The Uptake of Copper by Aldama dentata: Ecophysiological Response, Its Modeling, and the Implication for Phytoremediation

Abstract

Aldama dentata Llave & Lex. is a plant native to Latin America that exhibits metallicolous populations. Its ecophysiological (EP) response to Cu stress, administered as graded soil concentrations (Cs )o f the fungicide copper(II) oxychloride, is examined in depth. Using a systems biology- and population dynamics-inspired approach, an r/K-driven model is proposed that satisfactorily explains the plant Cu concentration (Cp )v ersusCs EP response curves for the root, shoot, and whole plant. A. dentata was found to be a Cu excluder (ME). The dual role of Cu as a nutrient and toxin at low and high concentrations, respectively, manifested as a parabolic variation of the foliar area where the toxicity appeared as a second-order effect. The power-law variance of biomass (Bp) with Cp expected from the universal allometric scaling law of biology was loosely followed and is discussed in terms of the mode of Cu uptake by the plant and Cu's dual physiological role. Biometric growth indices reflected the impact of Cu on the photosynthetic energy harvest. The general applicability of the r/K-driven model was corroborated by its successful application to the published Cp-Cs data of the well-known Cu ME, Silene vulgaris .T her-K factors suggest a new quantitative manner of comparing the phytoavailability of the metal and the plant's accumulation capability across soil types. A. dentata with high root Cp but low Bp diminution could potentially find use as a Cu phytostabilizer.