Functional characterisation of two phytochelatin synthases in rice (Oryza sativa cv. Milyang 117) that respond to cadmium stress

Abstract

Cadmium (Cd) is one of the most toxic heavy metals and a non‐essential element to all organisms, including plants; however, the genes involved in Cd resistance in plants remain poorly characterised. To identify Cd resistance genes in rice, we screened a rice cDNA expression library treated with CdCl2 using a yeast (Saccharomyces cerevisiae) mutant ycf1 strain (DTY167) and isolated two rice phytochelatin synthases (OsPCS5 and OsPCS15). The genes were strongly induced by Cd treatment and conferred increased resistance to Cd when expressed in the ycf1 mutant strain. In addition, the Cd concentration was twofold higher in yeast expressing OsPCS5 and OsPCS15 than in vector‐transformed yeast, and OsPCS5 and OsPCS15 localised in the cytoplasm. Arabidopsis thaliana plants overexpressing OsPCS5/‐15 paradoxically exhibited increased sensitivity to Cd, suggesting that overexpression of OsPCS5/‐15 resulted in toxicity due to excess phytochelatin production in A. thaliana. These data indicate that OsPCS5 and OsPCS15 are involved in Cd tolerance, which may be related to the relative abundances of phytochelatins synthesised by these phytochelatin synthases.

Functionalized Glutathione on Chitosan-Genipin Cross-Linked Beads Used for the Removal of Trace Metals from Water

“…As shown in Figure 7 , a significant difference was noticed between the adsorption of metals on CS beads without GSH and CS-GG beads, which was correlated with the amount of functionalized GSH on CS-GG beads. In fact, it is well known that GSH can make complexes with metals due to the amino acid cysteine present in the γ -Glu-Cys-Gly structure [ 44 , 45 ]. Concerning the removal of Cu(II), only the CS nanofibrils had a higher adsorption capacity than our CS-GG beads.…”

“…In particular, phytochelatins (PCs) are well-known thiol polypeptides, consisting of a chain of 2 to 11 units of glutathione ( γ -L-glutamyl-L-cysteinylglycine, GSH). In plant cells, these compounds are chelators involved in the transport of metals into the vacuole, maintaining the homeostasis of intracellular concentration of metals [ 44 ]. Since the synthesis of PCs is costly, its repetitive subunit GSH can represent a more practical alternative.…”

Responses of antioxidant enzymes and key resistant substances in perennial ryegrass (Lolium perenne L.) to cadmium and arsenic stresses

“…And the results confirmed that the PCs contents in roots increased. GSH also can directly complex with Cd and As to reduce toxicity so as to alleviate some toxicity in the roots [ 31 ]. Under the interaction of Cd and As, the contents of NPT and GSH in perennial ryegrass were positively correlated with the contents of Cd and As ( P < 0.01), which showed that with the increase of Cd and As contents accumulated in perennial ryegrass, the NPT contents in vivo increased and induced GSH to synthesize PCs.…”

Nanoparticles mediated cadmium toxicity amelioration in plants

“…The first line of defense is scavenging of Cd in root vacuole by low molecular weight organic acids, polysaccharides and non-protein thiol (NPT, phytochelatin) compounds (55,56) preventing its translocation to shoots (3). Sharp rise in the synthesis of Cd chelator low molecular weight peptide Phytochelatin (PC) is well documented in Cd stressed Eichhornia crassipes (55), Oryza sativa (57) and Arabidopsis (58) by upregulating phytochelatin synthase 1 gene. PC is well equipped to scavenge Cd for its detoxification.…”