Sharma Deepika, Tiwari Manish, Lakhwani Deepika, Tripathi Rudra Deo, Trivedi Prabodh Kumar
CSIR-National Botanical Research Institute, Council of Scientific and Industrial Research (CSIR-NBRI), Rana Pratap Marg, Lucknow-226001, India.
Metallomics. 2015 Jan;7(1):174-87. doi: 10.1039/c4mt00264d. Epub 2014 Dec 4.
Arsenic (As) contamination of rice (Oryza sativa) imposes a serious threat to human health worldwide. Understanding the molecular mechanisms of As transport and accumulation in rice may provide promising solutions to the problem. MicroRNAs (miRNAs) are a novel class of short, endogenous, non-coding small RNA molecules involved in a wide variety of biological processes such as organ polarity, morphogenesis, floral transition, hormone signalling and adaptation to environment. In the past, a few studies led to the identification of differentially expressed miRNAs in rice in response to arsenite (As(III)) stress. However, studies related to differential miRNA expression involving natural rice accessions exposed to different species of As have not been carried out. Such studies are required to identify As-species responsive miRNAs in different rice accessions. In this study, we have carried out miRNA profiling in contrasting As accumulating rice accessions using miRNA Array. We report identification of differentially expressed miRNAs in contrasting As accumulating rice cultivars in response to As(III) (25 μM) and As(v) (50 μM) stress. A significant up-regulation in expression was observed among members of the miR396, miR399, miR408, miR528, miR1861, miR2102 and miR2907 families in response to As(III) and As(v) stress in both cultivars. In addition, members of the miR164, miR171, miR395, miR529, miR820, miR1432 and miR1846 families were down-regulated. The differentially expressed miRNAs were subjected to validation of expression and bioinformatic analyses to predict and categorise the key miRNAs and their target genes involved in As stress. Analysis suggests that As-species and rice accession specific miRNA might be responsible for the differential response of contrasting rice accessions towards As(III) and As(v) stress. Study of the proximal promoter sequences of the As-responsive miRNAs suggests that these identified miRNAs contain metal-responsive cis-acting motifs and other elicitor and hormonal related motifs. Our study suggests a miRNA-dependent regulatory mechanism during As species-specific stress in different rice accessions. Further analysis based on results obtained will be helpful in dissecting the molecular mechanism behind As responses in different rice accessions.
水稻（Oryza sativa）中的砷（As）污染对全球人类健康构成严重威胁。了解水稻中砷的运输和积累的分子机制可能为解决该问题提供有前景的方案。微小RNA（miRNA）是一类新型的短链、内源性、非编码小RNA分子，参与多种生物学过程，如器官极性、形态发生、花期转换、激素信号传导和环境适应。过去，一些研究鉴定出了水稻中响应亚砷酸盐（As(III)）胁迫而差异表达的miRNA。然而，尚未开展涉及暴露于不同种类砷的天然水稻种质的miRNA差异表达相关研究。此类研究对于鉴定不同水稻种质中对砷种类有响应的miRNA是必要的。在本研究中，我们使用miRNA芯片对砷积累特性相反的水稻种质进行了miRNA谱分析。我们报告了在砷积累特性相反的水稻品种中，响应As(III)（25 μM）和As(v)（50 μM）胁迫而差异表达的miRNA的鉴定结果。在两个品种中，miR396、miR399、miR408、miR528、miR1861、miR2102和miR2907家族成员在响应As(III)和As(v)胁迫时表达显著上调。此外，miR164、miR171、miR395、miR529、miR820、miR1432和miR1846家族成员表达下调。对差异表达的miRNA进行了表达验证和生物信息学分析以预测和分类参与砷胁迫的关键miRNA及其靶基因。分析表明，砷种类和水稻种质特异性miRNA可能是砷积累特性相反的水稻种质对As(III)和As(v)胁迫产生差异响应的原因。对砷响应miRNA近端启动子序列的研究表明，这些鉴定出的miRNA含有金属响应顺式作用基序以及其他诱导子和激素相关基序。我们的研究表明，在不同水稻种质中，砷种类特异性胁迫期间存在一种依赖miRNA的调控机制。基于所得结果的进一步分析将有助于剖析不同水稻种质中砷响应背后的分子机制。
