Examination of the structural polymers orientation in the cell wall of hardwood (Acer platanoides L.), softwood (Picea omorika (Pančić) Purkyně) and liana plant (Dioscorea balcanica Košanin)

Ćelijski zid vlakana drveta može se smatrati kao nano-kompozit, u kojem su celuloza, lignin i hemiceluloze kompleksno povezani. Organizacija i svojstva polimera drveta u velikoj meri određuju svojstva vlakana i drveta, pa je i razumevanje interakcija između ovih polimera ključ za genetski razvoj poboljšanog drveta i kvaliteta vlakana...A wood fibre cell wall can be considered as a nano-composite, in which cellulose, lignin and hemicelluloses (xylan and glucomannan) are interconnected in an intricate manner. Structural organisation of the cell wall and related polymers is important for both mechanical properties of the plants and chemical reactions occurring in the wall space, especially in the response to stress..

ORIENTATION OF CELL WALL POLYMERS IN THE Arabidopsis thaliana STEM

Mechanical and physical propreties of plant fibres are dependent on the orientation of constituent polymers (cellulose, hemicellulose, lignin). Fourier transform infrared (FTIR) microscopy was used to examine the orientation of the main plant polymers in transversal and longitudinal direction of the isolated cell wall of the Arabidopsis thaliana stem. The polarised FTIR measurements indicated that xylan and glucomannan have parallel orientation with regard to the orientation of cellulose, as well as lignin

Serbian spruce, endemicity and advantages

Picea omorika (Pančić) Purkynĕ is Balkan endemic coniferous species and Tertiary relict of the European flora. Its natural habitat is fragmented and reduced to the middle and upper courses of the Drina River, in Western Serbia and Eastern Bosnia and Herzegovina. This region represents species long-term, cryptic and last refugium. The current limited natural range of Serbian spruce is mainly the result of the species poor competing ability. It retreats to areas less inhabitable by its competitors, predominantly Picea abies and Fagus orientalis. It inhabits open habitats, comprising cliffs and forest clearings, characterized by strong northerlywind, snow and rockfalls. Since the middle of the 19th century, its natural range declines continuously. Planting Serbian spruce outside its natural range has a long tradition, either as an ornamental tree species, or for afforestation, throughout Central and Northern Europe. Despite its endemism, P. omorika is considered as one of the most adaptable spruces. Wood properties are determined by cell arrangement, size and shape, and cell wall structure and thickness. Conifers, as a response to mechanical stress, such as wind and stem lean, form reaction wood called compression wood (CW). Its formation occurs on the lower side of the leaning stem, resulting in eccentric growth. Wood opposite to the CW in the same growth ring is termed opposite wood (OW), while wood from growth rings that do not contain any CW is termed normal wood (NW). CW is characterized by reduced tracheid length, rounder cell cross-sectional profile, presence of intercellular spaces, absence of the S3 cell wall layer and presence of helical cavities in S2 layer. Higher lignification, as one of the main characteristics of CW, is associated with changed lignin composition, increased amounts of phydroxyphenyl monomers and increased condensation of monomer units in the polymer. Consequently, CW contains less cellulose, with greatly increased amounts of galactan, and slightly lower amounts of mannan and xylan, and with higher angle of cellulose microfibrils in the S2 layer of the cell wall, compared to NW. CW occurs in a range of gradations from near NW to severe CW (SCW), mild CW (MCW) forming a continuum between NW and SCW. The degree of development of particular features of CW does not necessarily change in parallel to each other, so the severity of a given tracheid is represented as a function of the degrees of development of individual features, mainly lignification, helical cavities and cell wall thickness. Visual detection of compression wood severity, more precisely the determination of MCW, is difficult. As the severity of CW affects mechanical and chemical properties of wood in forest products industry it is desirable to be able to measure CW severity. We developed different morphometric and non-morphometric methods for distinguishing wood samples on a compression severity scale. They are based on tracheid double wall thickness, cellulose microfibrils order (distribution and alignment of cellulose microfibrils), or variation in lignin structure. We used confocal fluorescence microscopy and spectroscopy, and fluorescence-detected linear dichroism (FDLD) microscopy, combined with development of new algorithms and statistical analysis. We tested our methods on stem samples of P. omorika juvenile trees exposed to long term static bending. P. omorika belongs to slow-growing conifer species in which CW typically occurs in a severe form, while juvenile conifer wood is characterized by randomly distributed MCW, NW often being absent. These are the features that suggest P. omorika juvenile wood a good choice of samples for evaluation of the precision of methods suggested for estimation of compression wood severity. Our methods for distinguishing wood samples on a compression severity scale provide a fine gradation of juvenile P. omorika wood samples from NW to the severest form of CW, compression severity scales being partially different. The presented results qualify our methods for use in estimation of compression wood severity in forest products industries, individually or in combination, and confirm juvenile P. omorika stem samples as a good choice of samples for evaluation of the precision of methods suggested for compression wood severity estimation

