Rhizoremediation of Diesel-Contaminated Soil with Two Rapeseed Varieties and Petroleum degraders Reveals Different Responses of the Plant Defense Mechanisms

Plant-assisted bioremediation (rhizoremediation) stands out as a potential tool to inactivate or completely remove xenobiotics from the polluted environment. Therefore, it is of key importance to find an adequate combination of plant species and microorganisms that together enhance the clean-up process. To understand the response of plants upon bioaugmentation, the antioxidative and detoxification system was analyzed in high and low erucic acid rapeseed varieties (HEAR and LEAR, respectively), after 8 weeks of their treatment with petroleum degraders and 6000 mg diesel oil/kg dry soil. The oxidative stress was enhanced in LEAR being exposed to sole diesel oil, in comparison with HEAR. However, when LEAR plants were additionally inoculated with bacteria, suppression of total catalase (CAT) and ascorbate peroxidase (APX) activity were observed. Interestingly, glutathione transferase (GST) activity was found in these plants at a much higher level than in HEAR, which correlated with a more efficient diesel removal performed by LEAR in the polluted soil and upon bioaugmentation. A distinct profile of polycyclic aromatic hydrocarbons (PAH) was detected in leaves of these plants. Neither LEAR nor HEAR experienced any changes in the photosynthetic capacity upon diesel pollution and presence of petroleum degraders, which supports the usefulness of rhizoremediation with rapeseed.

植物辅助生物修复（根际修复，rhizoremediation）是一种可从污染环境中灭活或彻底清除异生物质（xenobiotics）的潜在修复技术。因此，筛选能够协同强化污染清除进程的适宜植物-微生物组合，具有核心研究价值。为解析植物在生物强化条件下的响应，本研究以高芥酸油菜品种（HEAR）与低芥酸油菜品种（LEAR）为材料，将其经石油降解菌处理并施加6000 mg柴油/kg干土后培养8周，随后对其抗氧化与解毒系统展开分析。相较于高芥酸油菜，仅暴露于单一柴油污染的低芥酸油菜体内氧化应激水平显著升高。然而，当低芥酸油菜额外接种细菌后，其体内过氧化氢酶（CAT）与抗坏血酸过氧化物酶（APX）的总活性受到显著抑制。值得关注的是，这些接种细菌的低芥酸油菜体内谷胱甘肽转移酶（GST）活性远高于高芥酸油菜，这一现象与其在污染土壤及生物强化条件下更高效的柴油清除效果呈显著正相关。研究还在两类油菜的叶片中检测到了特征性多环芳烃（PAH）谱图。无论是否遭受柴油污染或添加石油降解菌，高、低芥酸油菜的光合能力均未发生明显变化，该结果佐证了油菜根际修复技术的应用价值。