Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, 15260, USA,
J Chem Ecol. 2014 Feb;40(2):128-35. doi: 10.1007/s10886-014-0380-x. Epub 2014 Jan 30.
Hyperaccumulation is the phenomenon whereby plants take up and sequester in high concentrations elements that generally are excluded from above-ground tissues. It largely is unknown whether the metals taken up by these plants are transferred to floral rewards (i.e., nectar and pollen) and, if so, whether floral visitation is affected. We grew Streptanthus polygaloides, a nickel (Ni) hyperaccumulator, in short-term Ni supplemented soils and control soils to determine whether Ni is accumulated in floral rewards and whether floral visitation is affected by growth in Ni-rich soils. We found that while supplementation of soils with Ni did not alter floral morphology or reward quantity (i.e., anther size or nectar volume), Ni did accumulate in the nectar and pollen-filled anthers-providing the first demonstration that Ni is accumulated in pollinator rewards. Further, S. polygaloides grown in Ni-supplemented soils received fewer visits per flower per hour from both bees and flies (both naïve to Ni-rich floral resources in the study area) relative to plants grown in control soils, although the probability a plant was visited initially was unaffected by Ni treatment. Our findings show that while Ni-rich floral rewards decrease floral visitation, floral visitors are not completely deterred, so some floral visitors may collect and ingest potentially toxic resources from metal-hyperaccumulating plants. In addition to broadening our understanding of the effects of metal accumulation on ecological interactions in natural populations, these results have implications for the use of insect-pollinated plants in phytoremediation.
超积累是指植物吸收并将通常排除在上部组织中的元素高度浓缩的现象。这些植物吸收的金属是否转移到花的奖励（即花蜜和花粉），以及如果是这样，是否会影响花卉访问，在很大程度上尚不清楚。我们在短期补充镍（Ni）的土壤和对照土壤中种植了镍超积累植物 Streptanthus polygaloides，以确定 Ni 是否积累在花的奖励中，以及在富含 Ni 的土壤中生长是否会影响花卉访问。我们发现，尽管土壤中补充 Ni 不会改变花的形态或奖励数量（即花药大小或花蜜量），但 Ni 确实会积累在充满花蜜和花粉的花药中——这是首次证明 Ni 积累在传粉者的奖励中。此外，与在对照土壤中生长的植物相比，在 Ni 补充土壤中生长的 S. polygaloides 每小时每朵花从蜜蜂和苍蝇（在研究区域对富含 Ni 的花卉资源都不熟悉）获得的访问次数更少，尽管 Ni 处理对植物最初被访问的概率没有影响。我们的研究结果表明，尽管富含 Ni 的花的奖励会降低花的访问量，但花的访客并没有完全被阻止，因此一些花的访客可能会从金属超积累植物中收集和摄入潜在有毒资源。除了拓宽我们对金属积累对自然种群中生态相互作用的影响的理解外，这些结果还对利用虫媒授粉植物进行植物修复具有重要意义。
