Key Laboratory of Agrometeorology of Jiangsu Province, School of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing, 210044, China; College of Life Sciences, Nanjing Agricultural University, Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture, Nanjing, 210095, PR China.
Key Laboratory of Agrometeorology of Jiangsu Province, School of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing, 210044, China.
Environ Pollut. 2021 Jan 1;268(Pt A):115850. doi: 10.1016/j.envpol.2020.115850. Epub 2020 Oct 27.
Metal-resistant bacteria can reduce Cd accumulation in plants, but mechanisms underlying this effect are poorly understood. In this study, a highly effective Cd-resistant WRS8 strain was obtained from the rhizoshere soil of Triticum aestivum L. Yangmai-13 and identified as Pseudomonas taiwanensis based on 16S rRNA gene sequence analysis. Strain WRS8 was investigated for its effects on Cd availability and wheat tissue Cd contents and the related mechanisms using a hydroponic culture experiment. In strain WRS8-inoculated solution, the Cd concentration reduced and the pH and cell-adsorbed Cd increased with time. Strain WRS8 increased the wheat root and above-ground tissue dry weights by 11-36% compared to the controls. In strain WRS8-inoculated wheat plants, the Cd contents of the roots and above-ground tissues decreased by 78-85% and 88-94% and the Cd bioconcentration and translocation factors decreased by 78-85% and 46-58% at days 3 and 10, respectively, compared with the controls. The root surface-adsorbed Cd contents increased by 99-121% in the WRS8 strain-inoculated wheat plants at days 3 and 10 compared to the controls. Furthermore, strain WRS8 colonized the wheat root surfaces and interiors and reduced the expression levels of the LCT1 and HMA2 genes involved in Cd accumulation and transport in wheat roots by 46% and 30%, respectively, compared to the controls. In the Cd-contaminated soils, strain WRS8 significantly reduced the available Cd content by 20-24% and increased the pH compared to the controls. These findings showed the important role of strain WRS8 in reducing solution and soil Cd availability and suggested that strain WRS8 reduced the wheat tissue Cd accumulation by increasing root surface Cd adsorption and decreasing wheat root Cd uptake and transport-related gene expression and may provide a new and effective wheat rhizobacteria-enhanced approach for reducing wheat Cd uptake in Cd-polluted environments.
耐金属细菌可以减少植物中镉的积累，但这种效应的机制尚不清楚。本研究从冬小麦根际土壤中获得了一株高效镉抗性 WRS8 菌株，并基于 16S rRNA 基因序列分析将其鉴定为假单胞菌。采用水培培养实验研究了 WRS8 菌株对镉有效性和小麦组织镉含量的影响及相关机制。在 WRS8 菌株接种的溶液中，随着时间的推移，镉浓度降低，pH 值和细胞吸附的镉增加。与对照相比，WRS8 菌株增加了小麦根和地上组织的干重 11-36%。在 WRS8 菌株接种的小麦植物中，与对照相比，第 3 天和第 10 天根和地上组织的镉含量分别降低了 78-85%和 88-94%，镉的生物浓缩和转运因子分别降低了 78-85%和 46-58%。与对照相比，WRS8 菌株接种的小麦植物在第 3 天和第 10 天根表面吸附的镉含量分别增加了 99-121%。此外，与对照相比，WRS8 菌株定植于小麦根表面和内部，使参与镉积累和转运的小麦根中 LCT1 和 HMA2 基因的表达水平分别降低了 46%和 30%。在镉污染土壤中，与对照相比，WRS8 菌株显著降低了有效镉含量 20-24%，并提高了 pH 值。这些发现表明 WRS8 菌株在降低溶液和土壤镉有效性方面发挥了重要作用，并表明 WRS8 菌株通过增加根表面镉吸附、降低小麦根镉吸收和转运相关基因表达，降低了小麦组织镉积累，为在镉污染环境中降低小麦镉吸收提供了一种新的有效小麦根际细菌增强方法。
