Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia.
Institute of Biotechnology and Genetic Engineering, The University of Agriculture, Peshawar, Pakistan.
Environ Pollut. 2022 Jan 15;293:118508. doi: 10.1016/j.envpol.2021.118508. Epub 2021 Nov 15.
Contamination of heavy metals is a serious threat, which causes threats to the environment. Our study aimed to determine the role of endophytic bacteria in Cd phytoremediation and heavy metal ATPase gene expression. Cadmium (Cd) resistant endophytic bacteria were isolated from Solanum nigrum on LB agar plates, contaminated with 0-30 mg/L Cd. The phosphate solubilization and indole-3-acetic acid (IAA) production of endophytes were estimated by growing them on Pikovskaya agar medium and GC-MS analysis, respectively. An experiment in a pot was performed to evaluate the effects of bacteria on rice plants contaminated with 5-25 mg/L of Cd. Expression of Cd response genes was quantified through qRT-PCR and Cd translocation from one part to another part of the plant was measured through the ICP. BLAST alignment of 16 S-rDNA gene sequences confirmed the bacterial isolates as Serratia sp. AI001 and Klebsiella sp. Strain AI002. Both strains tolerated Cd up to 25 mg/L and produced 27-30 μg/mL of IAA. Inoculation of AI001 and AI002 improved plant growth dynamics (i.e., plant length, biomass, chlorophyll contents), relieved electrolyte leakage, and improved reduced glutathione significantly (P < 0.05). The inoculation of AI001 and AI002 significantly (P < 0.05) induced the expression of heavy metal ATPase genes ie., "HMA2, HMA3, and HMA4" and Cd translocation compared to uninoculated plants. Both AI001 and AI002 exhibited very prominent plant-growth-promoting and Cd phytoremediation properties. The results revealed that isolates also contributed a lot to the expression of rice plant heavy metal ATPase genes and in the Cd translocation in the plant.
重金属污染是一个严重的威胁，对环境造成威胁。我们的研究旨在确定内生细菌在 Cd 植物修复和重金属 ATP 酶基因表达中的作用。从龙葵 LB 琼脂平板上分离出 Cd 抗性内生细菌，用 0-30mg/L 的 Cd 污染。通过在 Pikovskaya 琼脂培养基上生长和 GC-MS 分析分别估计了内生菌的溶磷和解吲哚乙酸（IAA）的产生。通过盆栽实验评估了细菌对受 5-25mg/L Cd 污染的水稻植株的影响。通过 qRT-PCR 定量了 Cd 响应基因的表达，并通过 ICP 测量了 Cd 从植物的一部分向另一部分的转移。16S-rDNA 基因序列的 BLAST 比对证实了细菌分离物为 Serratia sp. AI001 和 Klebsiella sp. Strain AI002。两种菌株均能耐受高达 25mg/L 的 Cd，并产生 27-30μg/mL 的 IAA。接种 AI001 和 AI002 可改善植物生长动态（即植物长度、生物量、叶绿素含量），减轻电解质泄漏，并显著提高还原型谷胱甘肽（P<0.05）。与未接种的植物相比，接种 AI001 和 AI002 显著（P<0.05）诱导了重金属 ATP 酶基因（即“HMA2、HMA3 和 HMA4”）和 Cd 转运的表达。AI001 和 AI002 均表现出非常突出的植物生长促进和 Cd 植物修复特性。结果表明，分离物还对水稻植物重金属 ATP 酶基因的表达和植物体内 Cd 的转运做出了很大贡献。
