Background and aims

Neptunia amplexicaulis, endemic to Central Queensland (Australia), is one of the strongest selenium (Se) hyperaccumulators known globally, capable of accumulating up to 13 600 µg Se g^− 1 in its leaves. This work aimed to elucidate root foraging in response to Se in N. amplexicaulis applied in two different chemical forms and concentrations compared to the sympatric non-accumulator N. gracilis.

Methods

Neptunia amplexicaulis and N. gracilis seeds were germinated and transplanted into rhizotrons filled with half control and half Se-dosed soils with low (5 µg Se g^− 1) or high (30 µg Se g^− 1) levels of Se in soluble (Na₂SeO₄) or insoluble (CaSeO₃) form. After 3 weeks, the root density in the two areas of the rhizotrons was measured and plants were removed from the soil to determine biomass and for chemical analysis of Se and other elements.

Results

Major changes were observed in the low Se dosed side in Na₂SeO₄ form, and in the high Se dosed side in CaSeO₃ form in N. amplexicaulis roots: a higher density, Se concentration, Se:S ratio, and a tendency to increase the biomass. In contrast, a reduction in the root density with 30 µg Se g^− 1 in respose to the CaSeO₃ form was observed in N. gracilis.

Conclusions

Neptunia amplexicaulis preferentially foraged in Se soluble enriched soil, which may be beneficial for the plant given the increase in the root biomass at low Se dosed soil. In contrast, a reduction in the root density in N. gracilis indicated avoidance of soils enriched with high insoluble form of Se.

中文翻译：

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澳大利亚高蓄积双歧夜蛾和非蓄积性小夜蛾的根觅食和硒吸收

背景和目标

Neptunia amplexicaulis是昆士兰中部地区（澳大利亚）特有的，是全球已知最强的硒（Se）超积累物之一，其叶片中的积累量高达13 600 µg Se g ^-1。这项工作旨在阐明与同形非蓄积轻链猪笼草相比，以两种不同的化学形式和浓度施用的双歧猪笼草对硒的根觅食。

方法

Neptunia amplexicaulis和N. gracilis种子发芽并移植到充满半对照和一半Se剂量的土壤的根际土壤中，土壤中的可溶性（Na ）硒含量低（5 µg Se g ^{− 1}）或高（30 µg Se g ^{− 1}）₂的SeO ₄）或不溶于（CaSeO ₃）的形式。3周后，测量了根管的两个区域的根系密度，并从土壤中移出了植物以测定生物量并进行硒和其他元素的化学分析。

结果

在低硒钠给药侧观察大的变化₂的SeO ₄形式，并且在高硒CaSeO给药侧₃形式中N.抱茎根：较高的密度，Se的浓度，硒：S比，并趋向于增加生物量。相比之下，在细线猪笼草中观察到以CaSeO ₃形式存在的根密度降低了30 µg Se g ^-1。

结论

Neptunia酒店抱茎优先地觅食硒富集的可溶性土壤，其可以是给定在低硒的根生物量的增加的植物有益给药土壤。相比之下，细叶猪笼草根系密度的降低表明避免了土壤中富含高不溶形式的硒。