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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 1M KOH extracts from eight phylogenetically diverse plant biomasses with or without AFEX™ pre-treatment. The 1M KOH 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 1 M KOH 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. 5, 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 6: Scatter plot analyses of the relative abundance of major non-cellulosic cell wall glycan epitopes in 1M KOH extracts from eight phylogenetically diverse plant biomasses with or without AFEX™ pre-treatment. The 1M KOH 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 1 M KOH 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. 5, 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: Extraction of both native and pre-treated biomass with 1M KOH (third extraction step) yielded dramatically less material for the two gymnosperm biomasses compared with the other samples (Fig. 5, bar graphs). The most significant difference observed in the glycome profiles of the 1M KOH extracts was the enhanced extractability of xyloglucan epitopes from all pre-treated biomass samples, irrespective of their phylogenetic origin. This was particularly true for the medium and severely pre-treated samples as observed on the heat maps (Fig. 5; white dotted blocks), as well as in the scatter plot analyses of the medium severity AFEX™ pre-treatment data (Fig. 6). For loblolly pine, enhanced extractability of fewer xyloglucan epitopes after AFEX™ pre-treatment was observed compared with the other biomass samples. In general, AFEX™ pre-treatment appeared to have little effect on glycome profiles of the base-extractable xylan and pectin/arabinogalactan epitopes when comparing pre-treated with untreated biomass samples. This is most easily seen in the scatter plots (Fig. 6), where most of the points fall along or close to the diagonal x=y line. Interestingly, AFEX™-pre-treated corn stover showed lower abundance of both xylan and pectin/arabinogalactan epitopes versus untreated biomass, probably due to the fact that a significant fraction of these matrix polymers had been removed from the pre-treated samples in the oxalate and carbonate extractions.


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 1M KOH extracts from eight phylogenetically diverse plant biomasses with or without AFEX™ pre-treatment. The 1M KOH 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 1 M KOH 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. 5, 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 6: Scatter plot analyses of the relative abundance of major non-cellulosic cell wall glycan epitopes in 1M KOH extracts from eight phylogenetically diverse plant biomasses with or without AFEX™ pre-treatment. The 1M KOH 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 1 M KOH 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. 5, 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: Extraction of both native and pre-treated biomass with 1M KOH (third extraction step) yielded dramatically less material for the two gymnosperm biomasses compared with the other samples (Fig. 5, bar graphs). The most significant difference observed in the glycome profiles of the 1M KOH extracts was the enhanced extractability of xyloglucan epitopes from all pre-treated biomass samples, irrespective of their phylogenetic origin. This was particularly true for the medium and severely pre-treated samples as observed on the heat maps (Fig. 5; white dotted blocks), as well as in the scatter plot analyses of the medium severity AFEX™ pre-treatment data (Fig. 6). For loblolly pine, enhanced extractability of fewer xyloglucan epitopes after AFEX™ pre-treatment was observed compared with the other biomass samples. In general, AFEX™ pre-treatment appeared to have little effect on glycome profiles of the base-extractable xylan and pectin/arabinogalactan epitopes when comparing pre-treated with untreated biomass samples. This is most easily seen in the scatter plots (Fig. 6), where most of the points fall along or close to the diagonal x=y line. Interestingly, AFEX™-pre-treated corn stover showed lower abundance of both xylan and pectin/arabinogalactan epitopes versus untreated biomass, probably due to the fact that a significant fraction of these matrix polymers had been removed from the pre-treated samples in the oxalate and carbonate extractions.

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.