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Morphological and functional responses of a metal-tolerant sunflower mutant line to a copper-contaminated soil series

Kolbas, Aliaksandr, Kolbas, Natallia, Marchand, Lilian, Herzig, Rolf, Mench, Michel
Environmental science and pollution research international 2018 v.25 no.17 pp. 16686-16701
Helianthus annuus, antioxidant activity, biomarkers, carotenoids, chlorophyll, copper, dose response, environmental monitoring, hypocotyls, ionome, leaf area, leaves, median effective concentration, metal tolerance, mutants, photosynthesis, phytoaccumulation, phytotoxicity, plant response, polluted soils, roots, shoots, soil pore water, topsoil, wood preservation
The potential use of a metal-tolerant sunflower mutant line for biomonitoring Cu phytoavailability, Cu-induced soil phytotoxicity, and Cu phytoextraction was assessed on a Cu-contaminated soil series (13–1020 mg Cu kg⁻¹) obtained by fading a sandy topsoil from a wood preservation site with a similar uncontaminated soil. Morphological and functional plant responses as well as shoot, leaf, and root ionomes were measured after a 1-month pot experiment. Hypocotyl length, shoot and root dry weight (DW) yields, and leaf area gradually decreased as soil Cu exposure rose. Their dose-response curves (DRC) plotted against indicators of Cu exposure were generally well fitted by sigmoidal curves. The half-maximal effective concentration (EC₅₀) of morphological parameters ranged between 203 and 333 mg Cu kg⁻¹ soil, corresponding to 290–430 μg Cu L⁻¹ in the soil pore water, and 20 ± 5 mg Cu kg⁻¹ DW in the shoots. The EC₁₀ for shoot Cu concentration (13–15 mg Cu kg⁻¹ DW) coincided to 166 mg Cu kg⁻¹ soil. Total chlorophyll content and total antioxidant capacity (TAC) were early biomarkers (EC₁₀: 23 and 51 mg Cu kg⁻¹ soil). Their DRC displayed a biphasic response. Photosynthetic pigment contents, e.g., carotenoids, correlated with TAC. Ionome was changed in Cu-stressed roots, shoots, and leaves. Shoot Cu removal peaked roughly at 280 μg Cu L⁻¹ in the soil pore water.