Role of Phytochelatins in Cadmium Stress Tolerance in Plants

Ahmad, Javed; Ali, Arlene Asthana; Baig, Mohd Affan; Iqbal, Muhammad; Haq, Inamul; Qureshi, M. Irfan

doi:10.1016/b978-0-12-814864-8.00008-5

Cited by 44 publications

(33 citation statements)

References 141 publications

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“…It is largely accepted that the vacuoles of the root cells are the major sites of Cd sequestration in the free or chelated form [ 16 , 32 , 39 , 40 ]. Several studies revealed that most of Cd retained in the roots is immobilized in complexes containing PCs and related thiol compounds [ 25 , 27 , 41 , 42 ].…”

Section: Discussionmentioning

confidence: 99%

“…Several studies revealed that most of Cd retained in the roots is immobilized in complexes containing PCs and related thiol compounds [ 25 , 27 , 41 , 42 ]. Such ligands—directly derived from GSH—form complexes with Cd that accumulate into the vacuoles [ 28 , 30 , 32 ]. Since the activation of metabolic detoxification pathways based on the biosynthesis of thiols allows to retain Cd within the roots, we analyzed the effects of Cd exposure on NPT accumulation in the roots of the two rice accessions ( Figure 2 ).…”

Section: Discussionmentioning

confidence: 99%

“…Phytochelatins (PCs) and related thiols have been described as the principal Cd chelators in the root cells. They are a class of cysteine-rich peptides, non-translationally synthesized from glutathione (GSH) in a transpeptidation reaction catalyzed by the enzyme PC synthase (PCS) [ 29 , 30 , 31 , 32 ]. PCs form complexes with Cd that can be compartmentalized into the vacuoles, and thus retained within the root cells.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of Cadmium Root Retention for Two Contrasting Rice Accessions Suggests an Important Role for OsHMA2

Maghrebi

Baldoni

Lucchini

et al. 2021

Plants

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Two rice accessions, Capataz and Beirao, contrasting for cadmium (Cd) tolerance and root retention, were exposed to a broad range of Cd concentrations (0.01, 0.1, and 1 μM) and analyzed for their potential capacity to chelate, compartmentalize, and translocate Cd to gain information about the relative contribution of these processes in determining the different pathways of Cd distribution along the plants. In Capataz, Cd root retention increased with the external Cd concentration, while in Beirao it resulted independent of Cd availability and significantly higher than in Capataz at the lowest Cd concentrations analyzed. Analysis of thiol accumulation in the roots revealed that the different amounts of these compounds in Capataz and Beirao, as well as the expression levels of genes involved in phytochelatin biosynthesis and direct Cd sequestration into the vacuoles of the root cells, were not related to the capacity of the accessions to trap the metal into the roots. Interestingly, the relative transcript abundance of OsHMA2, a gene controlling root-to-shoot Cd/Zn translocation, was not influenced by Cd exposure in Capataz and progressively increased in Beirao with the external Cd concentration, suggesting that activity of the OsHMA2 transporter may differentially limit root-to-shoot Cd/Zn translocation in Capataz and Beirao.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Analysis of Cadmium Root Retention for Two Contrasting Rice Accessions Suggests an Important Role for OsHMA2

Maghrebi

Baldoni

Lucchini

et al. 2021

Plants

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“…And finally, thirdly GSH is known to be a substrate for synthesis of phytochelatins (the oligomeric form of GSH). Phytochelatins could form the phytochelatin-Cd complexes and similar to Cd(GS) 2 complexes, were sequestrated into the vacuoles (Yen et al 1999 ; Ahmad et al 2019 ).…”

