es6b06531_si_001.pdf (2.2 MB)
Unique Rhizosphere Microcharacteristics Facilitate Phytoextraction of Multiple Metals in Soil by the Hyperaccumulating Plant Sedum alfredii
journal contribution
posted on 2017-04-24, 00:00 authored by Dandi Hou, Kai Wang, Ting Liu, Haixin Wang, Zhi Lin, Jie Qian, Lingli Lu, Shengke TianUnderstanding
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–1, 1985.1 μg of Zn g–1, 667.5 μg of Pb g–1, and
698.8 μg of Cu g–1. 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.