Zhang Yong, Zhao Shangjun, Liu Sijia, Peng Jing, Zhang Hanchao, Zhao Qiming, Zheng Luqing, Chen Yahua, Shen Zhenguo, Xu Xihui, Chen Chen
College of Life Sciences, Nanjing Agricultural University, Nanjing, China.
Quzhou Academy of Agriculture and Forestry Sciences, Quzhou Municipal Bureau of Agriculture and Rural Affairs, Quzhou, China.
Front Plant Sci. 2022 Jun 2;13:912350. doi: 10.3389/fpls.2022.912350. eCollection 2022.
Heavy metals (HMs) have become a major environmental pollutant threatening ecosystems and human health. Although hyperaccumulators provide a viable alternative for the bioremediation of HMs, the potential of phytoremediation is often limited by the small biomass and slow growth rate of hyperaccumulators and HM toxicity to plants. Here, plant growth-promoting bacteria (PGPB)-assisted phytoremediation was used to enhance the phytoremediation of HM-contaminated soils. A PGPB with HM-tolerant (HMT-PGPB), sp. PGP15 was isolated from the rhizosphere of a cadmium (Cd) hyperaccumulator, . Pot experiments demonstrated that inoculation with strain PGP15 could significantly increase the growth of . More importantly, strain PGP15 markedly improved Cd accumulation in while alleviating Cd-induced stress in . Specifically, PGP15 inoculation significantly decreased the contents of HO, MDA, and in , while the activities (per gram plant fresh weight) of SOD, APX, and CAT were significantly increased in the PGP15-inoculated plants compared with the control sample. These results suggested that the interactions between strain PGP15 and could overcome the limits of phytoremediation alone and highlighted the promising application potential of the PGPB-hyperaccumulator collaborative pattern in the bioremediation of HM-contaminated soils. Furthermore, the PGP15 genome was sequenced and compared with other strains to explore the mechanisms underlying plant growth promotion by HMT-PGPB. The results showed that core genes that define the fundamental metabolic capabilities of strain PGP15 might not be necessary for plant growth promotion. Meanwhile, PGP15-specific genes, including many transposable elements, played a crucial role in the adaptive evolution of HM resistance. Overall, our results improve the understanding of interactions between HMT-PGPB and plants and facilitate the application of HMT-PGPB in the phytoremediation of HM-contaminated soils.
重金属已成为威胁生态系统和人类健康的主要环境污染物。尽管超积累植物为重金属生物修复提供了一种可行的替代方案，但植物修复的潜力常常受到超积累植物生物量小、生长速率慢以及重金属对植物毒性的限制。在此，利用植物促生细菌（PGPB）辅助植物修复来增强对重金属污染土壤的植物修复效果。从镉（Cd）超积累植物的根际分离出一株具有重金属耐受性的PGPB，即菌株PGP15。盆栽实验表明，接种菌株PGP15能显著促进[植物名称未明确]的生长。更重要的是，菌株PGP15显著提高了[植物名称未明确]对镉的积累，同时减轻了镉对[植物名称未明确]的胁迫。具体而言，接种PGP15显著降低了[植物名称未明确]中过氧化氢（HO）、丙二醛（MDA）和[物质名称未明确]的含量，而与对照样品相比，接种PGP15的植物中每克植物鲜重的超氧化物歧化酶（SOD）、抗坏血酸过氧化物酶（APX）和过氧化氢酶（CAT）活性显著增加。这些结果表明，菌株PGP15与[植物名称未明确]之间的相互作用可以克服单独植物修复的局限性，并突出了PGPB - 超积累植物协同模式在重金属污染土壤生物修复中的应用潜力。此外，对PGP15基因组进行了测序并与其他菌株进行比较，以探索HMT - PGPB促进植物生长的潜在机制。结果表明，定义菌株PGP15基本代谢能力的核心基因可能并非促进植物生长所必需。同时，PGP15特异性基因，包括许多转座元件，在重金属抗性的适应性进化中发挥了关键作用。总体而言，我们的研究结果增进了对HMT - PGPB与植物之间相互作用的理解，并促进了HMT - PGPB在重金属污染土壤植物修复中的应用。
