Subcellular Distribution Characteristics Of Cadmium And Their Effects On Cd Accumulation In Different Rice(Oryza Sativa)

In order to reduce the harm of Cd to human body,we should cultivate Cd low accumulation rice varieties in the safe production of rice.Rice varieties were Overwintering Rice,R1088(low Cd accumulated in grain),IR34582 and toojing 558(high Cd accumulated in grain).Cadmium concentrations were 0 mg·kg-1,5 mg·kg-1,and 25 mg·kg-1.Distribution characteristics of cadmium in different rice varieties and their effects on Cd accumulation in different tissues at different growth stages.The results thowed:(1)The distribution of Cd in rice root,stem,leaf sheath and leaf subcell under Cd stress showed cell wall(F1)> soluble part(F4)> cell membrane(F2)and organelle(F3).With the increase of Cd stress concentration,the content of Cd increased.Under Cd stress,the content of cell wall,organelle,cell membrane and soluble part of Cd in Cd low accumulation rice varieties were all significant.The content of Cd in cell wall,organelle,cell membrane and soluble fraction of stem,leaf sheath and leaf was significantly lower than that of Cd,but that of Cd was higher than that of rice.(2)The content of Cd in each tissue area of rice increased with the increase of Cd concentration,and Cd mainly concentrated in the root system.The tillering stage was concretely represented by root > stem > leaf sheath > leaf.The heading stage was concretely represented by root > stem > leaf sheath > leaf > ear.The filling stage was concretely represented by root > stem > leaf sheath > leaf > grain.The maturity stage was concretely expressed as root > stem.> leaf sheath > leaf > brown rice;Under the stress of Cd,the content of Cd in root of Cd low accumulation rice was significantly higher than that of high accumulation of Cd,while the content of Cd in stem,leaf sheath,leaf,ear,grain and brown rice was significantly lower than that of Cd high accumulation rice(p<0.05).Under Cd stress,Cd low accumulated rice varieties Overwintering Rice and R1088TFroot-stem,TFstem-grain,TFleaf sheath-grain and TFleaf-grain was significantly lower than that of Cd,high accumulation rice variety IR34582 and toojing 558(p<0.05).(3)Under Cd stress,the rice varieties Overwintering Rice and R1088 with low Cd accumulation TFroot-stem at tillering stage,heading stage,filling stage and mature stage were significantly lower than those of high Cd accumulated rice varieties IR34582 and toojing 558.Division of the upper part of the ground TF stem-leaf sheath,TF stem-leaf and TF leaf sheath-leaf,TFroot-stem,TFstem-ear,TFleaf sheath-ear and TFleaf-ear at heading stage,TFroot-stem,TFstem-grain,TFleaf sheath-grain,TFleaf-grain atfilling stage,and mature stage of TFroot-stem,TFstem-grain,TFleaf sheath-grain and TFleaf-grain are also significantly lower than those of high accumulating rice varieties IR34582 and toojing 558.(4)The correlation analysis between the transfer coefficient and the Cd subcellular distribution ratio between different tissues of different rice varieties showed that after the root accumulation of Cd in the whole growth period of rice,the cell wall in the root hindered the upward transport,and the soluble part drove the Cd to transport to the upper part of the ground,and the cell wall in the shoot was hindered by the same hindrance to the transport of the Cd into the grain.The accumulation of Cd from the soluble part to the grain;Under certain Cd concentration,the cell membrane and organelles in rice roots at the tillering stage,heading stage and mature stage can also drive Cd to the upper part of the ground,and ultimately affect the accumulation of Cd in grain rice.