), in the carbonate extracts before and after medium severity AFEX™ pre-treatment of diverse plant biomass samples (see Fig. 2 for more details). Data are re-plotted from Fig. 3, but are normalized to represent mAb binding strength per mass of original cell wall. The red dashed lines denote the expected position if the abundance of these glycan epitopes was unchanged after AFEX™ pre-treatment. Data points above and below the dashed lines represent increased or decreased glycan epitope abundance, respectively, after AFEX™ pre-treatment. Note that the y-axis scales are different for individual plots to permit visualization of trends and magnitudes of normalized epitope abundances.
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Related In: Results  -  Collection

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Figure 4: Scatter plot analyses of the relative abundance of major non-cellulosic cell wall glycan epitopes in carbonate extracts from eight phylogenetically diverse plant biomasses with or without AFEX™ pre-treatment. Carbonate extracts were prepared from cell walls isolated from diverse classes of plant biomass as explained in the Materials and Methods. The extracts were subsequently screened by ELISA using a comprehensive suite of cell wall glycan-directed mAbs. Comparisons of the relative abundances of epitopes characteristic of three cell wall polysaccharide classes, xyloglucans (blue dots), xylans (red dots), and pectin/arabinogalactans (green dots), in the carbonate extracts before and after medium severity AFEX™ pre-treatment of diverse plant biomass samples (see Fig. 2 for more details). Data are re-plotted from Fig. 3, but are normalized to represent mAb binding strength per mass of original cell wall. The red dashed lines denote the expected position if the abundance of these glycan epitopes was unchanged after AFEX™ pre-treatment. Data points above and below the dashed lines represent increased or decreased glycan epitope abundance, respectively, after AFEX™ pre-treatment. Note that the y-axis scales are different for individual plots to permit visualization of trends and magnitudes of normalized epitope abundances.
Mentions: The trends observed in heat maps of the oxalate extracts were continued in the heat maps of the carbonate extracts (second extraction stage); that is, the carbonate extracts exhibited an enhanced abundance of various xylan epitopes (Fig. 3, yellow dotted blocks) after AFEX™ pre-treatment compared with untreated biomass. Again, scatter plot analyses substantiated these results, with increased abundance of xylan epitopes in all pre-treated biomass samples (Fig. 4). Closer inspection of both oxalate and carbonate heat maps revealed that some xylan epitope groups [e.g. xylan-6 mAbs, which recognize unsubstituted homoxylan epitope structures (Schmidt et al., 2015)] are more recalcitrant and require harsher AFEX™ pre-treatment conditions to facilitate their removal compared with other xylan epitope groups (e.g. xylan-4, -5, and -7). AFEX™ pre-treatment also resulted in enhanced extractability of xyloglucan epitopes for all of the biomass samples with the exception of golden rod, a herbaceous dicot, and both gymnosperms. The abundance of pectin and arabinogalactan epitopes in carbonate extracts from pre-treated biomass as depicted by scatter plots showed little enhanced extractability of these epitopes after AFEX™ pre-treatment for all biomass samples except for switchgrass and alfalfa, which showed increased abundance of almost all of these epitopes (Fig. 4).

Bottom Line: For most biomass types analysed, such loosening was also evident for other major non-cellulosic components including subclasses of pectin and xyloglucan epitopes.The studies also demonstrate that AFEX™ pre-treatment significantly reduced cell wall recalcitrance among diverse phylogenies (except softwoods) by inducing structural modifications to polysaccharides that were not detectable by conventional gross composition analyses.It was found that monitoring changes in cell wall glycan compositions and their relative extractability for untreated and pre-treated plant biomass can provide an improved understanding of variations in structure and composition of plant cell walls and delineate the role(s) of matrix polysaccharides in cell wall recalcitrance.

View Article: PubMed Central - PubMed

Affiliation: Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA siva@ccrc.uga.edu shishir.chundawat@rutgers.edu.

No MeSH data available.