MOE Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University , Hangzhou 310058, China.
School of Marine Sciences, Ningbo University , Ningbo 315211, China.
Environ Sci Technol. 2017 May 16;51(10):5675-5684. doi: 10.1021/acs.est.6b06531. Epub 2017 May 3.
Understanding the strategies that the roots of hyperaccumulating plants use to extract heavy metals from soils is important for optimizing phytoremediation. The rhizosphere characteristics of Sedum alfredii, a hyperaccumulator, were investigated 6 months after it had been planted in weathered field soils contaminated with 5.8 μg of Cd g, 1985.1 μg of Zn g, 667.5 μg of Pb g, and 698.8 μg of Cu g. In contrast with the non-hyperaccumulating ecotype (NHE), the hyperaccumulating ecotype (HE) of S. alfredii was more tolerant to the metals, and higher levels of Cd and Zn accumulated. The HE was characterized by a unique rhizosphere, including extensive root systems, a reduced soil pH, a higher metal bioavailability, and increased rhizomicrobial activity. The bioavailability of metals was significantly correlated with the HE's unique bacterial communities (P < 0.005). The HE harbored abundant Streptomyces (9.43%, family Streptomycetaceae), Kribbella (1.08%, family Nocardioidaceae), and an unclassified genus (1.09%, family Nocardioidaceae) in its rhizosphere, a composition that differed from that of the NHE. PICRUSt analysis predicted high relative abundances of imputed functional profiles in the HE rhizosphere related to membrane transport and amino acid metabolism. This study reveals the rhizosphere characteristics, particularly the unique bacterial rhizobiome of a hyperaccumulator, that might provide a new approach to facilitating heavy metal phytoextraction.
了解超积累植物根系从土壤中提取重金属的策略对于优化植物修复至关重要。研究了超积累植物Sedum alfredii 在被 5.8μg Cd g、1985.1μg Zn g、667.5μg Pb g 和 698.8μg Cu g 污染的风化田间土壤中种植 6 个月后的根际特征。与非超积累生态型（NHE）相比，超积累生态型（HE）的 S. alfredii 对金属的耐受性更强，并且积累了更高水平的 Cd 和 Zn。HE 的特点是具有独特的根际，包括广泛的根系、降低的土壤 pH 值、更高的金属生物利用度和增加的根际微生物活性。金属的生物利用度与 HE 独特的细菌群落显著相关（P<0.005）。HE 在其根际中含有丰富的链霉菌（9.43%，链霉菌科）、Kribbella（1.08%，诺卡氏菌科）和一个未分类的属（1.09%，诺卡氏菌科），其组成与 NHE 不同。PICRUSt 分析预测，HE 根际中与膜转运和氨基酸代谢相关的推测功能谱的相对丰度较高。本研究揭示了超积累植物根际的特征，特别是独特的细菌根际微生物群落，这可能为促进重金属植物提取提供一种新方法。
