Centre for Mined Land Rehabilitation, Sustainable Minerals Institute, The University of Queensland, St Lucia 4072, Australia.
Department of Botany and Zoology, Stellenbosch University, Matieland 7602, South Africa.
Metallomics. 2022 May 13;14(5). doi: 10.1093/mtomcs/mfac020.
Globally, the majority of Ni hyperaccumulator plants occur on ultramafic soils in tropical regions, and the genus Phyllanthus, from the Phyllanthaceae family, is globally the most represented taxonomical group. Two species from Sabah (Malaysia) are remarkable because Phyllanthus balgooyi can attain >16 wt% of Ni in its phloem exudate, while Phyllanthus rufuschaneyi reaches foliar concentrations of up to 3.5 wt% Ni, which are amongst the most extreme concentrations of Ni in any plant tissue. Synchrotron X-ray fluorescence microscopy, nuclear microbe (micro-PIXE+BS) and (cryo) scanning electron microscopy with energy dispersive spectroscopy were used to spatially resolve the elemental distribution in the plant organs of P. balgooyi and P. rufuschaneyi. The results show that P. balgooyi has extraordinary enrichment of Ni in the (secondary) veins of the leaves, whereas in contrast, in P. rufuschaneyi Ni occurs in interveinal areas. In the roots and stems, Ni is localized mainly in the cortex and phloem but is much lower in the xylem. The findings of this study show that, even within the same genus, the distribution of nickel and other elements, and inferred processes involved with metal hyperaccumulation, can differ substantially between species.
在全球范围内，大多数镍超积累植物生长在热带地区的超镁铁质土壤上，叶下珠科（Phyllanthaceae）的叶下珠属（Phyllanthus）是全球分布最广的分类群。来自马来西亚沙巴的两个物种很引人注目，因为巴尔果油叶下珠（Phyllanthus balgooyi）可以在韧皮部渗出物中达到超过 16wt%的镍，而糙毛叶下珠（Phyllanthus rufuschaneyi）的叶片中镍的浓度高达 3.5wt%，这是任何植物组织中镍浓度最高的物种之一。同步辐射 X 射线荧光显微镜、核微探针（micro-PIXE+BS）和（冷冻）扫描电子显微镜与能量色散光谱联用，用于空间解析 P. balgooyi 和 P. rufuschaneyi 植物器官中的元素分布。结果表明，巴尔果油叶下珠的（次生）叶脉中镍的含量非常高，而相反，糙毛叶下珠中镍存在于叶脉之间的区域。在根和茎中，镍主要定位于皮层和韧皮部，但木质部中的镍含量要低得多。本研究的结果表明，即使在同一属内，镍和其他元素的分布以及与金属超积累相关的推断过程，在不同物种之间也可能存在很大差异。
