Department of Environmental Sciences, Bharathiar University, Coimbatore, 641046, India.
Department of Agronomy, Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Zhejiang Province, China.
J Environ Manage. 2021 Jul 1;289:112553. doi: 10.1016/j.jenvman.2021.112553. Epub 2021 Apr 12.
The co-occurrence of environmental stresses such as heavy metals (HM) and increased atmospheric temperature (IAT) pose serious implications on plant growth and productivity. In this work, we evaluated the role of plant growth-promoting bacteria (PGPB) and its effectiveness on Zea mays growth, stress tolerance and phytoremediation potential in multi-metal (MM) contaminated soils under IAT stress conditions. The PGPB strain TCU11 was isolated from metal contaminated soils and identified as Bacillus cereus. TCU11 was able to resist abiotic stresses such as IAT (45 °C), MM (Pb, Zn, Ni, Cu, and Cd), antibiotics and induced in vitro plant growth promotion (PGP) by producing siderophores (catechol and hydroxymate) and indole 3-acetic acid even in the presence of MM under IAT. Inoculation of TCU11 significantly increased the biomass, chlorophyll, carotenoids, and protein content of Z. mays compared to the respective control under MM, IAT, and MM + IAT stress. A decrease of malondialdehyde and over-accumulation of total phenolics, proline along with the increased activity of superoxide dismutase, catalase and ascorbic peroxidase were observed in TCU11 inoculated plants under stress conditions. These results suggested MM and/or IAT significantly reduced the maize growth, whereas TCU11 inoculation mitigated the combined stress effects on maize performance. Moreover, the inoculation of TCU11 under IAT stress increased the MM (Pb, Zn, Ni, Cu, and Cd) accumulation in plant tissues and also increased the translocation of HM from root to shoot except for Ni. The results of soil HM mobilization further indicates that IAT increased the HM mobilizing activity of TCU11, thus increasing the concentrations of bio-available HM in soil. These results suggested that TCU11 not only alleviates MM and IAT stresses but also enhances the biomass production and HM accumulation in plants. Therefore, TCU11 can be exploited as inoculums for improving the phytoremediation efficiency in MM polluted soils under IAT conditions.
在重金属 (HM) 和大气温度升高 (IAT) 等环境胁迫共同作用下，植物的生长和生产力受到严重影响。在这项工作中，我们评估了植物促生菌 (PGPB) 的作用及其在 IAT 胁迫条件下多金属 (MM) 污染土壤中对玉米生长、胁迫耐受和植物修复潜力的影响。PGPB 菌株 TCU11 从金属污染土壤中分离得到，鉴定为蜡状芽孢杆菌。TCU11 能够抵抗非生物胁迫，如 IAT (45°C)、MM (Pb、Zn、Ni、Cu 和 Cd)、抗生素，并通过产生铁载体 (儿茶酚和羟甲酸盐) 和吲哚 3-乙酸来诱导体外植物生长促进 (PGP)，即使在存在 MM 的情况下也是如此。与 MM、IAT 和 MM+IAT 胁迫下的相应对照相比，TCU11 接种显著增加了玉米的生物量、叶绿素、类胡萝卜素和蛋白质含量。在胁迫条件下，TCU11 接种的植物中观察到丙二醛含量降低，总酚类物质、脯氨酸过度积累，超氧化物歧化酶、过氧化氢酶和抗坏血酸过氧化物酶活性增加。这些结果表明，MM 和/或 IAT 显著降低了玉米的生长，而 TCU11 接种减轻了复合胁迫对玉米性能的影响。此外，在 IAT 胁迫下接种 TCU11 增加了植物组织中 MM (Pb、Zn、Ni、Cu 和 Cd) 的积累，除 Ni 外，还增加了 HM 从根部向地上部的转运。土壤 HM 迁移的结果进一步表明，IAT 增加了 TCU11 的 HM 迁移活性，从而增加了土壤中生物可利用 HM 的浓度。这些结果表明，TCU11 不仅缓解了 MM 和 IAT 胁迫，还增强了植物的生物量生产和 HM 积累。因此，TCU11 可被开发为接种物，以提高 IAT 条件下 MM 污染土壤的植物修复效率。
