College of Resources, Sichuan Agricultural University, Chengdu, China.
Sichuan Provincial Academy of Natural Resource and Sciences, Chengdu, China.
J Appl Microbiol. 2019 Mar;126(3):919-930. doi: 10.1111/jam.14165. Epub 2019 Jan 2.
Because the effect of Cd -immobilized microbe on Cd uptake of plants in Cd-contaminated soil remains underexplored, this study focuses on the effect of Cd -immobilized rhizobia on Cd uptake of soybean.
Strain KG2 from soybean nodule was identified as Rhizobium pusense KG2 by phylogenetic analysis. Rhizobium pusense KG2 showed the 120 mg l of minimal lethal concentration for Cd . In 50 and 100 mg l of Cd liquid, approximately 2 × 10 cells removed 56·71 and 22·11% of Cd , respectively. In pot soil containing 50 and 100 mg kg of Cd , strain KG2 caused a 45·9 and 35·3% decrease in soybean root Cd content, respectively. Meanwhile, KG2 improved the root and shoot length, nitrogen content and biomass of soybean plants and superoxide dismutase activity.
The Cd -immobilized rhizobia could inhibit soybean plants to absorb Cd from soil, promote plant growth and improve plant's tolerance against Cd. This study is the first time to report that R. pusense is an effective nodulating rhizobium of legume.
Some Cd -immobilized microbe lowering Cd uptake of plant and promoting plant growth should be considered as an effective strategy for producing safety crops in the Cd-contaminated agricultural soil.
由于 Cd 固定微生物对污染土壤中植物 Cd 吸收的影响尚未得到充分研究，本研究重点关注 Cd 固定根瘤菌对大豆 Cd 吸收的影响。
通过系统发育分析，从大豆根瘤中鉴定出菌株 KG2 为 Rhizobium pusense KG2。Rhizobium pusense KG2 的最小致死浓度 Cd 为 120 mg/L。在 50 和 100 mg/L 的 Cd 液体中，分别有约 2×10 个细胞去除了 56.71%和 22.11%的 Cd。在含 50 和 100 mg/kg Cd 的盆栽土壤中，菌株 KG2 分别使大豆根 Cd 含量降低了 45.9%和 35.3%。同时，KG2 提高了大豆根和茎的长度、氮含量和生物量以及超氧化物歧化酶活性。
Cd 固定根瘤菌可以抑制大豆植株从土壤中吸收 Cd，促进植物生长，提高植物对 Cd 的耐受性。本研究首次报道了 R. pusense 是一种有效的豆科结瘤根瘤菌。
一些降低植物 Cd 吸收并促进植物生长的 Cd 固定微生物应被视为在 Cd 污染农田生产安全作物的有效策略。
