Adaptive Redox Reactions Promote Naturalization of Rare Orchid Epipactis atrorubens on Serpentine Dumps Post Asbestos Mining

Abstract

Epipactis atrorubens (Hoffm.) Besser. is a regionally rare orchid species with highly ornamental properties due to its very beautiful bright flowers, therefore it is of considerable interest as a horticultural plant for use in botanical gardens and greenhouses. The objective of the research was to assess metal accumulation and some pro- and antioxidant reactions in E. atrorubens, colonizing serpentine dumps post asbestos mining. Additionally, some physicochemical properties of substrates, microbiotic characteristics and water status were investigated in orchids growing on two serpentine dumps and in a natural forest habitat of the Middle Urals, Russia. The dump substrates were characterized by the strong stoniness and the high content of Mg, Ni, Cr and Co (by 1.8 times on average) compared to the natural habitat. In these sites, E. atrorubens was characterized by increased mycorrhization. In the rhizome and roots of E. atrorubens the concentrations of most metals studied were considerably higher (more than 4 times on average) than in the leaves. It was found that orchids colonizing serpentine dumps produced more lipid peroxidation products (by 1.4 times on average) in the leaves which was accompanied by the more active synthesis of such non-enzymatic antioxidants as ascorbate, free proline, soluble phenolic compounds (including flavonoids) and non-protein thiols. The study suggests that non-enzymatic antioxidants increased the adaptive potential of E. atrorubens and contributed to its naturalization on serpentine dumps post asbestos mining.

Biofertilizer Based on Biochar and Metal-Tolerant Plant Growth Promoting Rhizobacteria Alleviates Copper Impact on Morphophysiological Traits in Brassica napus L.

“…The optical density of extracts was measured at 470, 647, and 663 nm and the content of pigments was calculated according to Lichtenthaler [25]. The amount of soluble phenolic compounds (including flavonoids) in plant leaves was determined in 80%-ethanol extracts (24-h extraction in darkness) as described earlier [26]. The total phenolic content was measured in the reaction with the Folin-Ciocalteu reagent at 725 nm.…”

“…The content of free proline was determined after extraction in boiling water (95-100 • C). Staining was performed with a ninhydrin solution with the addition of glacial acetic acid in an equivalent ratio according to a modified method at a wavelength of 520 nm [26].…”