Growth and Antimony Bioconcentration Characteristics of Wild Ramie (Boehmeria nivea) under Sb Stress in Different Valence States

[Objectives] To explore the effects of antimony (Sb) in different valence states on the growth and Sb bioconcentration and transfer of wild ramie (Boehmeria nivea). [Methods] A pot experiment was conducted to study the effects of Sb (III) and Sb (V) stress on plant height, biomass, leaf SPAD value, Sb contents in various organs, Sb bioconcentration and transfer factors, and other indexes. [Results] Both kinds of Sb treatments showed a trend of "first increasing and then decreasing" in plant height as Sb concentration increased. The plant heights in Sb (III) treatments with a concentration lower than 1 000 mg/kg and Sb (V) treatments with concentrations lower than 4 000 mg/kg were significantly higher than that of the control check (CK); and the Sb (III) treatment of the high concentration (4 000 mg/kg) resulted in a significant decrease in plant height, while the 8 000 mg/kg Sb (V) treatment still showed an increase in plant height, indicating that the toxicity of Sb (V) to wild ramie was significantly lower than that of Sb (III). The Sb (III) treatments with a concentration lower than 2 000 mg/kg had little effect on the dry weight of the aboveground part, while the treatment with a higher concentration showed a significant decrease; and the dry weights in various concentrations of Sb (V) treatments showed no significant differences, but they were significantly higher than the CK and corresponding concentration of Sb (III) treatment. Both types of Sb stress could promote the increase of SPAD value in wild ramie leaves, and the performance was significantly higher than the CK. As the concentration of Sb treatment increased, the Sb content in both the aboveground and underground parts showed a significant increase; and the comparison of Sb content under corresponding concentrations of the two types of Sb treatments showed that in the aboveground part, Sb (III) was higher than Sb (V), while in the underground part, the opposite was true. The bioconcentration factor (BF) of Sb decreased with the increase of Sb treatment concentration overall, and the value of Sb (V) was smaller than that of Sb (III), but both kinds of Sb stress were significantly smaller than the CK. The transfer factor (TF) of Sb in wild ramie showed a trend of "increasing first and then decreasing" with the concentration of Sb treatment, and various treatments of Sb (III) were higher than the CK, with significant differences, while among various treatments of Sb (V), except treatment B3, the reduction of which was not significant, other Sb (V) treatments showed significant decreases. Comparing the two types of Sb treatments, the BF and TF values of Sb in wild ramie under Sb (III) treatments were higher than those under Sb (V) treatments, and the TF reached a significant level, indicating that the Sb transport ability of wild ramie under Sb (III) treatments was stronger. [Conclusions] This study provides a theoretical basis for the mining of wild ramie Sb restoration genes and the application of large-scale cultivation in ecological restoration.

【研究目的】探究不同价态锑（Sb）对野生苎麻（Boehmeria nivea）生长、锑生物富集与转运特性的影响。【研究方法】采用盆栽试验，探究三价锑（Sb(III)）与五价锑（Sb(V)）胁迫对野生苎麻株高、生物量、叶片SPAD值、各器官锑含量、锑生物富集系数与转运系数等指标的影响。【研究结果】两种价态的锑胁迫下，野生苎麻株高均随锑浓度升高呈现“先升后降”的变化趋势。其中，三价锑浓度低于1000 mg/kg、五价锑浓度低于4000 mg/kg的处理组株高均显著高于对照（CK）；高浓度4000 mg/kg的三价锑处理会导致株高显著降低，而8000 mg/kg的五价锑处理仍可使株高升高，表明五价锑对野生苎麻的毒性显著低于三价锑。三价锑浓度低于2000 mg/kg的处理对野生苎麻地上部干重无显著影响，而更高浓度的三价锑处理则会导致地上部干重显著降低；各浓度五价锑处理组的地上部干重无显著差异，但均显著高于对照与对应浓度的三价锑处理组。两种价态的锑胁迫均可提升野生苎麻叶片的SPAD值，且处理组SPAD值均显著高于对照。随着锑处理浓度升高，野生苎麻地上部与地下部的锑含量均显著升高；对比两种价态锑处理在对应浓度下的锑含量可知，地上部锑含量表现为三价锑高于五价锑，地下部则恰好相反。锑的生物富集系数（BF）总体随锑处理浓度升高而降低，且五价锑的BF值低于三价锑，但两种价态锑胁迫下的BF值均显著低于对照。野生苎麻的锑转运系数（TF）随锑处理浓度升高呈现“先升后降”的变化趋势；各三价锑处理组的TF值均显著高于对照，而五价锑各处理组中，除B3处理组降幅不显著外，其余五价锑处理组的TF值均显著降低。对比两种价态的锑处理可知，三价锑处理下野生苎麻的锑BF与TF值均高于五价锑处理组，且TF值差异达到显著水平，表明三价锑胁迫下野生苎麻的锑转运能力更强。【研究结论】本研究为野生苎麻锑修复基因的挖掘以及其规模化栽培在生态修复中的应用提供了理论依据。