Serbian spruce (Picea omorika (Pančić) Purkyné) - endemicity and advantages

Conifers, as a response to mechanical stress, such as wind and stem lean, form reaction wood called compression wood (CW). CW occurs in a range of gradations from near normal wood (NW) to severe CW (SCW). As the severity of CW affects the mechanical and chemical properties of wood, and as CW has limited value in the forest products industry, it is desirable to be able to measure CW severity. Picea omorika belong to slow-growing conifer species in which CW typically occurs in a severe form. We developed different morphometric and non-morphometric methods for estimation of CW severity tested on wood samples of P. omorika juvenile trees exposed to long term static bending. This specific review is aimed at presenting P. omorika as one of the most adaptable spruces, and as a good model for testing of methods for estimation of compression wood severity. First, we summarize main knowledge about P. omorika, features of CW, and methods for assessment of wood quality. Then, we present breifly our recently published methods for estimation of compression wood severity tested on P. omorika juvenile wood samples.Konifere kao odgovor na mehanički stres (vetar, savijanje) formiraju reakciono drvo koje se naziva kompresiono drvo (CW). CW se javlja u nizu gradacija od skoro normalnog drveta (NW) do jako izraženog CW (SCW). S obzirom da stepen izraženosti osobina CW ima značajan uticaj na mehaničke i hemijske osobine drveta i da CW ima ograničenu vrednost za drvnu industriju, poželjno je moći odrediti stepen izraženosti osobina CW u uzorku. Picea omorika spada u sporo rastuće četinarske vrste kod kojih se CW tipočno javlja u jako izraženoj formi. Mi smo razvili nekoliko morfometrijskih i ne-morfometrijskih metoda za procenu izraženosti osobina CW u uzorku, testiranih na uzorcima drveta juvenilnih stabala P. omorika koja su bila izložena dugotajnom statičkom savijanju. Ovaj revijski rad ima za cilj da predstavi Pančićevu omoriku kao jednu od najadaptabilnijih smrča i kao dobar model za testiranje metoda za procenu izraženosti osobina CW u uzorku. U prvom delu sumiramo znanja o Pančićevoj omorici, osobinama CW i metodama za procenu kvaliteta drveta, a u drugom ukratko predstavljamo naše nedavno objavljene metode za za procenu izraženosti osobina CW u uzorku, testirane na uzorcima drveta juvenilnih stabala P. omorika

The use of fluorescence microscopy for classification of pollen grains

In this pilot research, we showed that pollen autofluorescence varied between the pollen of the different botanical species. Our findings suggest that classification of pollen grains may be obtained based on their fluorescence images

Structural characterisation and orientation of cell wall polymers in Arabidopsis thaliana stem

