Abstract：
Woody plants possess great potential for phytoremediation of heavy metal-contaminated soil. A pot trial was conducted to study growth, physiological response, and Cd and Pb uptake and distribution in black locust (Robinia pseudoacacia L.), as well as the rhizosphere bacterial communities in Cd and Pb co-contaminated soil. The results showed that R. pseudoacacia L. had strong physiological regulation ability in response to Cd and Pb stress in contaminated soil. The total chlorophyll, malondialdehyde (MDA), soluble protein, and sulfhydryl contents, as well as antioxidant enzymes (superoxide dismutase, peroxidase, catalase) activities in R. pseudoacacia L. leaves under the 40 mg·kg-1 Cd and 1000 mg·kg-1 Pb co-contaminated soil were slightly altered. Cd uptake in R. pseudoacacia L. roots and stems increased, while the Pb content in the shoots of R. pseudoacacia L. under the combined Cd and Pb treatments decreased in relative to that in the single Pb treatments. The bacterial α-diversity indices (e.g., Sobs, Shannon, Simpson, Ace, and Chao) of R. pseudoacacia L. rhizosphere soil under Cd and Pb stress were changed slightly relative to the CK treatment. However, Cd and Pb stress could significantly (p < 0.05) alter the rhizosphere soil microbial communities. According to heat map and LEfSe (Linear discriminant analysis Effect Size) analysis, Bacillus, Sphingomonas, Terrabacter, Roseiflexaceae, Paenibacillus, and Myxococcaceae at the genus level were notably (p < 0.05) accumulated in the Cd- and/or Pb-contaminated soil. Furthermore, the MDA content was notably (p < 0.05) negatively correlated with the relative abundances of Isosphaeraceae, Gaiellales, and Gemmatimonas. The total biomass of R. pseudoacacia L. was positively (p < 0.05) correlated with the relative abundances of Xanthobacteraceae and Vicinamibacreraceae. Network analysis showed that Cd and Pb combined stress might enhance the modularization of bacterial networks in the R. pseudoacacia L. rhizosphere soil. Thus, the assembly of the soil bacterial communities in R. pseudoacacia L. rhizosphere may improve the tolerance of plants in response to Cd and/or Pb stress.
摘要：
木本植物在重金属污染土壤的植物修复中具有巨大的潜力。进行了盆栽试验以研究生长，生理反应，刺槐（刺槐）中Cd和Pb的吸收和分布，以及Cd和Pb共污染土壤中的根际细菌群落。结果表明,刺槐对污染土壤中Cd、Pb胁迫具有较强的生理调控能力。总叶绿素,丙二醛（MDA），可溶性蛋白质，和巯基含量，以及抗氧化酶(超氧化物歧化酶，过氧化物酶,过氧化氢酶）活性在40mg·kg-1Cd和1000mg·kg-1Pb共污染土壤下的刺槐叶片中略有变化。刺槐根和茎中Cd的吸收增加，而在Cd和Pb联合处理下，刺槐芽中的Pb含量相对于单一Pb处理降低。细菌α多样性指数(例如，Sobs,香农,辛普森,Ace,和Chao）在Cd和Pb胁迫下的根际土壤相对于CK处理略有变化。然而,Cd和Pb胁迫可显著改变根际土壤微生物群落(p<0.05)。根据热图和LEfSe(线性判别分析效应大小)分析，芽孢杆菌,鞘氨醇单胞菌,Terrabacter,玫瑰科,拟芽孢杆菌,在镉和/或铅污染的土壤中，明显（p<0.05）积累了属水平的粘球菌科。此外，丙二醛含量与异sphaeraceae的相对丰度呈显著负相关(p<0.05),盖勒莱斯,和Gemmatatimonas.刺槐的总生物量与黄杆菌科和维多利亚杆菌科的相对丰度呈正相关（p<0.05）。网络分析表明，Cd和Pb联合胁迫可能会增强刺槐根际土壤细菌网络的模块化。因此，刺槐根际土壤细菌群落的组装可能会提高植物对Cd和/或Pb胁迫的耐受性。
