Nishida Sho, Tanikawa Ryoji, Ishida Shota, Yoshida Junko, Mizuno Takafumi, Nakanishi Hiromi, Furuta Naoki
Laboratory of Plant Nutrition, Faculty of Agriculture, Saga University, Saga, Japan.
Laboratory of Environmental Chemistry, Faculty of Science and Engineering, Chuo University, Tokyo, Japan.
Front Plant Sci. 2020 Jun 3;11:610. doi: 10.3389/fpls.2020.00610. eCollection 2020.
A number of metal hyperaccumulator plants, including nickel (Ni) hyperaccumulators, have been identified in the genus . The ability to accumulate Ni in shoots varies widely among species and ecotypes in this genus; however, little is known about the molecular mechanisms underlying this intra- and inter-specific variation. Here, in hydroponic culture, we compared Ni accumulation patterns between , which originated in Ni-enriched serpentine soils in Mt. Yubari (Hokkaido, Japan), and ecotype Ganges, which originated in zinc/lead-mine soils in Southern France. Both species showed extremely high Ni tolerance compared with that of the non-accumulator . But, following treatment with 200 μM Ni, showed leaf chlorosis, whereas did not show any stress symptoms. Shoot Ni concentration was higher in than in ; this difference was due to higher efficiency of root-to-shoot Ni translocation in than . It is known that the vacuole Ni transporter IREG2 suppresses Ni translocation from roots to shoots by sequestering Ni in the root vacuoles. The expression level of the gene in the roots of was 10-fold that in the roots of . Moreover, the copy number of per genome was higher in than in , suggesting that expression is elevated by gene multiplication in . The heterologous expression of of and in yeast and confirmed that both genes encode functional vacuole Ni transporters. Taking these results together, we hypothesize that the elevation of expression by gene multiplication causes the lower root-to-shoot Ni translocation in .
在该属中已鉴定出多种金属超积累植物，包括镍（Ni）超积累植物。该属中不同物种和生态型在地上部积累镍的能力差异很大；然而，关于这种种内和种间变异背后的分子机制却知之甚少。在此，我们在水培条件下，比较了原产于日本北海道夕张山富含镍的蛇纹石土壤中的[物种名称1]和原产于法国南部锌/铅矿土壤中的[物种名称2]生态型恒河之间的镍积累模式。与非积累植物相比，这两个[物种名称1和2]物种都表现出极高的镍耐受性。但是，用200μM镍处理后，[物种名称1]出现叶片黄化，而[物种名称2]未表现出任何胁迫症状。[物种名称1]地上部的镍浓度高于[物种名称2]；这种差异是由于[物种名称1]从根到地上部的镍转运效率高于[物种名称2]。已知液泡镍转运体IREG2通过将镍隔离在根液泡中来抑制镍从根向地上部的转运。[物种名称1]根中[基因名称]的表达水平是[物种名称2]根中的10倍。此外，[物种名称1]每个基因组中[基因名称]的拷贝数高于[物种名称2]，这表明[物种名称1]中[基因名称]的表达因基因倍增而升高。将[物种名称1和2]的[基因名称]在酵母中进行异源表达证实，这两个[基因名称]都编码功能性液泡镍转运体。综合这些结果，我们推测基因倍增导致的[基因名称]表达升高导致了[物种名称1]中根到地上部的镍转运较低。
