Table 2.

Polyamine mediated antioxidant defense in different plant species under metal/metalloid stresses.

Crop Species	Metal Exposure	Changes in Endogenous PAs Level	Exogenous PAs Applications	Antioxidant Defense System	References
Triticum aestivum L.	2 mM Cd as CdCl2 and 2 mM as PbCl2 for 45 d	-	0.25 mM Spm, 0.50 mM Spd, and 1 mM Put as seed priming or as a foliar spray at 20, 40, and 60 DAS	Enhanced the activity of SOD, CAT, POD, and GR Improved ascorbic acid oxidase (AAO), and polyphenol oxidase (PPO) activities	Taie et al. [12]
T. aestivum	2 mM as PbCl2 for 45 d	-	0.25 mM Spm, 0.50 mM Spd, and 1 mM Put as seed priming or as a foliar spray at 20, 40 and 60 DAS	Enhanced the activity of SOD, CAT, POD, GR Improved ascorbic acid oxidase (AAO), and polyphenol oxidase (PPO) activities	Taie et al. [12]
T. aestivum	2 mM CdCl2 for 58 d	-	0.25 mM Spm, 0.50 mM Spd, 1.0 mM Put as seed priming and later foliar spraying	Increased POD and CAT activity Decreased SOD activity	Rady et al. [28]
T. aestivum	30 µM AlCl3	Increased Spd	Put, 2 mM as cotreatment	Inhibited plasma membrane NADPH oxidase and CW-PAO activity in Al-stressed wheat and thus reduced H2O2 accumulation Decreased SOD, CAT, POD, APX, GR, GST activities Decreased LOX activity and Thiobarbituric acid (TBARS) content	Yu et al. [29]
T. aestivum	2 mM Cd	Increased endogenous Spm and Spd upon Cd exposure	-	Increased AsA, GSH content with higher SOD, CAT, POD activity	Howladar et al. [30]
T. aestivum	1 mM Cd as CdCl2	Increased PAs content by pretreated seedlings under stress affection	2 mM Spd or 2 mM Spm as a seed treatment for 6 h	Increased AsA and GSH content Enhanced SOD and CAT activity Decreased POX and APX activity Lowered H2O2 and MDA generation	Rady and Hemida [11]
T. aestivum	0.5 mM Cd as CdCl2	Increased PAs content such as Put, Spd, and Spm	0.5 and 1.0 mM Spm	Decreased ADC and ODC with lowered DAO activities Lowered SOD, GPX, with increased of GR Increased APX activity under Cd stressed the plant Increased GSH content under Cd stress while decreased at Cu treated plant	Groppa et al. [37]
T. aestivum	0.5 mM Cu as CuCl2	-	0.5 and 1.0 mM Spm	Decreased ADC and ODC with lowered DAO activities Lowered SOD, GPX, with increased of GR Increased APX activity under Cd stressed the plant Increased GSH content under Cd stress while decreased at Cu treated plant	Groppa et al. [37]
Oryza sativa L.	5 mM CdCl2	-	5 mM Put, 5 mM Spd, and 5 mM Spm	Increased protein content under Cd exposure Increased AsA and GSH content at Cd stressed rice Decreased SOD, CAT, APX, GR and POX activity Reduced H2O2 and MDA content significantly	Hsu and Kao [38]
Vigna radiata	1.5 mMCdCl2	Increased Spd and Spd content with decrease the Put/PAs ratio	Put, 0.2 mM, as pretreatment for 24 h	Boosted up AsA and GSH content, while DHA content was decreased Increases AsA/DHA ratio and decreased GSH/GSSG ratio Increased SOD, CAT, APX, MDHAR, DHAR and GST activities Decreased the ROS generation with lower malondialdehyde (MDA) and lipoxygenase (LOX) activity Improved the glyoxalase system by increasing Gly II activity with lowered MG content	Nahar et al. [1]
V. radiata	200 mg kg−1 soil as ZnSO4·7H2O	-	1.0 mM Spd, foliar application	Increased SOD, CAT and POX activity	Mir et al. [32]
Chlorella vulgaris Beijerinck	100 µM of Cd as Cd(NO3)2·4H2O	-	100 μM Spd	Increased AsA and GSH accumulation Increased SOD, CAT, and APX activity Decreased H2O2 and MDA generation	Piotrowska-Niczyporuk et al. [33]
C. vulgaris	100 µM Pb as, Pb(NO3)2	-	100 μM Spd	Increased AsA and GSH accumulation Increased SOD, CAT, and APX activity Decreased H2O2 and MDA generation	Piotrowska-Niczyporuk et al. [33]
C. vulgaris	100 µM Cu as Cu(NO3)2·3H2O	-	100 μM Spd	Increased AsA and GSH accumulation Increased SOD, CAT, and APX activity Decreased H2O2 and MDA generation	Piotrowska-Niczyporuk et al. [33]
Raphanus sativus	1.2 mM Cr as (K2CrO4)	Increased Put and Spd content	1 mM Spd as cotreatment	Increased GSH, AsA, contents Enhanced accumulation of osmolyte (Pro, GB, and Phenol) Increased SOD, and GR activity where decrease Cat and POD activities in Cr-stressed plants Lowered NADPH oxidase activity Decreased MDA and H2O2 production	Choudhary et al. [34]
Salix matsudana Koidz.	0.05 and 0.10 mM Cd	Increased endogenous Spd and Put contents	0.25 mM Spd as cotreatment for 3 d	Upregulated SOD, CAT, GR GPX, and APX activities Enhanced AsA and GSH contents Increased endogenous NO content Decreased MDA, O2•−, and H2O2 production	Tang et al. [35]
Helianthus annuus	0.5 mM Cd as CdCl2	Increased endogenous Put and Spd levels	1.0 mM Spd and Spm	Increased APX and GR activity under Cd stress while reducing the SOD activity Enhanced the SOD and GR activity with lower APX activity under Cu stressed plant	Groppa et al. [39]
H. annuus	0.5 mM Cu as CuCl2	Increased endogenous Put and Spd levels	1.0 mM Spd and Spm	Increased APX and GR activity under Cd stress while reducing the SOD activity Enhanced the SOD and GR activity with lower APX activity under Cu stressed plant	Groppa et al. [39]