Physiological and Biochemical Response of Alternanthera bettzickiana (Regel) G. Nicholson under Acetic Acid Assisted Phytoextraction of Lead

Abstract

Heavy metals (HMs) stress causes severe damage to physiology and biochemistry of plant species leading to stunted growth and low yield. Phytoremediation via phytoextraction, a viable low-cost and environment-friendly alternative to other techniques that are often too expensive, impractical and hazardous. However, phytoextraction potential, physiological and biochemical response of various plant species against HMs stress is not fully understood. Among other HMs, lead (Pb) is an inorganic pollutant with deleterious biotic effects. Bioavailability and mobility of the Pb can be enhanced by addition of organic acids. A pot scale experiment was done to assess the effects of Pb on Alternanthera bettzickiana (Regel) G. Nicholson and its ability to accumulate Pb with or without acetic acid (AA). The Results showed that Pb caused significant damage in A. bettzickiana, and its ecotoxicity was evident from increased levels of lipid peroxidation up to 107% under Pb stress. The significant decrease in plant height (32%), root length (21%), leaf area (38%) and number of leaves per plant (46%) was observed. On the other hand, application of AA to Pb stressed plants reduced the oxidative damage by further enhancing the activities of ascorbate peroxidase (APX) and catalases (CAT) up to 16% and 21% respectively. Moreover, addition of AA significantly improved plant total chlorophylls (15%) and carotenoids (50%). The application of AA also promoted Pb accumulation in leaf, stem and roots up to 70%, 65% and 66% respectively. This research concluded that AA has the ability to enhance the phytoextraction of Pb and support the plant growth and physiology under Pb stress condition.

A Comprehensive Review on the Heavy Metal Toxicity and Sequestration in Plants

“…Since the accumulation of HMs in the plants leads to adverse changes in the primary photosynthetic organ leaves, a decline in the rate of photosynthesis can be presumed. Literature hints that the impact of HMs on photosynthetic machinery depends on the reactivity and concentration of HMs in leaves, which subsequently affects light capture, electron transport, and activities of photosynthetic enzymes including RuBisCO ( Figure 2 ) [ 71 , 72 , 73 ].…”

“…Other plants experiencing toxicity of a variety of HMs also showed a similar drop in the photosynthesis and all of these studies collectively suggested that the decline in photosynthesis is majorly because of the decrease in the chlorophyll concentrations. Based on the literature evidence, it can be concluded that HMs can target chlorophyll in any of three ways: (1) by enhancing the activity of chlorophyllase enzyme [ 73 ]; (2) by causing oxidation/reduction of chlorophyll molecules by the HM toxicity induced ROS [ 78 , 79 , 80 ]; and (3) inhibition of chlorophyll biosynthesis as some of the HMs such as Hg, Cu, Pb, Ni, Cd, and Zn are able to replace the Mg in the porphyrin ring of the chlorophyll molecules [ 45 , 74 , 81 , 82 , 83 , 84 , 85 ]. Besides, phaeophytization of chlorophyll molecules because of the replacement of Mg 2+ ions by H + ions has also been reported in Eudorina unicocca and Chlorella kessleri under Cr-toxicity [ 86 ].…”

The Effect of The Herbicide of Glyphosate (Nphosphonomethyll Glycine) On Photosynthetic Pigments And Photosynthetic Activity of Basil (Ocimum Basilicum L.) By Laser-Induced Chlorophyll Fluorescence Spectroscopy

“…The plants were sprayed with different concentrations of glyphosate beginning after one week of glyphosate purchase and with 5 replicates per condition and 60 replicates per experiment. Levels of chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids were determined spectrophotometrically [17]. After treatment, the topmost fully expanded leaves were weighed and dipped in 85% (v/v) aqueous acetone to extract chlorophyll pigments.…”

“…Absorbances at 452.5 nm, 644 nm, and 663 nm were then measured relative to a blank sample of 85% liquid acetone. Levels of chlorophyll a and b, total chlorophyll, and carotenoids were determined spectrophotometrically using the following equations (where E stands for absorbance at the indicated wavelength) [17]: The absorbance of centrifuged, transparent acetone over the range of 380-700 nm was estimated using Spectrophotometer (JASCO Model V-670).…”

Phytoremediation potential of Pistia stratiotes, Eichhornia crassipes, and Typha latifolia for chromium with stimulation of secondary metabolites

“…Chromium (Cr) is a toxic metal which is mainly released from tanning industries [ 3 ]. It is both a toxic and a non-essential element [ 6 ]. Plants have specific transporters for the uptake and transport of mineral ions required for various metabolic processes.…”