Comparison of macromolecular interactions in the cell walls of hardwood, softwood and maize by fluorescence and FTIR spectroscopy, differential polarization laser scanning microscopy and X-ray diffraction

Interactions between macromolecules in the cell walls of different plant origin were compared, namely spruce wood (Picea omorika (PaniA double dagger) PurkiAe) as an example of softwood, maple wood (Acer platanoides L.) as a hardwood and maize stems (Zea mays L.) as a herbaceous plant from the grass family and widely used agricultural plant. Interactions of macromolecules in isolated cell walls from the three species were compared by using Fourier transform infrared spectroscopy, X-ray diffraction and fluorescence spectroscopy. Linear dichroism of the cell walls was observed by using differential polarization laser scanning microscope (DP-LSM), which provides information of macromolecular order. This method has not previously been used for comparison of the cell walls of various plant origins. It was shown that the maize cell walls have higher amount of hydrogen bonds that lead to more regular packing of cellulose molecules, simpler structure of lignin, and a higher crystallinity of the cell wall in relation to the walls of woody plants. DP-LSM and fluorescence spectroscopy results indicate that maize has simpler and more ordered structure than both woody species. The results of this work provide new data for comparison of the cell wall properties that may be important for selection of appropriate plant for possible applications as a source of biomass. This may be a contribution to the development of efficient deconstruction and separation technologies that enable release of sugar and aromatic compounds from the cell wall macromolecular structure

Parenchyma cell wall structure in twining stem of Dioscorea balcanica

Anatomical adaptation of liana plants includes structural changes in cell walls of different tissues: fibers, vessel elements and tracheids. However, the contribution of parenchyma cells to stem twining in liana plants is mostly unknown. The aim of this investigation is to determine changes in stem parenchyma cell walls that are correlated with the twinning process in liana plants. Parenchyma cell wall structure was studied on the stem cross sections of straight and twisted internodes of monocotyledonous liana Dioscorea balcanica, by different microscopy techniques: light microscopy, scanning electron microscopy, fluorescence detected linear dichroism microscopy and Fourier transform infrared microspectrometry. In addition, chemical analysis of the entire stem internodes was performed using photometric and chromatographic methods. Parenchyma cell walls of twisted D. balcanica internodes are characterized by: lower amounts of cellulose (obtained by FTIR microspectrometry) with different cellulose microfibril orientation (shown by Scanning electron microscopy), but no changes in "cellulose fibril order" (obtained by Differential polarization laser scanning microscopy); lower amounts of xyloglucan, higher amounts of xylan, higher amounts of lignin with modified organization-less condensed lignin (obtained by FTIR microspectrometry). At the same time, chemical analysis of the entire internodes did not show significant differences in lignin content and cell wall bound phenols related to stem twining, except for the presence of diferulate cross-links exclusively in twisted internodes. Our results indicate that adaptations to mechanical strain in D. balcanica stems involve modifications in parenchyma cell wall structure and chemistry, which provide decreased stiffness, higher strength and increased elasticity of twisted internodes.Correction: [http://cer.ihtm.bg.ac.rs/handle/123456789/2480

Decomposition kinetic study, spectroscopic and pyrolytic analyses of Isoberlinia doka and Pinus ponderosa

Two woody species of different origins were subjected to Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis, and analytical pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). FlynnWall-Ozawa, a model-free technique, was adopted for the decomposition kinetic study of Isoberlinia doka (ID) and Pinus ponderosa (PP). FTIR spectroscopy was employed to determine the level of cellulose crystallinity in the samples under investigation using the total crystallinity and lateral order indices methods. The apparent activation energy appeared as a function of conversion with significant influence from biomass diversity. The apparent activation energy recorded values of 202 to 365 kJ mol−1 for ID and 205 to 583 kJ mol−1 for PP. Thus, biomass decomposition kinetics is better modeled as a multi-step reaction mechanism. The analytical Py-GC/MS showed the presence of acids, sugars, and phenolic compounds in significant proportions for the two biomass samples. There were marked distinctions in both the quantity and the individual compounds detected in the biomass samples that were investigated