植物miRNA启动子研究进展

Advances in the Research of miRNA Promoters in Plants

MicroRNA（miRNA）是广泛存在于植物基因组中的一类非编码小分子RNA,长度为20-24个核苷酸（nucleotides,nt）,作为一类重要的负调控因子,广泛参与植物的生长发育和逆境胁迫响应的调控。真核生物启动子是基因表达不可缺少的重要调控元件,包含转录起始位点（transcription start sites,TSS）、TATA框（TATA box）和上游的顺式作用元件。miRNA基因上游启动子与植物miRNA的组织、发育时期和胁迫诱导的表达特异性密切相关,而研究植物miRNA基因的启动子是揭示miRNA特异性表达的分子基础。因此,有必要系统阐述miRNA启动子的特点、核心元件和顺式作用元件的鉴定方法及植物中miRNA启动子研究的最新进展,进而分析植物miRNA启动子研究中存在的问题,为探讨miRNA介导的植物基因表达调控分子机制提供参考。

MicroRNAs（ miRNAs） are a class of 20 - 24 nucleotides（ nt） non-coding small RNAs with wide distribution in plant genomes. As one of the most important post-transcriptional regulators,miRNAs play a key role in gene expression and stress responses of plants through cleavage or translational repression by complete or partial complementarity to target mRNAs. MIRNA genes are generally known to be transcribed in the nucleus by RNA polymerase II（ Pol II） into a primary miRNA with two following continuous cleavages by Dicer-like 1 to produce a precursor miRNA and a miRNA： miRNA star duplex. Promoters are indispensable components involved in gene expression and contain transcription start sites（ TSS）,TATA boxes and upstream cis-acting elements. It is known that the promoters of miRNAs are important in regulating the expression of miRNA in specific plant tissues,development stages,biotic and abiotic stress responses of plants. As a consequence,investigations on promoters of MIRNA genes are fundamentally important to reveal the molecule mechanism of spatial and temporal expression of miRNAs and will be helpful to reveal the function of miRNAs involved in the biological processes of plants. Consequently,it is highly indispensable to review and analyze the characteristics of miRNA promoters,identification methods of miRNA core promoters and cis-acting elements. Furthermore,the advances of researches on miRNA promoters of plants such as Arabidopsis and rice,the possible problems and prospects of miRNA promoters investigations were also discussed to provide insights into the evaluation of miRNA-mediated gene regulation mechanism.