Populus x euramericana tension wood as a model for selection of microscopic methods for rapid screening of cell wall structure in the analysis of plant stem properties

The plant cell wall (CW) is a cell compartment lying outside the plasma membrane forming a continuum throughout the plant body. The composition of CWs varies between plant species and cell types, while changes in CW constituents occur as a result of growth and developmental processes, or as a response to various environmental stimuli. In the herein study, we present a selection of microscopic methods for rapid, relatively simple, and low-cost visualization of CW structure/composition in tissues of stems in trees, shrubs, or herbs. Selected microscopic methods imply the use of unfixed, intact, both fresh and dried, plant tissues for the analysis, as well as free-hand or microtome sectioning. UV microscopy, phloroglucinol-HCl and toluidine blue O staining, SEM microscopy, and RAMAN microspectroscopy, separately or in combination, can provide valuable information in plant ecology, plant physiology studies, or for applications in agronomy and forest products industry. As a model, stem samples of juvenile Populus x euramericana trees exposed to severe long term static bending were selected: tension wood fibers (gelatinous fibers, specialized sclerenchyma cells) could be considered as representatives of CWs with the most complex structure, while the genus Populus is considered as a model woody Angiosperm

Anatomical injuries caused by Leipotrix dipsacivagus Petanovic & Rector on cut-leaf teasel, Dipsacus laciniatus L. (Dipsacaceae)

The present study highlights some conspicuous structural malformations of the native Eurasian plant Dipsacus laciniatus L. (Dipsacaceae) caused by infestation with a newly determined eriophyid mite, Leipothrix dip­sacivagus (Petanovic & Rector, 2007). The most striking structural changes, induced by mite feeding were evident in the stunted appearance of infested plants and conspicuous injuries to their leaf tissues. The significant damage it causes to D. laciniatus recommends the narrow host-range mite L. dipsacivagus as a potential agent for biological control of this plant, which is widespread everywhere in the lowlands of Europe and is listed as an invasive and noxious weed in the USA.U radu su opisane i kvantifikovane promene nalistovima Dipsacus laciniatus L. (Dipsacaceae) prouzrokovane infestiranjem eriofidnom grinjom Leipotrix dipsacivagus (Acari: Eriophyoidea). Infestirane biljke su nižeg stabla, manje veličine cvasti, "rđaste", kao i sa značajnim promenama u tkivima listova. Uočeni uticaj eriofidne grinje predstavlja mogućnost njene primene kao potencijalnog agensa biološke borbe protiv zeljaste korovske biljke D. laciniatus

The influence of concentration and temperature on the viscoelastic properties of tomato pomace dispersions

The influence of concentration and temperature on the rheological properties of tomato pomace dispersions obtained by rehydration of lyophilized and grinded tomato pomace was investigated in this paper. Examined systems comprised of different lyophilized tomato pomace concentrations (18.2, 16.7, 14.3, 12.5, 11.1, 10.0, and 9.1%) heat treated at two different temperatures (60 degrees C and 100 degrees C) during 30 min. According to microstructure analysis of the studied system, it could be simplified as the composite consisting of insoluble particles surrounded by the pectin network. The system behaves as viscoelastic solid (G' gt G '' at all angular velocities), and therefore the static modulus of elasticity, the effective modulus and the damping coefficient were determined by application of modified fractional Kelvin-Voigt model. The influence of particle concentration on the rheological properties of tomato pomace system is dominant in comparison to the content and composition of pectin solubilised in the serum. Concentrated tomato pomace dispersions are much stiffer (G' values an order of magnitude higher) than the composite systems. Heat treatment at higher temperature (100 degrees C) decreases the stiffness of the system by breaking of non-covalent bonds between dispersed tomato particles and surrounding pectin network. Storage modulus as a function of the tomato pomace lyophilizate concentration was considered within three regimes (regime 1 - concentration lt 11.1%; regime 2 - concentration 11.1%-16.7%; regime 3 - concentration gt 16.7%) that could be used as the base for formulation of tomato pomace-based products with different desirable consistencies, such as sauce, ketchup and marmalade