College of Horticulture, Nanjing Agricultural University, Nanjing, China.
Plant Biol (Stuttg). 2010 Nov;12(6):927-34. doi: 10.1111/j.1438-8677.2009.00300.x.
MicroRNAs (miRNAs) are a new family of small RNA molecules found in plants and animals. We developed a comprehensive strategy for identifying new miRNA homologues by mining the repository of available citrus expressed sequence tags (ESTs). By adopting a range of filtering criteria, we identified a total of 38 potential miRNAs--nine, five, nine and 15 miRNAs in Citrus trifoliata (ctr-miRNAs), C. clementina (ccl-miRNAs), C. reticulata (crt-miRNAs) and C. sinensis (csi-miRNAs), respectively--from more than 430,000 EST sequences in citrus. Using the potential miRNA sequences, we conducted a further BLAST search of the mRNA database and found six potential target genes in these citrus species. Eight miRNAs were selected in order to verify their existence in citrus using Northern blotting, and the functions of several miRNAs in miRNA-mediated gene regulation are experimentally suggested. It appears that all these miRNAs regulate expression of their target genes by cleavage, which is the most common situation in gene regulation mediated by plant miRNAs. Our achievement in identifying new miRNAs in citrus provides a powerful incentive for further studies on the important roles of these miRNAs.
MicroRNAs (miRNAs) 是在动植物中发现的一种新的小 RNA 分子家族。我们通过挖掘现有的柑橘表达序列标签 (EST) 库，开发了一种全面的识别新 miRNA 同源物的策略。通过采用一系列过滤标准，我们在柑橘中鉴定了总共 38 个潜在的 miRNA——在枳（ctr-miRNAs）、克莱门氏小柑橘（ccl-miRNAs）、红江橙（crt-miRNAs）和甜橙（csi-miRNAs）中分别有 9、5、9 和 15 个 miRNA——来自超过 430000 个柑橘 EST 序列。使用潜在的 miRNA 序列，我们对 mRNA 数据库进行了进一步的 BLAST 搜索，在这些柑橘物种中发现了 6 个潜在的靶基因。选择了 8 个 miRNA 进行 Northern 印迹实验，以验证它们在柑橘中的存在，并且实验提出了几个 miRNA 在 miRNA 介导的基因调控中的功能。似乎所有这些 miRNA 都通过切割来调节其靶基因的表达，这是植物 miRNA 介导的基因调控中最常见的情况。我们在柑橘中鉴定新 miRNA 的成果为进一步研究这些 miRNA 的重要作用提供了有力的动力。
