Alharby Hesham F, Ali Shafaqat
Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia.
Department of Environmental Science and Engineering, Government College University, Faisalabad 38000, Pakistan.
Life (Basel). 2022 Feb 24;12(3):338. doi: 10.3390/life12030338.
Chromium (Cr) is a toxic heavy metal whose high concentration in soil badly affects plant growth, photosynthesis, and overall yield. Metal-derived nano-particles and metal-resistant bacteria can strengthen the plant defense system against different abiotic stresses; however, little is known about the use of nanoparticles in conjunction with bacteria. This study examined the combined effect of Fe nanoparticles (Fe NPs) and a chromium-resistant bacterium on rice plants grown on chromium saturated medium. Chromium stress reduced rice growth, biomass, and chlorophyll contents by causing oxidative damage leading to overproduction of electrolyte leakage, hydrogen peroxide, and malondialdehyde. Fe NPs significantly improved plant growth, biomass, yield, and photosynthetic activity by enhancing the chlorophyll contents and alleviating oxidative damage. Application of Fe NPs also reduced the uptake and accumulation of Cr in the plants by increasing the bioavailability of micronutrients to the plant. The Fe NPs decreased oxidative damage and enhanced the enzymatic and non-enzymatic activity in the plant to withstand Cr stress compared to the plants without Fe NPs treatments. The inoculation of rice plants with the chromium-resistant bacteria further enhanced the positive impact of Fe NPs by transforming the toxic form of chromium (Cr) into a less toxic form of chromium (Cr). The bacterial inoculation reduced Cr uptake by plants through adsorption of Cr ions, resulting in decreased chromium ion bioavailability. At chromium level 100 mg/kg, the foliar application of Fe NPs from 0 to 20 mg/L increased the total chlorophyll contents from 2.8 to 3.9. The application of further enhanced the chlorophyll contents from 4.4 to 5.4, respectively. The current study suggested that combining Fe NPs and could be a viable strategy for reducing Cr toxicity and accumulation in rice plants and most likely other plants.
铬（Cr）是一种有毒重金属，其在土壤中的高浓度会严重影响植物生长、光合作用及总体产量。金属衍生的纳米颗粒和抗金属细菌可增强植物抵御不同非生物胁迫的防御系统；然而，关于纳米颗粒与细菌联合使用的情况却知之甚少。本研究考察了铁纳米颗粒（Fe NPs）和一种耐铬细菌对生长在铬饱和培养基上的水稻植株的综合影响。铬胁迫通过造成氧化损伤导致电解质渗漏、过氧化氢和丙二醛过量产生，从而降低了水稻的生长、生物量和叶绿素含量。Fe NPs通过提高叶绿素含量和减轻氧化损伤，显著改善了植物生长、生物量、产量及光合活性。Fe NPs的应用还通过提高植物对微量营养元素的生物有效性，减少了植物对铬的吸收和积累。与未进行Fe NPs处理的植物相比，Fe NPs减少了氧化损伤，增强了植物体内的酶促和非酶促活性以抵御铬胁迫。用耐铬细菌接种水稻植株，通过将有毒形式的铬（Cr）转化为毒性较小的铬（Cr）形式，进一步增强了Fe NPs的积极影响。细菌接种通过吸附铬离子减少了植物对铬的吸收，导致铬离子生物有效性降低。在铬含量为100 mg/kg时，叶面喷施0至20 mg/L的Fe NPs可使总叶绿素含量从2.8增加到3.9。[此处原文缺失细菌接种相关浓度数据]的应用分别进一步将叶绿素含量从4.4提高到5.4。当前研究表明，将Fe NPs和[此处原文缺失细菌名称]结合可能是降低水稻植株以及很可能其他植物中铬毒性和积累的可行策略。