Plant cell walls are composed of a framework of cellulose microfibrils that are interconnected with heteropolysaccharides (lignin, hemicelluloses) in a specific manner. Plant cell walls form a large part of the plant body and define its characteristics. Structural organisation of the cell wall and related polymers is important for both mechanical properties of plants and chemical reactions occurring in the wall space, especially in the response to stress.By using imaging FTIR microscopy, run in transmission mode and at different polarisation modes (from 0° to 90°), it is possible to follow the chemical variability and the orientation of cell wall polymers (cellulose, hemicelluloses and lignin) of the Arabidopsis thaliana stem. The polarised FTIR measurements indicated that both xylan and lignin have parallel orientation with regard to the orientation of cellulose. It is believed that this structuring of lignin in the S2 layer of the cell wall might be a result of the spatial constraints within the cell wall, occuring due to the previous deposition of cellulose/hemicellulose in a strongly oriented assembly

Mehanički stres i drvenaste biljke

Целулоза, лигнин и хемицелулозе су главне компоненте ћелијског зида које су комплексно повезане. Начин на који су ови полимери дрвета спрегнути међусобно и њихове особине утичу на својства влакана и дрвета, па је разумевање интеракција између ових полимера важно за разумевање механичких својстава дрвета, као одговора биљке на стрес, али такође и као могућу употребу дрвета као извора нових биоматеријала. Ћелијски зид се састоји од примарног зида (P), спољашњег секундарног зида (S1), средњег секундарног зида (S2) и унутрашњег секундарног зида (S3). У ћелијском зиду су доминантне особине S2 слоја јер он чини 80% укупне масе ћелијског зида. Целулоза је релативно паралелно оријентисана у односу на осу ћелијског зида што даје механичку снагу ћелијском зиду.1,2 Главна разлика између хемицелулозе тврдог и меког дрвета је у садржају ксилана и глукоманана. Постоје разлике и у лигнинским мономерним прекурсорима у ћелијским зидовима ове две врсте дрвета. Лигнин у меком дрвету садржи јединице гвајакола, док лигнин у тврдом дрвету садржи и гвајакол и сирингил мономере.3 Већина истраживања која се односе на оријентацију су фокусирана само на оријентацију целулозних микрофибрила. Међутим, организација преосталих полимера дрвета је од значаја код разумевања формирања ћелијског зида током раста. Анизотропију односно структурну уређеност ћелијског зида проучавали смо применом диференцијално поларизоване флуоресцентне микроскопије, као и применом ФТИР микро-спектроскопије

STRUCTURAL CHARACTERISATION AND ORIENTATION OF CELL WALL POLYMERS IN MAIZE LEAVES

Cell wall can be considered as a nano-composite in which cellulose, lignin and hemicelluloses are interconnected in a specific manner. Mechanical and physical propreties of plant fibres are dependent on the orientation of constituent polymers (cellulose, hemicellulose, lignin). Fourier transform infrared (FTIR) microscopy was used to examine the orientation of the main plant polymers in transversal and longitudinal direction of the isolated cell wall of the maize leaves. Polarised FTIR measurements indicated an anisotropy, i.e. orientation of the cellulose microfibrils that was more or less parallel to the longitudinal axis of the cell wall. Xylan has parallel orientation with regard to the orientation of cellulose, as well as lignin

FTIR analysis of xylem vessel cell walls in twining stem of Dioscorea balcanica

Using stem cross sections of Dioscorea balcanica, as a model, we detected changes in anatomy and structural organization of xylem vessel cell walls (CWs) linked to stem twining in liana plants. UV microscopy, scanning electron microscopy and Fourier transform infrared (FTIR) microspectrometry were used. Different microfibrils orientation in vessel CWs of twisted compared to straight internodes, revealed by histological examination, coincide with the lower lignin content, the lower amount of xylan and cellulose, and the higher amount of xyloglucan, showed by FTIR. Xylem vessels resist high mechanical strain developed in twisted internodes by decreased CW rigidity (lower lignin content) and extensibility (higher xyloglucan content), and increased elasticity (lower xylan content)

Imaging FTIR microscopy – technique for rapid screening of plant cell walls

It has been shown that xylan is oriented in parallel to the cellulose and more or less parallel to the axis of a cell wall, in isolated CW fragments from maize leaves. There was also a clear indication of lignin orientation parallel to the longitudinal CW axis. This means that all of these components show strong anisotropic behaviour and organisation