Section: Discussionmentioning

confidence: 99%

Efficient antioxidant defence systems of spring barley in response to stress induced jointly by the cyst nematode parasitism and cadmium exposure

et al. 2020

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Aims This research aimed to establish how Hordeum vulgare responds to abiotic and biotic stress affecting in tandem. Methods Plants were inoculated with Heterodera filipjevi and treated with cadmium (Cd) concentration (5 μM) that can occur in the cultivated soil. To verify the hypothesis about participation of increased antioxidative defence in H. vulgare under stress, biochemical and microscopic methods were implemented. Results The amount of superoxide anions and hydrogen peroxide was diminished in plants that were both nematode-inoculated and cadmium-treated. Superoxide anions were rendered harmless by increased activity of superoxide dismutase, and H2O2 was scavenged via Foyer-Halliwell-Asada pathway. The unique enhanced antioxidant capacity of double stressed plants was also linked with the accumulation of S-nitrosoglutathione as nitrosoglutathione reductase activity was inhibited. Furthermore, stimulated activity of arginase in these plants could promote polyamine synthesis and indirectly enhance non-enzymatic antioxidant mechanism. Results indicate that different antioxidants operating together significantly restricted oxidation of lipids and proteins, thus the integrity of cell membranes and protein functions were maintained. Conclusions The ROS deactivation machinery in barley leaves showed an unusual response during stress induced by H. filipjevi infection and cadmium treatment. Plants could induce a multi-component model of stress response, to detoxify Cd ions and efficiently repair stress damage.

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“…PCs are considered as one of the major intercellular chelating ligands for Cd ions and their content is usually related to the metal concentration [40]. In their review papers, Sanità Di Toppi and Gabbrielli [1] and Ahmad et al [41] pointed out that accumulation of PCs is the main mechanism allowing plant cells to cope with Cd stress and the synergistic role of PCs with antioxidants is underlined. However, they also indicated that most these investigations were focused on acute Cd stress.…”

Section: Several Mechanisms Of CD Effect On the Uptake Of Essential Nmentioning

confidence: 99%

Metabolic responses of Carlina acaulis L. to chronic and acute cadmium stress: insights into chelation mechanisms, non-enzymatic antioxidants, and specialized metabolism

Dresler

Strzemski

Kováčik

et al. 2020

Preprint

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BackgroundChronic and acute stress can lead to completely different metabolic responses of plants exposed to the same abiotic factor. The effect of long-term chronic cadmium stress (ChS, 0.1 µM Cd, 85 days) or short-term acute cadmium stress (AS, 10 µM Cd, 4 days) on the physiology of Carlina acaulis L. (Asteraceae) and selected secondary metabolites was compared to identify specific physiological and biochemical reactions.ResultsThe bioconcentration of Cd in all analyzed organs was higher under AS in comparison with ChS (130 vs. 16 µg g-1 DW, 7.9 vs. 3.2 µg g-1 DW, and 11.5 vs. 2.4 µg g-1 DW in roots, leaves, and trichomes, respectively). The high concentration of Cd in the trichomes in the AS treatment might be an anatomical adaptation mechanism. ChS evoked an increase in the root biomass, whereas its impact on shoot biomass was not significant in any treatment. The amounts of ascorbic acid and the sum of phytochelatins were higher in the shoots, whilst organic acids (malic and citric) reached higher levels in the roots of plants from the ChS treatment. Glutathione depletion occurred in the shoots, but there was no change in its root level in both treatments. The amount of chlorogenic acid, but not that of ursolic and oleanolic acids, was increased under ChS. On the other hand, AS exposure elevated the level of ursolic and oleanolic acids, but not chlorogenic acid in the shoots. ConclusionsThese data indicate that ChS and AS induce different physiological and biochemical defense mechanisms. Both chelation and enhancement of the antioxidative machinery contribute to protection of C. acaulis exposed to long-term (chronic) Cd exposure and alleviate Cd toxicity effectively. However, triterpene acids were elevated only under AS treatment, which may suggest an instantaneous action of these metabolites under short-term acute Cd stress.

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Role of Phytochelatins in Cadmium Stress Tolerance in Plants

Cited by 44 publications

References 141 publications

Analysis of Cadmium Root Retention for Two Contrasting Rice Accessions Suggests an Important Role for OsHMA2

Analysis of Cadmium Root Retention for Two Contrasting Rice Accessions Suggests an Important Role for OsHMA2

Efficient antioxidant defence systems of spring barley in response to stress induced jointly by the cyst nematode parasitism and cadmium exposure

Metabolic responses of Carlina acaulis L. to chronic and acute cadmium stress: insights into chelation mechanisms, non-enzymatic antioxidants, and specialized metabolism

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