Abstract

Phytoextraction of toxic metals from soil by hyperaccumulating plants is an increasingly common and effective method of bioremediation. This process is often enhanced through the addition of specific plant hormones (phytohormones) that can stimulate growth and metal uptake. However, further gains in efficiency could increase the broad application of phytoextraction and those efficiencies might be gained belowground via root growth and potentially improved foraging via increased mycorrhizal colonization. We conducted an experiment to test if additions of strigolactones, an important class of general phytohormones known to stimulate root growth and mycorrhizal fungal growth and metabolism, increased soil lead (Pb) uptake by dwarf sunflower (Helianthus annuus) relative to other commonly used phytohormones. Sunflowers were grown in lead-amended soil with additions of auxin, cytokinin, gibberellin, and strigolactone, and then Pb accumulation in plant tissue was quantified after 4 weeks. We found that strigolactone-treated sunflowers had significantly elevated Pb concentrations in their above and belowground tissues (∼2.5×) compared to the control, auxin, and gibberellin treatments, and that the effect of all hormones combined was roughly equal to the strigolactone alone treatment. These results suggest that strigolactones can significantly increase the efficiency of the phytoextraction process on relatively short time scales. Future studies need to identify specific physiological and fungal responses to strigolactone treatments as well how these responses might translate to different types and forms of metals and other plant species.

摘要

通过超积累植物从土壤中提取有毒金属是一种越来越普遍和有效的生物修复方法。这个过程通常通过添加可以刺激生长和金属吸收的特定植物激素（植物激素）来增强。然而，效率的进一步提高可以增加植物提取的广泛应用，这些效率可以通过根系生长在地下获得，并可能通过增加菌根定植来改善觅食。我们进行了一项实验，以测试添加独脚金内酯（一种重要的一类重要的通用植物激素，已知可刺激根生长和菌根真菌生长和代谢）是否会增加矮向日葵（Helianthus annuus）对土壤铅 (Pb) 的吸收) 相对于其他常用的植物激素。向日葵在添加了生长素、细胞分裂素、赤霉素和独脚金内酯的铅改良土壤中生长，然后在 4 周后量化植物组织中的 Pb 积累。我们发现，与对照、生长素和赤霉素处理相比，独脚金内酯处理的向日葵的地上和地下组织中的 Pb 浓度显着升高（~2.5 倍），并且所有激素组合的效果与独脚金内酯单独处理的效果大致相同. 这些结果表明独脚金内酯可以在相对较短的时间内显着提高植物提取过程的效率。