Dynamic changes of cadmium and non-protein thiol in different organs of different soybean genotypes under cadmium stress

Objective Dynamic changes of cadmium and non-protein thiols in different soybean genotypes were researched to investigate effects of non-protein thiols on Cd tolerance and accumulation of soybean.

Method The soybean varieties of Zhonghuang24 and Huaxia3 were planted in the pots with contaminated soil. Roots, shoots and leaves were collected in different periods. Cd tolerance indexes (including root and shoot fresh mass), Cd accumulation and the concentrations of non-protein thiols including the total of non-protein thiol peptides (NPT), glutathione (GSH) and phytochelatins(PC) of soybeans in different periods were determined.

Result The resistance indexes of Zhonghuang24 were significantly lower than those of Huaxia3 in different periods at the Cd concentration of 10 mg·kg^-1, and Cd accumulations in all organs were higher than those of Huaxia3 after flowering stage (especially at pod and mature stages). The NPT, GSH and PC concentrations increased in root and reduced in leaf along with the development progress, and the effects of non-protein thiols in Zhonghuang24 under Cd stress were stronger those of Huaxia3. The correlation analysis indicated that there was a positive correlation between thiol concentration in root and the Cd concentration in all organs, especially at mature stage. There was a negative correlation between PC concentrations in stem and leaf after flowering stage, especially more significant at pod and mature stages.

Conclusion The concentrations of thiols and Cd in soybean organs show complex changes at different growth stages under Cd stress. Non-protein thiols play multiple roles in Cd detoxification and transportation at different growth stages.