Danish Mohammad, Shahid Mohammad, Zeyad Mohammad Tarique, Bukhari Najat A, Al-Khattaf Fatimah S, Hatamleh Ashraf Atef, Ali Sajad
Section of Plant Pathology and Nematology, Department of Botany, Aligarh Muslim University, Aligarh202002, Uttar Pradesh, India.
Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh 202002, Uttar Pradesh, India.
ACS Omega. 2022 Apr 17;7(16):13878-13893. doi: 10.1021/acsomega.2c00262. eCollection 2022 Apr 26.
Discharge of nanoparticles (NPs) into aquatic and terrestrial ecosystems during manufacturing processes and from various commercial goods has become a significant ecotoxicological concern. After reaching soil systems, NPs cause deleterious effects on soil fertility, microbial activity, and crop productivity. Taking into consideration the medicinal importance of (L.) (ashwagandha), the present study assessed the potential hazards of silver nanoparticles (Ag-NPs) and the toxicity amelioration by a metal-tolerant plant growth-promoting rhizobacterium (PGPR). BZ-13 (NCBI accession number MZ950923) recovered from metal-polluted rhizosphere soil, tolerated an exceptionally high level of Ag-NPs. The growth-regulating substances synthesized by were increased with increasing concentrations (0-1000 μg mL) of Ag-NPs. Also, strain BZ-13 had the ability to form biofilm, produce alginate and exopolysaccharides (EPSs), as well maintain swimming and swarming motilities in the presence of Ag-NPs. Soil application of varying concentrations of Ag-NPs resulted in a dose-related reduction in growth and biochemical features of ashwagandha. In contrast, following soil inoculation, relieved the Ag-NPs-induced phytotoxicity and improved plant productivity. Root, shoot length, dry biomass, and leaf area increased by 13, 17, 37, 25%, respectively, when was applied with 25 mg/kg Ag-NPs when compared to noninoculated controls. Furthermore, the soil plant analysis development (SPAD) index, photosystem efficiency (Fv/Fm), PS II quantum yield (FPS II), photochemical quenching (qP), non-photochemical quenching (NpQ), and total chlorophyll and carotenoid content of BZ-13-inoculated plants in the presence of 25 mg Ag-NPs/kg increased by 33, 29, 41, 47, 35, 26, and 25%, respectively, when compared to noninoculated controls that were exposed to the same amounts of NPs. In addition, a significant ( ≤ 0.05) increase in 48, 18, 21, and 19% in withaferin-A (alkaloids), flavonoids, phenols, and tannin content, respectively, was recorded when plants were detached from bacterized and Ag-NP-treated plants. Leaf gas exchange parameters were also modulated in the case of inoculated plants. Furthermore, bacterial inoculation significantly decreased proline, lipid peroxidation, antioxidant enzymes, and Ag-NP's absorption and build-up in phyto-organs. In conclusion, soil inoculation with may possibly be used as an alternative to protect plants in soil contaminated with nanoparticles. Therefore, phytohormone and other biomolecule-synthesizing and NP-tolerant PGPR strains like might serve as an agronomically significant and cost-effective remediation agent for augmenting the yield and productivity of medicinally important plants like ashwagandha raised in soil contaminated with nanoparticles in general and Ag-NPs in particular.
在制造过程中以及从各种商业产品中向水生和陆地生态系统排放纳米颗粒（NPs）已成为一个重大的生态毒理学问题。纳米颗粒进入土壤系统后，会对土壤肥力、微生物活性和作物生产力产生有害影响。考虑到印度人参（Withania somnifera (L.)）的药用价值，本研究评估了银纳米颗粒（Ag-NPs）的潜在危害以及耐金属的植物促生根际细菌（PGPR）对其毒性的改善作用。从金属污染的根际土壤中分离出的BZ-13（NCBI登录号MZ950923）能够耐受极高水平的Ag-NPs。随着Ag-NPs浓度（0 - 1000 μg/mL）的增加，BZ-13合成的生长调节物质也随之增加。此外，菌株BZ-13具有形成生物膜、产生藻酸盐和胞外多糖（EPSs）的能力，并且在存在Ag-NPs的情况下仍能保持游动和群体运动能力。土壤中施用不同浓度的Ag-NPs会导致印度人参的生长和生化特性出现剂量相关的降低。相比之下，土壤接种BZ-13后，减轻了Ag-NPs诱导的植物毒性并提高了植物生产力。与未接种的对照相比，当BZ-13与25 mg/kg Ag-NPs一起施用时，根长、茎长、干生物量和叶面积分别增加了13%、17%、37%和25%。此外，在存在25 mg Ag-NPs/kg的情况下，接种BZ-13的植物的土壤植物分析发展（SPAD）指数、光系统效率（Fv/Fm）、PS II量子产率（FPS II）、光化学猝灭（qP）、非光化学猝灭（NpQ）以及总叶绿素和类胡萝卜素含量，与暴露于相同量纳米颗粒的未接种对照相比，分别增加了33%、29%、41%、47%、35%、26%和25%。此外，当从接种细菌和Ag-NP处理的植物上分离叶片时，记录到含Withaferin-A（生物碱）、黄酮类、酚类和单宁的含量分别显著增加（P≤0.05）48%、18%、21%和19%。接种植物的叶片气体交换参数也得到了调节。此外，细菌接种显著降低了脯氨酸、脂质过氧化、抗氧化酶以及Ag-NP在植物器官中的吸收和积累。总之，土壤接种BZ-13可能作为一种替代方法来保护生长在纳米颗粒污染土壤中的印度人参植物。因此，像BZ-13这样能够合成植物激素和其他生物分子且耐纳米颗粒的PGPR菌株，可能作为一种具有重要农学意义且成本效益高的修复剂，以提高在一般纳米颗粒污染土壤特别是Ag-NP污染土壤中种植的药用重要植物如印度人参的产量和生产力。
