PDF(Pubmed)
Abstract：
BACKGROUND: Some subspecies of Dichapetalum gelonioides are the only tropical woody zinc (Zn)-hyperaccumulator plants described so far and the first Zn hyperaccumulators identified to occur exclusively on non-Zn enriched \'normal\' soils. The aim of this study was to investigate Zn cycling in the parent rock-soil-plant interface in the native habitats of hyperaccumulating Dichapetalum gelonioides subspecies (subsp. pilosum and subsp. sumatranum). We measured the Zn isotope ratios (δ66Zn) of Dichapetalum plant material, and associated soil and parent rock materials collected from Sabah (Malaysian Borneo).
RESULTS: We found enrichment in heavy Zn isotopes in the topsoil (δ66Zn 0.13 ‰) relative to deep soil (δ66Zn -0.15 ‰) and bedrock (δ66Zn -0.90 ‰). This finding suggests that both weathering and organic matter influenced the Zn isotope pattern in the soil-plant system, with leaf litter cycling contributing significantly to enriched heavier Zn in topsoil. Within the plant, the roots were enriched in heavy Zn isotopes (δ66Zn ~ 0.60 ‰) compared to mature leaves (δ66Zn ~ 0.30 ‰), which suggests highly expressed membrane transporters in these Dichapetalum subspecies preferentially transporting lighter Zn isotopes during root-to-shoot translocation. The shoots, mature leaves and phloem tissues were enriched in heavy Zn isotopes (δ66Zn 0.34-0.70 ‰) relative to young leaves (δ66Zn 0.25 ‰). Thisindicates that phloem sources are enriched in heavy Zn isotopes relative to phloem sinks, likely because of apoplastic retention and compartmentalization in the Dichapetalum subspecies.
CONCLUSIONS: The findings of this study reveal Zn cycling in the rock-soil-plant continuum within the natural habitat of Zn hyperaccumulating subspecies of Dichapetalum gelonioides from Malaysian Borneo. This study broadens our understanding of the role of a tropical woody Zn hyperaccumulator plant in local Zn cycling, and highlights the important role of leaf litter recycling in the topsoil Zn budget. Within the plant, phloem plays key role in Zn accumulation and redistribution during growth and development. This study provides an improved understanding of the fate and behaviour of Zn in hyperaccumulator soil-plant systems, and these insights may be applied in the biofortification of crops with Zn.
RESULTS: We found enrichment in heavy Zn isotopes in the topsoil (δ66Zn 0.13 ‰) relative to deep soil (δ66Zn -0.15 ‰) and bedrock (δ66Zn -0.90 ‰). This finding suggests that both weathering and organic matter influenced the Zn isotope pattern in the soil-plant system, with leaf litter cycling contributing significantly to enriched heavier Zn in topsoil. Within the plant, the roots were enriched in heavy Zn isotopes (δ66Zn ~ 0.60 ‰) compared to mature leaves (δ66Zn ~ 0.30 ‰), which suggests highly expressed membrane transporters in these Dichapetalum subspecies preferentially transporting lighter Zn isotopes during root-to-shoot translocation. The shoots, mature leaves and phloem tissues were enriched in heavy Zn isotopes (δ66Zn 0.34-0.70 ‰) relative to young leaves (δ66Zn 0.25 ‰). Thisindicates that phloem sources are enriched in heavy Zn isotopes relative to phloem sinks, likely because of apoplastic retention and compartmentalization in the Dichapetalum subspecies.
CONCLUSIONS: The findings of this study reveal Zn cycling in the rock-soil-plant continuum within the natural habitat of Zn hyperaccumulating subspecies of Dichapetalum gelonioides from Malaysian Borneo. This study broadens our understanding of the role of a tropical woody Zn hyperaccumulator plant in local Zn cycling, and highlights the important role of leaf litter recycling in the topsoil Zn budget. Within the plant, phloem plays key role in Zn accumulation and redistribution during growth and development. This study provides an improved understanding of the fate and behaviour of Zn in hyperaccumulator soil-plant systems, and these insights may be applied in the biofortification of crops with Zn.
摘要：
背景：Dichapetalumgelonioides的一些亚种是迄今为止描述的唯一的热带木本锌（Zn）高积累植物，并且第一个锌高积累植物被确定仅发生在非锌富集的“正常”土壤上。这项研究的目的是研究高积累的双hapetalumgelonioides亚种（亚种。pilosum和subsp.sumatranum）。我们测量了Dichapetalum植物材料的Zn同位素比率（δ66Zn），以及从沙巴（马来西亚婆罗洲）收集的相关土壤和母岩材料。
结果：我们发现，相对于深层土壤（δ66Zn-0.15‰）和基岩（δ66Zn-0.90‰），表层土壤（δ66Zn-0.13‰）中的重Zn同位素富集。这一发现表明，风化和有机质都影响了土壤-植物系统中的Zn同位素模式，凋落物循环显着促进表层土壤中重锌的富集。在植物内部,与成熟叶（δ66Zn〜0.30‰）相比，根部富含重Zn同位素（δ66Zn〜0.60‰），这表明这些双hapetalum亚种中高表达的膜转运蛋白在根到茎的易位过程中优先转运较轻的Zn同位素。拍摄，相对于幼叶（δ66Zn0.25‰），成熟叶和韧皮部组织富含重Zn同位素（δ66Zn0.34-0.70‰）。这表明韧皮部来源相对于韧皮部汇富含重Zn同位素，可能是由于二甲鱼亚种的质质保留和区隔。
结论：这项研究的结果揭示了来自马来西亚婆罗洲的Dichapetalumgelonioides的Zn高积累亚种的自然栖息地内的岩石-土壤-植物连续体中的Zn循环。这项研究扩大了我们对热带木本Zn超富集植物在当地Zn循环中的作用的理解，并强调了凋落物回收在表土Zn收支中的重要作用。在植物内部,韧皮部在生长发育过程中锌的积累和再分配中起着关键作用。这项研究提供了对高积累土壤-植物系统中Zn的命运和行为的更好理解。这些见解可应用于锌对作物的生物强化。
结果：我们发现，相对于深层土壤（δ66Zn-0.15‰）和基岩（δ66Zn-0.90‰），表层土壤（δ66Zn-0.13‰）中的重Zn同位素富集。这一发现表明，风化和有机质都影响了土壤-植物系统中的Zn同位素模式，凋落物循环显着促进表层土壤中重锌的富集。在植物内部,与成熟叶（δ66Zn〜0.30‰）相比，根部富含重Zn同位素（δ66Zn〜0.60‰），这表明这些双hapetalum亚种中高表达的膜转运蛋白在根到茎的易位过程中优先转运较轻的Zn同位素。拍摄，相对于幼叶（δ66Zn0.25‰），成熟叶和韧皮部组织富含重Zn同位素（δ66Zn0.34-0.70‰）。这表明韧皮部来源相对于韧皮部汇富含重Zn同位素，可能是由于二甲鱼亚种的质质保留和区隔。
结论：这项研究的结果揭示了来自马来西亚婆罗洲的Dichapetalumgelonioides的Zn高积累亚种的自然栖息地内的岩石-土壤-植物连续体中的Zn循环。这项研究扩大了我们对热带木本Zn超富集植物在当地Zn循环中的作用的理解，并强调了凋落物回收在表土Zn收支中的重要作用。在植物内部,韧皮部在生长发育过程中锌的积累和再分配中起着关键作用。这项研究提供了对高积累土壤-植物系统中Zn的命运和行为的更好理解。这些见解可应用于锌对作物的生物强化。
