锰离子浓度及其转运通道对水稻幼苗镉吸收转运特性的影响

Effects of manganese concentrations and transporters on uptake and translocation of cadmium in rice seedlings

为探明锰(Mn)及其转运通道对水稻镉(Cd)吸收转运特性的影响,以水稻幼苗为材料进行水培试验,对幼苗根系和地上部Cd、Mn的积累特征及其与P-型ATP酶和非选择性阳离子通道(NSCCs)活性的关系进行研究。结果表明,0.8~1.6 mmol·L^(-1)Mn能显著降低水稻根系和地上部的Cd含量,并能提升水稻细胞壁中Cd的分配比率和降低胞液中Cd的分配比率。在含4.5μmol·L^(-1)Cd和1.6 mmol·L^(-1)Mn的营养液中,NSCCs对水稻根系和地上部Cd含量的贡献率分别为34.9%和17.0%,P-型ATP酶的贡献率分别为24.7%和7.6%;NSCCs对水稻根系和地上部Mn的贡献率分别为24.0%和10.3%,明显低于其对Cd的贡献率,而P-型ATP酶对根系和地上部Mn的贡献率分别为69.5%和20.3%,显著高于其对Cd的贡献率。综上认为,Cd主要通过离子通道进入水稻根系细胞,Mn主要通过载体蛋白进入水稻根系细胞。Mn可能通过竞争离子通道和载体蛋白来抑制水稻幼苗对Cd的吸收和转运。

Heavy metal uptake by plants is influenced by coexisting ions. In this study, the effects of manganese（Mn）and its transporters on uptake and translocation of cadmium（Cd）in rice seedlings, the accumulation characteristics of Cd and Mn as well as their relationships with nonselective cation channels（NSCCs）and P-ATPase were studied under hydroponic conditions. Experimental results showed that at 0.8 mmol·L-1 to 1.6 mmol·L-1 of solution Mn, Cd accumulations were reduced both in roots and shoots, but the percentages of Cd distribution in the cell wall was increased, while that in solube fraction was decreased. In the solution with 4.5μmol Cd·L-1 and 1.6 mmol Mn·L-1, the per-centages of NSCCs contributions to the accumulation of Cd in roots and shoots were 34.9%and 17.0%, and those of P-ATPase were 24.7%and 7.6%, respectively. However, the percentages of NSCCs contributions to the accumulation of Mn in roots and shoots were 24.0% and 10.3%,those of P-ATPase to the accumulation of Mn in roots and shoots were 69.5%and 20.3%, respectively. These results indicate that Cd is mainly transported into root cells through nonselective cation channels, while Mn is primarily carried into root cells via positive trans-porters. Manganese may inhibit Cd uptake and translocation in rice seedlings by competing ionic channels and carrier proteins.