Calcium induces phytochelatin accumulation to cope with chromium toxicity in rice (Oryza sativa L.)

Figures & data

Table 1. Root length, root dry weight, shoot height, shoot dry weight, level of photosynthetic pigment (chl a and chl b) in leaves and water retention rate of root and shoot of Oryza sativa seedlings. Means (±SD) were calculated from four replications (n = 4) for each treatment. Values with different letters are significantly different at ≤ .05 applying test.

Treatment	Root length (cm)	Root dry weight (mg)	Shoot height (cm)	Shoot dry weight (mg)	total chl a and b (µg/gm FW)	Carotenoids (µg/gm FW)	Water retention rate root (%)	Water Retention rate shoot (%)
Control	1.55 ± .129^b	1.7 ± .41^b	3.88 ± .83^b	3.6 ± .83^b	49.69 ± 3.760^a	111.46 ± 5.95^a	79	78
Cr+	.975 ± .125^a	1.03 ± .69^a	2.73 ± .84^a	2.8 ± .93^a	55.66 ± 11.08^a	146.49 ± 14.3^b	64	70
Cr^++CaC2	1.425 ± .65^b	1.85 ± .55^b	3.9 ± .50^b	3.72 ± .35^b	51.10 ± 10.78^a	99.68 ± 18.0^a	71	75
Cr^−+CaCl2	1.375 ± .55^b	1.8 ± .32^b	3.9 ± .87^b	3.73 ± 1.24^b	50.48 ± 19.89^a	113.96 ± 7.95^a	72	75

Figure 1. Chromium and iron concentration in the roots and shoots and their translocation rate (%) from root to shoot of 7 days old rice plants grown under different growth conditions of Cr and Ca⁺. Different letters in each column indicates significant differences between means ± SD of treatments (n = 4) at a p < .05 significance level.

Figure 2. Total soluble protein content and electrolytic leakage in the roots of 7 d old rice plants grown under different growth conditions of chromium and calcium. Different letters in each column indicate significant differences between means ± SD of treatments (n = 4) at p < .05 significance level.

Figure 3. Malondialdehyde content in the roots of 7-day-old rice plants grown under treatment with or without chromium and calcium. Different letters in each column indicate significant differences between means ± SD of treatments (n = 4) at p < .05 significance level.

Table 2. Enzymatic activities and hydrogen peroxide content in roots of rice seedlings, cultivated for 7 days in nutrient medium with calcium in presence or absence of chromium. Different letters in each column indicated significant differences between means ± SD of treatments (n = 4) at p ≤ .05 significant level.

Enzymes	Control	Cr^+	Cr^++CaCl2	Cr^-+ CaCl2
CAT (U min^−1mg^−1)	0.347 ± 0.074^b	0.138 ± 0.084^a	0.636 ± 0.073^c	0.298 ± 0.073^b
POD (U min^−1 mg^−1)	0.890 ± 0.020^c	0.541 ± 0.084^a	0.776 ± 0.003^b	0.740 ± 0.028^b
SOD (U min^−1 mg^−1)	0.209 ± 0.005^a	0.170 ± 0.0563^a	0.218 ± 0.0558^a	0.184 ± 0.027^a
GR [nmol.NADH. min^−1 gm protein^−1]	0.189 ± 0.038^b	0.109 ± 0.014^a	0.194 ± 0.014^b	0.105 ± 0.014^a
H2O2 (µgg^−1 FW)	5.3 ± 0.357^b	7.893 ± 0.328^c	4.351 ± 1.163^a	5.583 ± 0.608^b

Table 3. The level of glutathione, phytochelatin and proline concentrations in roots of 7-day-old seedling grown in nutrient medium with calcium in presence or absence of chromium. Different letters in each column indicate significant differences between means ± SD of treatments (n = 4) at p ≤.05 significant level.

Treatment	Control	Cr	Cr^++CaCl2	Cr^-+CaCl2
Glutathione (µgg^−1)	4.27 ± 0.35^a	4.24 ± 0.20^a	5.55 ± 0.04^b	4.17 ± 0.22^a
Phytochelatin (µgg^−1)	13.05 ± 0.10^a	15.57 ± 0.21^b	23.34 ± 0.47^d	17.75 ± 0.39^c
Proline (µgg^−1)	63.48 ± 13.16^a	119.64 ± 18.13^b	106.00 ± 13.89^b	102.14 ± 9.75^b