Subcellular Distribution Of Salt Ions And Cd In Amaranth Under NaCl Stress

In this paper, a hydroponic experiment was carried out to investigate the subcellulardistribution and translocation characteristics of salt ions(Na⁺、K⁺、Ca²⁺、Mg²⁺) and Cd insalt-tolerant and salt-sensitive Amaranth under different NaCl stress. The results providesome new clues for the accumulation and translocation mechanism of Cd in crops in thesubcellular scale.In the experiment, one Cd concentration and a series of NaCl concentrations were set toinvestigate the subcellular distribution of salt ions and Cd in different parts of Amaranthwith differential centrifugation technique. The results show that, Na⁺, K⁺and Mg²⁺mostlylocate in the cell wall （FⅠ） and cytoplasmic supernatant （FⅢ） of Amaranth. With the increaseof NaCl concentration, Na⁺contents in the three subcellular components rise sharply, whileK⁺and Mg²⁺contents in that decrease to some extent, which means absorption of necessaryelements are inhibited by ecessive accumulation of Na⁺contents. More than50%of Ca²⁺contents, which decrease as the increase of NaCl concentration, locate in the cell wall （FⅠ）of Amaranth. Most Cd contents in Amaranth are found in the cell wall （FⅠ）, followed by thecytoplasmic organelles （FⅡ）, and only5%of Cd contents in Amaranth lacate in thecytoplasmic supernatant （FⅢ）. Compared with the control treatment, Cd contents in the cellwall （FⅠ） of the roots and shoots of Amaranth decrease significantly under NaCl stress.The accumulation and translocation characteristics of salt ions and Cd were alsostudyed. The results show that, the order of Na⁺concentrations in different organs isshoot>root>leaf, and a dramatic increase is found along with the rise of NaCl concentration;the order of K⁺, Ca²⁺and Mg²⁺concentrations in different organs is leaf>root> shoot, and asignificant decrease is found comparing with that in the control treatment; The order of Cdconcentrations in different organs is leaf>root> shoot, and a significant decrease is foundcomparing with the control treatment. There is a significant reduction in TSM，Na（root-shoot）ofAmaranth under NaCl stess, while a sharp rise is found in TSM，Na（shoot-leaf）. However, bothTSM，Na（root-shoot）and TSM，Na（shoot-leaf）of Amaranth decrease along with the increase of NaClconcentration from2.5g/L to10.0g/L. The TF（root-shoot）and TF（shoot-leaf）of Amaranth also increase comparing with the control treatment.