The existing forms of cadmium (Cd) in brown rice of two cultivars

a lowCd accumulating cultivar Guangyuanzhan No3

and a highCd accumulating cultivar Zhenguiai

were studied through solvent extraction and biochemical methods. The results showed that Cd was mostly existed in brown rice in complex forms and mainly in the protein binding forms. Among the main proteins Cd was mainly bound with globular and glutelin. In comparison with Guangyuanzhan No3

Zhenguiai was higher in proportion of 01 mol/L EDTA

25% NaCl and 02%NaOH extractableCd and had higher Cd percentage in globulin

which preliminary proved the difference between the two cultivars. Three protein absorption peaks (FI

FII and FIII) were identified in TrisHCl extraction of brown rice on Sephadex G 75. The distribution of Cd in the soluble fraction followed the same elution pattern as protein. While comparing the two rice cultivars Cd distribution in the three absorption peaks was different. In Zhenguiai the majority of soluble Cd was bounded to phytochelatins (PCs) or lowmolecularweight components with a molecular weight of ~3 kDa. However

the content of CdPCs in seed in the variety of Guangyuanzhan No3 was founded to be much lower than that in Zhenguiai

which possibly implying the difference of Cd allocation in PSC and nonPSC.