Economic Crops Research Institute of Jiangxi Province, Nanchang, 330202, Jiangxi, China.
Jiangxi Provincial Research Center for Sericultural Engineering and Technology, Nanchang, 330202, China.
Braz J Microbiol. 2023 Sep;54(3):2297-2305. doi: 10.1007/s42770-023-01090-3. Epub 2023 Aug 18.
Mulberry has a good tolerance to cadmium (Cd) and is considered a candidate plant for phytoremediation. The rhizosphere microbial community plays an important role in phytoremediation. Nevertheless, little information on the rhizosphere microbial community mechanisms in mulberry during the phytoremediation of Cd-contaminated soil is available. In this study, the remediation efficiency of mulberry in pots subjected to three simulated Cd pollution levels and their rhizosphere bacterial communities during the remediation process were analyzed. "Yuesang 11" was used as the test mulberry variety, and three simulated Cd pollution levels were set by adding three concentrations of Cd (Cd5, 5 mg kg; Cd3, 3 mg kg; Cd2, 2 mg kg). The results showed that the elimination rates of Cd in the rhizosphere soil were 81.7%, 85.3%, and 57.9% under the stress of the Cd2, Cd3, and Cd5 conditions, respectively. Meanwhile, 3,082,583 high-quality sequence reads and 976 operational taxonomic units were successfully obtained from the mulberry rhizosphere soil by high-throughput absolute quantification sequencing and further assigned to 11 bacterial phyla and 26 families. Of these, decreased abundances of 19 bacteria at the family level and increased abundances of seven bacteria under Cd stress were revealed by comparative analysis. Based on the alpha diversity indices (Chaol, Shannon and Simpson) and principal component analysis, the rhizosphere bacterial diversity of the Cd5 condition was significantly decreased, but that of the Cd2 and Cd3 conditions was not different from that of soil without Cd (CK). Likewise, redundancy analysis showed that the abundances of Acidobacteria Gp2, Acidobacteria Gp13, and Sphingobacteria were significantly positively associated with the elimination rates of Cd. This study suggested that the mulberry rhizosphere contains a relatively stable bacterial community consisting of diverse Cd-resistant bacteria, providing a scientific basis for remediating heavy-metal polluted soils using mulberry.
桑树对镉（Cd）具有良好的耐受性，被认为是植物修复的候选植物。根际微生物群落在植物修复中起着重要作用。然而，关于桑树在污染土壤的植物修复过程中根际微生物群落机制的信息很少。本研究分析了三种模拟 Cd 污染水平下盆栽桑树的修复效率及其修复过程中的根际细菌群落。“粤桑 11 号”被用作试验桑树品种，通过添加三种浓度的 Cd（Cd5，5mg/kg；Cd3，3mg/kg；Cd2，2mg/kg）设置三种模拟 Cd 污染水平。结果表明，在 Cd2、Cd3 和 Cd5 胁迫下，根际土壤中 Cd 的去除率分别为 81.7%、85.3%和 57.9%。同时，通过高通量绝对定量测序从桑树根际土壤中成功获得了 3082583 条高质量序列和 976 个操作分类单元，并进一步被分配到 11 个细菌门和 26 个科。通过比较分析，发现 19 个细菌科的丰度降低，7 个细菌科的丰度增加。基于α多样性指数（Chao1、Shannon 和 Simpson）和主成分分析，Cd5 条件下的根际细菌多样性显著降低，但 Cd2 和 Cd3 条件下的根际细菌多样性与无 Cd（CK）土壤无差异。同样，冗余分析表明，酸杆菌 Gp2、酸杆菌 Gp13 和鞘脂杆菌的丰度与 Cd 去除率呈显著正相关。本研究表明，桑树根际含有一个相对稳定的细菌群落，由多种耐 Cd 细菌组成，为利用桑树修复重金属污染土壤提供了科学依据。
