Abstract
Hyperaccumulation of heavy metals is substantial in some hyperaccumulators; however, few studies have been conducted to reveal the effect of light irradiation on the variations of representative amino acids and photosynthetic indices, which can represent the antioxidant capacity of plants during phytoremediation. The physiochemical responses of Arabidopsis thaliana to Cd stress were compared during six light irradiation treatments. The results of the experiment showed that the stress adaptation of A. thaliana was enhanced in all light irradiation treatments, except for monochromatic blue-light irradiation. The concentrations of glutamic acid and glutamine decreased significantly in pure blue light compared with the other treatments. The decrease in the concentrations of these two amino acids might be induced by an intensive biosynthesis of defensive factors, as manifested in the declined photosynthetic indices. Concentrations of aspartic acid and asparagine involved in the ammonification, absorption, and transportation of nitrogen in vascular plants increased in the red and blue combined irradiation treatments compared with the control, corresponding to the improved photosynthetic capacity of the species. The concentration of proline, which can represent environmental stresses including metal toxicity and excessive light energy, generally increased with an increasing ratio of blue light. This study proposes the key roles of amino acids and photosynthetic indices in light-motivated Cd pollution responses in A. thaliana.
Highlights
With the rapid development of the economy and society, environmental contamination has become increasingly severe
Light irradiation significantly enhanced the biomass of the plant roots compared with the control, except for monochromatic blue light, which resulted in the lowest value at the termination of the treatment (Figure 1)
A. thaliana could benefit from combinations of blue and red light, especially B10 and B50, which resulted in better biomass generation and Cd accumulation capacity
Summary
With the rapid development of the economy and society, environmental contamination has become increasingly severe. Cd is regarded as one of the most toxic heavy metals to plants and animals owing to its high bioavailability and toxicity [1]. 30 million kilogram of Cd is discharged into environmental media annually, with an estimated 13 million kilograms released from anthropogenic activities [2]. Electronic waste (e-waste) recycling is one of the most environmentally harmful anthropogenic activities. The contaminated soils treated in the present study were sampled from an e-waste disassembling and recycling town located in southern China. A large area of soils in the town has been polluted by disassembling activities owing to primitive dismantling methods [3]
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