Differential Polarization Imaging of Plant Cells. Mapping the Anisotropy of Cell Walls and Chloroplasts

Modern light microscopy imaging techniques have substantially advanced our knowledge about the ultrastructure of plant cells and their organelles. Laser-scanning microscopy and digital light microscopy imaging techniques, in general-in addition to their high sensitivity, fast data acquisition, and great versatility of 2D-4D image analyses-also opened the technical possibilities to combine microscopy imaging with spectroscopic measurements. In this review, we focus our attention on differential polarization (DP) imaging techniques and on their applications on plant cell walls and chloroplasts, and show how these techniques provided unique and quantitative information on the anisotropic molecular organization of plant cell constituents: (i) We briefly describe how laser-scanning microscopes (LSMs) and the enhanced-resolution Re-scan Confocal Microscope (RCM of Confocal.nl Ltd. Amsterdam, Netherlands) can be equipped with DP attachments-making them capable of measuring different polarization spectroscopy parameters, parallel with the 'conventional' intensity imaging. (ii) We show examples of different faces of the strong anisotropic molecular organization of chloroplast thylakoid membranes. (iii) We illustrate the use of DP imaging of cell walls from a variety of wood samples and demonstrate the use of quantitative analysis. (iv) Finally, we outline the perspectives of further technical developments of micro-spectropolarimetry imaging and its use in plant cell studies

COMPARISON OF CELL WALL STRUCTURE OF DIFFERENT WESTERN BALKAN PLANT SPECIES AS A SOURCE FOR BIOFUELS

Understanding of composition and connections between the building macromolecules of plant biomass, such as cellulose, hemicellulose and lignin, is main key for their better utilization in biofuels industry. We compared four different plant species which are abundant in the region of the Western Balkans. We investigated the structure of the cell walls, as the main constituent of plant biomass, isolated from branches of softwood (Picea omorika (Pancic) Purkine), hardwood (Acer platanoides L.), maize stem (Zea mays L.) as examples of crop species, and Paulownia tomentosa tree as a fast-growing species with a huge biomass yield. For our investigation, we combined Fluorescence-detected linear dichroism (FDLD) method and X-ray Diffraction. We obtained data for anisotropy and crystallography which are a base for prediction of the best and appropriate plant species for easy deconstruction of its biomass. Our results show that Acer branch as a hardwood shows the highest anisotropy and the lowest crystallinity compared to the other species while Picea Omorika needles show opposite results as the lowest anisotropy and the higher crystallinity. The results for maize show that the stems are easier for utilization than leaves. The isolated cell walls from leaves of Paulownia tomentosa show similar results and good correlation between anisotropy and crystallinity, thus we can conclude that this plant is easy to use in biofuel industries

Differential Polarization Laser Scanning Microscopy (DP-LSM) -Technique for Rapid Screening of Cell Walls of Different Plant Species

DP-LS microscopy is a useful and easily applicable technique for rapid screening of cell wall structural order, by mapping the linear dichroism of cellulose fibrils. It allows screening and quantification of the alignment of cellulose fibrils, relative to one another, in cell walls. The goal was to provide new information about structural characteristics of the isolated cell walls among species which may be a basis for their possible applications, such as biofuel and biomaterial industry, but also to understand what plant response to stress is. The DP-LSM method is shown to be a simple and rapid way to check the structural complexity in the cell wall through cellulose labeling

Fabrication, characterization and photoelectrochemical behavior of Fe2TiO5 screen printed thick films

Pseudobrookite paste was composed of a mixture of starting nanopowders of hematite (α-Fe2O3) and anatase (TiO2) in the molar ratio 1:1.5, organic vehicle and glass frit. The paste was screen printed on on fluorine-doped tin oxide (FTO) glass substrate using screen printing technology. Structural, morphological and optical studies have been carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and transmission electron microscopy (TEM). The photo-electrochemical performance of Fe2TiO5 screen printed thick film was examined under xenon lamp illumination in 1 M NaOH electrolyte

Modifications in parenchyma cell wall structure related to stem twining in monocotyledonous liana Dioscorea balcanica Košanin

Anatomical adaptation of liana plants includes structural changes in cell walls of different tissues: fibers, vessel elements and tracheids. The contribution of parenchyma cells to stem twining is mostly unknown. Plants control the orientation and alignment of cellulose fibrils during the deposition in the cell walls with high precision, creating required anisotropy of the cell wall. Our aim was to determine possible changes in cellulose fibrils orientation and structural order in stem parenchyma cell walls related to stem twinning in liana plants. We applied different microscopy techniques: light microscopy, scanning electron microscopy and differential polarization laser scanning microscopy (DP-LSM) for fluorescence detected linear dichroism imaging (FDLD), on stem cross sections of straight and twisted internodes of monocotyledonous liana Dioscorea balcanica. Histochemical analysis showed no difference in parenchyma cell wall structure between straight and twisted internodes. Also, no difference in ‘‘cellulose fiber order’’ in parenchyma cell walls related to stem twining was found by FDLD microscopy. However, SEM micrographs suggested the difference in cellulose microfibril orientation in secondary cell walls of parenchyma cells related to stem twining. Our results indicate that adaptations to stem twining in liana plants involve modifications in cellulose microfibril orientation in parenchyma cell walls. Although the orientation of cellulose microfibrils dictates, among other properties, cell shape, living stem parenchyma cells in D. balcanica retain their shape regardless of stem twining, which is possibly enabled by retaining ‘‘cellulose fibril order’’

Fluorescence-Detected Linear Dichroism of Wood Cell Walls in Juvenile Serbian Spruce: Estimation of Compression Wood Severity.

Fluorescence-detected linear dichroism (FDLD) microscopy provides observation of structural order in a microscopic sample and its expression in numerical terms, enabling both quantitative and qualitative comparison among different samples. We applied FDLD microscopy to compare the distribution and alignment of cellulose fibrils in cell walls of compression wood (CW) and normal wood (NW) on stem cross-sections of juvenile Picea omorika trees. Our data indicate a decrease in cellulose fibril order in CW compared with NW. Radial and tangential walls differ considerably in both NW and CW. In radial walls, cellulose fibril order shows a gradual decrease from NW to severe CW, in line with the increase in CW severity. This indicates that FDLD analysis of cellulose fibril order in radial cell walls is a valuable method for estimation of CW severity

Correction to: Parenchyma cell wall structure in twining stem of Dioscorea balcanica (vol 24, pg 4653, 2017)

In the original publication of the article, one of the project numbers was omitted in the Acknowledgments. The correct version is provided below.Original publication: [http://cer.ihtm.bg.ac.rs/handle/123456789/2090

CELLULOSE ORIENTATION AND PURITY ASSESSMENT AFTER TWO DIFFERENT PROCEDURES OF CELL WALL ISOLATION FROM MAIZE STEMS. A COMBINED MICROSCOPIC FLUORESCENCE DETECTED LINEAR DICHROISM AND IMAGE ANALYSIS STUDY

The effects on cellulose orientation and purity of two different methods for cell wall isolation from maize stems were investigated by using fluorescence-detected linear dichroism (FDLD) microscopy technique. Image analysis has shown that treatment with sulfuric acid have provided better results than previously applied method for cell wall isolation including enzymatic treatment