锌对粳稻幼苗镉吸收转运特性的影响

采用水培实验,研究了镉胁迫下粳稻幼苗的生长发育特征及镉和锌的吸收转运特性。结果表明,施加1.2 mmol·L~(-1)及1.4mmol·L~(-1)锌能显著增加根尖数目和根系及地上部的生物量,并使根系中的镉积累量分别下降86.4%和97.5%,地上部镉积累量分别下降62.6%和73.3%。根系和地上部的镉主要分布在细胞壁(F1)和胞液(F3)中,细胞器(F2)中的镉含量很少,只占根系镉总量的5.4%和地上部镉总量的9.4%。锌降低了各亚细胞组分中镉的含量,提高了镉在F3中的分配比例。当锌使根系F3中的镉浓度降低到12.8 mg·kg~(-1)FW以下时,镉从根系F3中向地上部转运的比率显著增加,但转运量只有2.7μmol·L~(-1)Cd~(2+)(无锌添加)处理组的26.9%~46.1%。

Effects of zinc supply on absorption and translocation of cadmium in rice seedlings

Plant nutrition may influence the uptake of heavy metals by plants. Deficiency or toxicity of metal cations in soils reduces plant growth, crop yield, and the quality of plant foodstuff. Zinc(Zn)is an essential micronutrient for plants. Controlling Zn content in plant tis-sues is critical to plant normal growth and development. Many transporters and channels in the plasma membranes of plant cells are thought to balance the concentrations of essential metals such as Zn, and to unselectively transport toxic elements, e.g. cadmium(Cd). However, the molecular bases of the interactions between Zn and Cd remains poorly understood. In this study, the effects of different Zn2+concentrations on the seedlings growth, the uptake and translocation of Cd2+and Zn2+by japonica rice seedlings under Cd2+stresses were studied in solution culture. Rice plants were grown for 5 days in nutrient solution containing two levels of Cd (0μmol·L-1 and 2.7μmol·L-1)and three levels of Zn(0 mmol·L-1, 1.2 mmol·L-1, and 1.4 mmol·L-1). Results showed that supplying 1.2 mmol·L-1 and 1.4 mmol·L-1 Zn2+significantly in-creased the number of root tips as well as roots and shoots biomass of rice seedlings, which decreased root Cd2+by 86.4%and 97.5%, and shoot Cd2+by 62.6%and 73.3%, respectively. Most Cd2+was distributed in the cell wall(F1)and cell sap(F3)of roots and shoots. Cadmi-um in the organelle (F2)parts was only about 5.4%in roots and 9.4%in shoots. Adding Zn2+significantly reduced Cd concentrations in F1 and F3 of roots, but increased Cd2+distribution percentages in F3 of roots. Under exogenous Zn2+, Cd concentrations in root cell sap were lower than 12.8 mg·kg-1 FW, whereas Cd2+translocation ratio from root cell sap to shoot was significantly enhanced.