Current research has shown that microRNAs (miRNAs) play vital roles in plant response to stress caused by heavy metals such as aluminum, arsenic, cadmium (Cd), and mercury. Cd has become one of the most hazardous pollutants in the environment. Maize can be a potential model to study phytoremediation of Cd-contaminated soil owing to its large biomass production. However, little is known about miRNAs as a response to Cd stress in maize. To investigate the role of miRNAs in response to Cd stress, roots of seedlings of the inbred maize lines B73 and Mo17 were collected and treated with 200 mg/L CdCl2·2.5 H2O over different exposure times. Enzyme activities of superoxide dismutase and peroxidase were measured to confirm Cd stress. The expression of six candidate miRNAs and their targets were validated using quantitative real-time PCR (qRT-PCR) technology. In addition, the expression of Zma-miR171b was assessed using in situ hybridization. Our results showed that miRNAs and their respective target genes were differentially expressed in maize seedling roots exposed to Cd stress. This research produced new insights into the molecular mechanism of miRNAs responsive to Cd stress in plants and sheds light on the latent roles of miRNAs in plants exposed to heavy metal stresses.

中文翻译：

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玉米（Zea mays）根中镉响应性MicroRNA及其靶基因的表征。

当前的研究表明，microRNA（miRNA）在植物对铝，砷，镉（Cd）和汞等重金属引起的胁迫响应中起着至关重要的作用。镉已成为环境中最有害的污染物之一。玉米由于其大量的生物量生产而可能成为研究对Cd污染的土壤进行植物修复的潜在模型。然而，关于miRNA作为玉米中Cd胁迫反应的知之甚少。为了研究miRNA对Cd胁迫的响应，收集了玉米自交系B73和Mo17的幼苗根部，并在不同暴露时间下用200 mg / L CdCl2·2.5 H2O处理。测量了超氧化物歧化酶和过氧化物酶的酶活性以确认镉胁迫。使用定量实时PCR（qRT-PCR）技术验证了六个候选miRNA及其靶标的表达。另外，使用原位杂交评估Zma-miR171b的表达。我们的结果表明，miRNA及其各自的靶基因在暴露于Cd胁迫的玉米幼苗根中差异表达。这项研究产生了对植物中Cd胁迫响应的miRNA分子机制的新见解，并揭示了miRNA在暴露于重金属胁迫的植物中的潜在作用。