Hyperaccumulators have exceptional phloem translocation capability for heavy metals. This study aims at quantifying the mobility and accumulation of Ni and Co via the phloem in the model hyperaccumulator Noccaea caerulescens. "Phloem loading capability (PLC)," which is calculated by the "Metal content in phloem sap/Metal content in leaves," was introduced to evaluate the metal phloem mobility, while "Phloem mobility value (PMV)" was used for the normalization of PLC, which sets the PLC of Sr as PMV 0 and that of Rb as 100. The results showed that the PMVs of Ni and Co were 63 and 47, respectively. And the phloem mobility of Rb, Ni, Co, and Sr could be graded as highly mobile, mobile, intermediate, and immobile accordingly. The phloem stream can supply up to 19.1% and 16.0% of the total Ni and Co accumulated in the young leaves, respectively, while for Rb and Sr, the phloem contributes to 29% and 1.4% of the total Rb or Sr, indicating phloem contribution of certain metal is directly linked with its mobility. The results of this study raise the importance of phloem translocation on metal accumulation in shoots and provide insights on the metal cycling process in hyperaccumulators.

中文翻译：

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通过韧皮部中的韧皮部定量定量镍和钴的迁移率和积累，该属在夜蛾科（芥菜科）中。

超级蓄能器对于重金属具有卓越的韧皮部移位能力。这项研究的目的是通过韧皮部模型中的韧皮部量化韧皮部中镍和钴的迁移率和积累。通过“韧皮部汁液中的金属含量/叶片中的金属含量”计算出的“韧皮部负载能力（PLC）”用于评估金属韧皮部的迁移率，而“韧皮部迁移率值（PMV）”用于归一化PLC的设置，将Sr的PLC设置为PMV 0，将Rb的PLC设置为100。结果表明，Ni和Co的PMV分别为63和47。相应地，Rb，Ni，Co和Sr的韧皮部迁移率可分为高度迁移，迁移，中间和不迁移。韧皮部流最多可提供19.1％和16。幼叶中镍和钴的累积总量分别为0％，而对于Rb和Sr，韧皮部占Rb或Sr总量的29％和1.4％，表明某些金属的韧皮部贡献与其迁移率直接相关。这项研究的结果提高了韧皮部易位对枝条中金属积累的重要性，并提供了有关超级蓄积物中金属循环过程的见解。