Aims

Nickel (Ni) and zinc (Zn) interactions during their uptake and root-to-shoot translocation and the potential role of histidine therein were studied in different populations of the Ni/Zn hyperaccumulator Noccaea caerulescens and the Ni hyperaccumulator Odontarrhena corsica.

Methods

The effect of exogenous L-histidine supply on Ni and Zn uptake and translocation in N. caerulescens and O. corsica, and xylem loading in shoot-excised root systems of different N. caerulescens populations, were studied under separate and combined exposure.

Results

In O. corsica, Zn inhibited both the translocation and the uptake of Ni, whereas Ni did not significantly affect Zn uptake or translocation. In N. caerulescens, both in intact plants and shoot-excised root systems, Zn usually inhibited the uptake, but not the translocation of Ni, whereas Ni did not affect the uptake, but inhibited the translocation of Zn, though not in two populations with low Zn xylem loading capacity. Exogenous histidine supply did not significantly affect Zn translocation in O. corsica and intact plants of an ultramafic population of N. caerulescens, but enhanced Zn xylem loading in two calamine populations of N. caerulescens and Ni translocation in all of them.

Conclusions

High free L-histidine concentrations in roots might promote Ni hyperaccumulation in obligate Ni hyperaccumulators, such as O. corsica, in nature. The high histidine concentration in roots of N. caerulescens, which is primarily a Zn hyperaccumulator, might not only explain its species-wide conserved capacity to hypertranslocate Ni, but may also contribute to its Zn translocation capacity, at least in non-ultramafic populations.

中文翻译：

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Odontarrhena corsica 和 Noccaea caerulescens 中 Ni 和 Zn 的易位：外源组氨酸和 Ni/Zn 相互作用的影响

宗旨

在 Ni/Zn 超富集植物Noccaea caerulescens和 Ni 超富集植物Odontarrhena corsica 的不同种群中，研究了镍 (Ni) 和锌 (Zn) 在吸收和根到地上部易位过程中的相互作用以及组氨酸在其中的潜在作用。

方法

在单独和联合暴露下研究外源 L-组氨酸供应对N. caerulescens和O. corsica 中Ni 和 Zn 吸收和易位的影响，以及不同N. caerulescens种群的枝条切除根系中木质部负荷的影响。

结果

在O. corsica 中，Zn 抑制了 Ni 的易位和摄取，而 Ni 没有显着影响 Zn 的摄取或易位。在N. caerulescens 中，无论是在完整植株还是在茎部切除的根系中，Zn 通常抑制 Ni 的吸收，但不抑制 Ni 的易位；而 Ni 不影响吸收，但抑制 Zn 的易位，尽管在两个具有低锌木质部负载能力。外源组氨酸供应没有显着影响O. corsica和N. caerulescens超镁铁质种群的完整植株中的Zn 易位，但增加了N. caerulescens 的两个炉甘石种群中的 Zn 木质部负载和所有这些中的 Ni 易位。

结论

根中高浓度的游离 L-组氨酸可能会促进自然界中专性 Ni 超富集植物（如O. corsica）中的Ni 超富集。N. caerulescens根中的高组氨酸浓度，主要是 Zn 超富集植物，可能不仅可以解释其在物种范围内超易位 Ni 的保守能力，而且还可能有助于其 Zn 易位能力，至少在非超铁性种群中如此。