Phenolic Compounds and Cell Structure in Bilberry Leaves Affected by Emissions from a Zn–Pb Smelter

Abstract

Vaccinium myrtillus L. is a common shrub in the herbaceous layer of pine forests. In connection with resistance to pollution it has been widely used in the environmental monitoring based on heavy metal accumulations in the foliage. The present study investigates leaves of bilberry growing under influence of emissions from a Zn-Pb smelter. Determination of heavy metal levels by AAS revealed enhanced accumulations of Zn, Pb, Cd, and Fe, and the level of Zn fell into the toxic range compiled for plants of average sensitivity. To verify the significance of metal accumulations occurring in the studied plant, the concentrations of phenolics were quantified by measuring UV absorption of foliage extracts. Phenolics can be used as a potential biomarker of pollution because they participate in plant's response to accumulation of heavy metals, acting as antioxidants able to scavenge free radicals produced by metal ions. Leaves collected near the smelter contained significantly higher amounts of phenolics. Since these compounds are also responsible for ecological interactions, changes in their concentrations resulting from heavy metal accumulations might also influence other organisms in the ecosystem. To study the role of phenolics in heavy metal accumulations at the cellular level, a special fixation was applied for TEM, involving glutaraldehyde with caffeine, to precipitate phenolics in the cell. A histochemical reaction showed significantly higher electron-opacity, most probably deposits of phenolics, in cells of the leaves collected near the smelter. The subsequent degenerative changes in mesophyll of these leaves were characterized by increased contents of heterogeneous multivesicular structures, degeneration of chloroplasts, and disorganisation of membranes leading to death of the cell and necrosis.

Photosynthetic activity in relation to chlorophylls, carbohydrates, phenolics and growth of a hybrid Salix purpurea × triandra × viminalis 2 at various Zn concentrations

“…Accumulation of phenolics in leaves under metal exposure has also been observed in other studies, e.g. in Salix viminalis under Cu and Ni exposure Gąsecka et al 2012), in Camellia sinensis under Zn excess (Mukhopadhyay et al 2013) and in Vaccinium myrtillus near an Zn-Pb smelter (Białońska et al 2007). Among the phenolic acids, derivatives of t-cinnamic acids, especially chlorogenic acid (Niggeweg et al 2004), have strong antioxidant activity.…”

Assessing forest health via linking the geochemical properties of a soil profile with the biochemical parameters of vegetation

“…Limited work has been performed under field conditions exploring the effects of accumulated sediment/soilborne metals on biochemical processes in plant tissues and assessment of their suitability as potential biomarkers of metal stress (MacFarlane 2002;Bialonska et al 2007). Additionally, the contents of available macronutrients (Ca 2?…”

Yellow deposits formation in roots is a part of tobacco plant phenotype under sulfur deficiency

“…Such alteration, taken together with the eye-visible color difference, between the ethanol extracts analyzed in the experiments, point to the UV absorbing compounds (UVAC) as a reason of yellow color. The most abundant group of such molecules, reported as responsible for most of the changes of extract spectra in UV range are phenolic compounds (25,26). Noteworthy, phenolics (mostly the subgroup called flavonoids) are, besides chlorophylls, the main group of compounds that affect color of plant organs.…”