Department of Agronomy and James D, Watson Institute of Genome Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China.
BMC Plant Biol. 2012 Feb 22;12:28. doi: 10.1186/1471-2229-12-28.
MicroRNAs (miRNAs) and short interfering RNAs (siRNAs) are two major classes of small RNAs. They play important regulatory roles in plants and animals by regulating transcription, stability and/or translation of target genes in a sequence-complementary dependent manner. Over 4,000 miRNAs and several classes of siRNAs have been identified in plants, but in tobacco only computational prediction has been performed and no tobacco-specific miRNA has been experimentally identified. Wounding is believed to induce defensive response in tobacco, but the mechanism responsible for this response is yet to be uncovered.
To get insight into the role of small RNAs in damage-induced responses, we sequenced and analysed small RNA populations in roots and leaves from wounding or topping treated tobacco plants. In addition to confirmation of expression of 27 known miRNA families, we identified 59 novel tobacco-specific miRNA members of 38 families and a large number of loci generating phased 21- or 24-nt small RNAs (including ta-siRNAs). A number of miRNAs and phased small RNAs were found to be responsive to wounding or topping treatment. Targets of small RNAs were further surveyed by degradome sequencing.
The expression changes of miRNAs and phased small RNAs responsive to wounding or topping and identification of defense related targets for these small RNAs suggest that the inducible defense response in tobacco might be controlled by pathways involving small RNAs.
微小 RNA（miRNAs）和短干扰 RNA（siRNAs）是两类主要的小分子 RNA。它们通过序列互补依赖性调节靶基因的转录、稳定性和/或翻译，在动植物中发挥重要的调节作用。在植物中已经鉴定出超过 4000 种 miRNAs 和几类 siRNAs，但在烟草中仅进行了计算预测，尚未实验鉴定出烟草特异性 miRNAs。创伤被认为会诱导烟草的防御反应，但负责这种反应的机制尚未被揭示。
为了深入了解小分子 RNA 在损伤诱导反应中的作用，我们对来自创伤或打顶处理的烟草植物的根和叶中的小 RNA 群体进行了测序和分析。除了确认 27 个已知 miRNA 家族的表达外，我们还鉴定了 38 个家族的 59 个新的烟草特异性 miRNA 成员和大量产生相位 21 或 24 个核苷酸的小 RNA（包括 ta-siRNAs）的基因座。许多 miRNA 和相位小 RNA 被发现对创伤或打顶处理有反应。通过降解组测序进一步调查了小 RNA 的靶标。
对创伤或打顶处理有反应的 miRNAs 和相位小 RNA 的表达变化以及这些小 RNA 的防御相关靶标的鉴定表明，烟草中的诱导防御反应可能受涉及小 RNA 的途径控制。
