Table I.

Effect of sulfate withdrawal and Cd exposure on NPT, total glutathione, GSH, GSSG, Cys, and γ-EC contents of maize roots

Seedlings grown for 3 d in complete nutrient solutions were transferred and grown for additional 3, 6, and 12 h periods in complete nutrient solutions supplemented or not with 10 μm CdCl₂ (Cd) or in a minus-sulfate solution (−S). Each thiol compound is expressed as GSH equivalents. The values relative to the untreated plants are reported only for t₀ (0 h) because they did not significantly vary during the experimental period. Values are means ± se of three experiments run in triplicate (n = 9). Asterisks indicate significant differences between the values of treated and control (0 h) plants (P < 0.05).

	Thiol Concentration
	0 h	3 h		6 h		12 h
			−S	Cd	−S	Cd	−S	Cd
	nmol GSH equivalent g−1 fresh weight
NPTs	220 ± 14	221 ± 11	300 ± 13	216 ± 15	451 ± 21*	110 ± 20*	900 ± 42*
Total glutathione	196 ± 7	194 ± 6	99 ± 5*	192 ± 7	96 ± 5*	102 ± 6*	97 ± 5*
GSH	155 ± 9	155 ± 8	48 ± 8*	152 ± 10	48 ± 7*	82 ± 8*	46 ± 8*
GSSG	41 ± 2	39 ± 2	51 ± 3*	40 ± 3	48 ± 2	20 ± 2*	51 ± 3*
Cys	8.3 ± 0.3	8.6 ± 0.4	8.5 ± 0.3	8.2 ± 0.4	9.5 ± 0.3*	7.8 ± 0.3	12.4 ± 0.3*
γ-EC	3.6 ± 0.2	3.5 ± 0.2	3.8 ± 0.2	3.7 ± 0.2	5.2 ± 0.3*	3.1 ± 0.2	11.3 ± 0.5*