Role of sulfate in detoxification of arsenate-induced toxicity in Zea mays L. (SRHM 445): nutrient status and antioxidants

Figures & data

Figure 1.  Levels of As (µg g⁻¹ dw) in the leaves (A) and roots (B), Cu in the leaves (C) and roots (D), Zn in the leaves (E) and roots (F) of Zea mays treated with arsenate and different levels of sulfur. All values are mean of four replicates±SD. Bars marked with same letters are not significantly different (Duncan's test, p<0.05).

Figure 2.  Levels of Fe (µg g⁻¹ dw) in the leaves (A) and roots (B), Mn in the leaves (C) and roots (D), Ca in the leaves (E) and roots (F) of Zea mays treated with arsenate and different levels of sulfur. All values are mean of four replicates±SD. Bars marked with same letters are not significantly different (Duncan's test, p<0.05).

Figure 3.  Levels of K (µg g⁻¹ dw) in the leaves (A) and roots (B), Na in the leaves (C) and roots (D), PO₄ in the leaves (E) and roots (F) of Zea mays treated with arsenate and different levels of sulfur. All values are mean of four replicates±SD. Bars marked with same letters are not significantly different (Duncan's test, p<0.05).

Figure 4.  Effect of arsenate treatment on Zea mays after 14 d, treated with sulfur without sulfur and 1 mM GSH. (A) C(+S); (B) C(−S); (C) As(9)(+S); (D) As(12)(+S); (E) As(9)(−S); (F) As(12)(−S); (G) As(9)(GSH); (H) As(12)(GSH). The scale in the figure represents 30 cm.

Figure 5.  (A) The effect of arsenate on fresh weight (g), (B) root length (cm), (C) shoot length, (D) total chlorophyll (mg g⁻¹ fw), (E) carotenoid (mg g⁻¹ fw), and (F) protein contents (mg g⁻¹ fw) of Zea mays after 7 and 14 d treated with As and different levels of sulfur. All values are mean of four replicates ±SD and bars marked with same letters are not significantly different (Duncan's test, p<0.05)

Table 1. Levels of malondialdehyde (µmol g⁻¹ fw), hydrogen peroxide (µg g⁻¹ fw), carbonyl, glutathione, glutathione oxidized (µg g⁻¹ fw), ascorbate (µM g⁻¹ fw), and Chl a/b ratio in Zea mays leaves treated with arsenate after 7 and 14 d.

	Treatments	MDA	H2O2	Carbonyl	GSH	GSSG	AsA	Chl a/b
7 d	C	10.42±2.34^ab	48.0±15.3^a	1.091±0.22^abc	590.9±20.87^c	6.4±0.4^a	1819.9±281.0^a	2.2
	C (−S)	9.34±2.33^a	68.4±14.4^ab	1.752±0.66^cde	–	–	2448.04±177.1^ab	3.3
	As (9) (+S)	12.41±2.46^ab	52.1±9.9^a	1.254±0.40^bcd	387.2±37.2^a	5.8±1.0^a	1975.3±291.6^a	2.2
	As (12) (+S)	11.76±2.29^ab	81.8±25.5^ab	1.934±0.05^de	489.3±69.8^b	6.01±1.0^a	1509.6±266.6^a	3.2
	As (9) (−S)	9.55±2.54^a	102.5±18.7^bc	1.299±0.39^bcd	–	–	2099.4±285.0^a	3.6
	As (12) (−S)	11.22±3.03^ab	200.7±67.9^d	2.185±0.10^e	–	–	2931.4±837.4^b	3.4
	As (9) (GSH)	14.30±1.84^b	138.5±24.3^c	1.854±0.57^de	630.6±4.9^cd	6.4±0.8^a	2228.2±463.3^ab	3.0
	As (12) (GSH)	13.16±0.57^b	77.9±3.0^ab	2.147±0.03^e	652.5±24.9 ^d	7.1±0.7^a	1783.2±160.6^a	2.7
14 d	C	10.48±1.40^BC	94.7±16.3^AB	0.526±0.16^A	457.4±148.4^A	3.6±0.7^A	1038.1±285.2^A	1.1
	C (−S)	6.82±0.78^A	251.5±30.7^D	1.929±0.63^DE	–	–	851.9±80.81^B	4.1
	As (9) (+S)	10.54±2.53^BC	181.3±23.8^C	1.250 ±0 .17^BCD	547.8±8.7^AB	3.3±0.3^A	1187.2±151.4^B	3.3
	As (12) (+S)	11.50±0.71^C	132.5±56.7^BC	1.722±0.40^BCDE	608.4±56.2^A	3.2±0.5^A	954.5±13.9 ^BC	2.7
	As (9) (−S)	9.33±0.67^B	251.0±47.6^D	2.026±0.09^E	–	–	1442.9±393.5^A	4.2
	As (12) (−S)	10.33±1.28^BC	346.6±42.6^E	1.311±0.50^BCD	–	–	2856.3±166.9^E	–
	As (9) (GSH)	10.30±0.87^BC	87.3±17.6^AB	1.017±0.15^AB	738.5±108.8^B	3.6±0.6^A	1841.5±552.8^D	2.3
	As (12) (GSH)	10.87±1.09^BC	54.4±12.9^A	1.579±0.30^BCDE	963.2±54.04^C	4.6±0.9^B	1564.4±390.1^CD	3.0
All values are mean of four replicates ±SD and values marked with same letters are not significantly different (Duncan's test, p<0.05).

Figure 6.  Effect of arsenate treatment (µg mg⁻¹) with (+S), (−S) and 1 mM (GSH) on the activities of different antioxidant enzymes in leaves of Zea mays after 7 and 14 d. (A) superoxide dismutase (U mg⁻¹ protein); (B) ascorbate peroxidase: (µmol min⁻¹ mg⁻¹ protein); (C) catalase (M min⁻¹ mg⁻¹ protein); (D) guaiacol peroxidase (mmol min⁻¹ mg⁻¹ protein); (E) glutathione reductase (U mg⁻¹ protein); (F) ascorbate oxidase (U mg⁻¹ protein). All the values are means of four replicates ±SD. Bars indicated by same letters are not significantly different (Duncan's Multiple Range Test, p<0.05).

Figure 7.  Native PAGE activities of different isofoms of (A) superoxide dismutase (SOD); (B) ascorbate peroxidase (APX); (C) guaiacol peroxidase (basic) (POD Basic); (D) guaiacol peroxidase (acidic) (POD Acidic) in leaf extract of Zea mays treated with arsenate and different sulfate regimes.